This very simple circuit uses a transformer ,two diodes , a capacitor and an ammeter.
To charge a battery just connect the + and - terminals of the circuit to the corresponding terminals of the battery.
When the battery is not charged, the ammeter reading shows 1-3 amps.
When the battery is fully charged the ammeter reads Zero or nearly zero, after which the battery should be removed from the
charger.
The circuit is a full wave rectifier using 2 diodes for rectification. The capacitor is used for smoothing.
I think the circuit works fine without the capacitor since the battery itself acts a BIG capacitor. But when you are using the
circuit to supply 12V (as a battery eliminator) the capacitor needs to be present.
Care should be taken NOT to reverse the + and - terminals while connecting it to the battery.
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Voltage variations and power cuts adversely affect various equip- ment such as TVs, VCRs, music systems and refrigerators. This simple circuit will protect the costly equipment from high as well as low voltages and the voltage surges (when power resumes). It also gives a melodious tune when mains power resumes. When mains voltage is normal, the DC voltage at the cathode of zener diode D4 is less then 5.6V. As a result transistor T1 is in �off� state. The DC voltage at the cathode of zener diode D5 is greater than 5.6V and as a result transistor T2 is in �on� state. Consequently, relay RL1 gets energised, which is indicated by lighting up of green LED. Under high mains voltage condition, transistor T1 switches to �on� state because the voltage at cathode of zener diode D4 becomes greater than 5.6V. Consequently, transistor T2 switches to �off� state, making the relay to de-energise Under low mains voltage condition, transistor T1 switches to �off� state and as a result transistor T2 also switches to �off� state, making the relay to de-energise.
Timer IC 555 in the circuit is configured to operate in a monostable mode. The pulse width is about 10 seconds with the timing component values used in the circuit. When the power resumes after a break, pin 2 of IC 555 goes low briefly and this triggers it. Its output makes music IC UM66 to operate through transistor T3. Simultaneously, transistor T1 also gets forward biased as the monostable IC1 output is connected to its base via diode D8 and resistor R7. As a result, transistor T1 conducts and biases transistor T2 to cut off. Thus relay RL1 remains de-energised for the duration of mono pulse and the load is protected against the voltage surges.
To adjust presets VR1 and VR2, you may use a manually variable auto-transformer. Set the output of auto-transformer to 270V AC and connect it to the primary of transformer X1. Adjust preset VR1 such that relay RL1 just de-energises. Next set the output of auto-transformer to 170V AC. Now adjust preset VR2 such that relay RL1 again de-energises. Volume control VR3 may be adjusted for the desired output volume of the tune generated by IC UM66
This over/under voltage cut-out will save your costly electrical and electronic appliances from the adverse effects of very high and very low mains voltages. The circuit features auto reset and utilises easily available components. It makes use of the comparators available inside 555 timer ICs. Supply is tapped from different points of the power supply circuit for relay and control circuit operation to achieve reliability. The circuit utilises comparator 2 for control while comparator 1 output (connected to reset pin R) is kept low by shorting pins 5 and 6 of 555 IC. The positive input pin of comparator 2 is at 1/3rd of Vcc voltage . Thus as long as negative input pin 2 is less positive than 1/3 Vcc, comparator 2 output is high and the internal flip-flop is set, i.e. its Q output (pin 3) is high. At the same time pin 7 is in high impedance state and LED connected to pin 7 is therefore off. The output (at pin 3) reverses (goes low) when pin 2 is taken more positive than 1/3 Vcc. At the same time pin 7 goes low (as Q ouptput* of internal flip- flop is high) and the LED connected to pin 7 is lit. Both timers (IC1 and IC2) are configured to function in the same fashion. Preset VR1 is adjusted for under voltage (say 160 volts) cut-out by observing that LED1 just lights up when mains voltage is slightly greater than 160V AC. At this setting the output at pin 3 of IC1 is low and transistor T1 is in cut-off state. As a result RESET* pin 4 of IC2 is held high since it is connected to Vcc via 100 kilo-ohm resistor R4. Preset VR2 is adjusted for over voltage (say 270V AC) cut-out by observing that LED2 just extinguishes when the mains voltage is slightly less than 270V AC. With RESET* pin 4 of IC2 high, the output pin 3 is also high. As a result transistor T2 conducts and energises relay RL1, connecting load to power supply via its N/O contacts. This is the situation as long as mains voltage is greater than 160V AC but less than 270V AC. When mains voltage goes beyond 270V AC, it causes output pin 3 of IC2 to go low and cut-off transistor T2 and de-energise relay RL1, in spite of RESET* pin 4 still being high. When mains voltage goes below 160V AC, IC1�s pin 3 goes high and LED1 is extinguished. The high output at pin 3 results in conduction of transistor T1. As a result collector of transistor T1 as also RESET* pin 4 of IC2 are pulled low. Thus output of IC2 goes low and transistor T2 does not conduct. As a result relay RL1 is de-energised, which causes load to be disconnected from the supply. When mains voltage again goes beyond 160V AC (but less than 270V AC) the relay again energises to connect the load to power supply
The circuit is a MOSFET based linear voltage regulator with a voltage drop of as low as 60 mV at 1 ampere. Drop of a fewer millivolts is possible with better MOSFETs having lower RDS(on) resistance. The circuit in Fig. 1 uses 15V-0-15V secondary from a step-down transformer and employs an n-channel MOSFET IRF 540 to get the regulated 12V output from DC input, which could be as low as 12.06V. The gate drive voltage required for the MOSFET is generated using a voltage doubler circuit consisting of diodes D1 and D2 and capacitors C1 and C4. To turn the MOSFET fully on, the gate terminal should be around 10V above the source terminal which is connected to the output here. The voltage doubler feeds this voltage to the gate through resistor R1. Adjustable shunt regulator TL431 (IC2) is used here as an error amplifier, and it dynamically adjusts the gate voltage to maintain the regulation at the output. With adequate heatsink for the MOSFET, the circuit can provide up to 3A output at slightly elevated minimum voltage drop. Trimpot VR1 in the circuit is used for fine adjustment of the output voltage. Combination of capacitor C5 and resistor R2 provides error-amplifier compensation. The circuit is provided with a short-circuit crow-bar protection to guard the components against over-stress during accidental short at the output. This crow-bar protection will work as follows: Under normal working conditions, the voltage across capacitor C3 will be 6.3V and diode D5 will be in the off state since it will be reverse-biased with the output voltage of 12V. However, during output short-circuit condition, the output will momentarily drop, causing D5 to conduct and the opto-triac MOC3011 (IC1) will get triggered, pulling down the gate voltage to ground, and thus limiting the output current. The circuit will remain latched in this state, and input voltage has to be switched off to reset the circuit. The circuit shown in Fig. 2 follows a similar scheme. It can be utilised when the regulator has to work from a DC rail in place of 15V-0-15V AC supply. The gate voltage here is generated using an LM555 charge pump circuit as follows: When 555 output is low, capacitor C2 will get charged through diode D1 to the input voltage. In the next half cycle, when the 555 output goes high, capacitor C3 will get charged to almost double the input voltage. The rest of the circuit works in a similar fashion as the circuit of Fig. 1. These circuits above will help reduce power-loss by allowing to keep lower input voltage range to the regulator during initial design or even in existing circuits. This will keep the output regulated with relatively low input voltage compared to the conventional regulators. The minimum voltage drop can be further reduced using low RDS(on) MOSFETs or by paralleling them
One of the main features of the regulated power supply circuit being presented is that though fixed-voltage regulator LM7805 is used in the circuit, its output voltage is variable. This is achieved by connecting a potentiometer between common terminal of regulator IC and ground. For every 100-ohm increment in the in-circuit value of the resistance of potentiometer VR1, the output voltage increases by 1 volt. Thus, the output varies from 3.7V to 8.7V (taking into account 1.3-volt drop across diodes D1 and D2).
Another important feature of the supply is that it switches itself off when no load is connected across its output terminals. This is achieved with the help of transistors T1 and T2, diodes D1 and D2, and capacitor C2. When a load is connected at the output, potential drop across diodes D1 and D2 (approximately 1.3V) is sufficient for transistors T2 and T1 to conduct. As a result, the relay gets energised and remains in that state as long as the load remains connected. At the same time, capacitor C2 gets charged to around 7-8 volt potential through transistor T2. But when the load is disconnected, transistor T2 is cut off. However, capacitor C2 is still charged and it starts discharging through base of transistor T1. After some time (which is basically determined by value of C2), relay RL1 is de-energised, which switches off the mains input to primary of transformer X1. To resume the power again, switch S1 should be pressed momentarily. Higher the value of capacitor C2, more will be the delay in switching off the power supply on disconnection of the load, and vice versa.
Though in the prototype a transformer with a secondary voltage of 12V-0V, 250mA was used, it can nevertheless be changed as per user�s requirement (up to 30V maximum. and 1-ampere current rating). For drawing more than 300mA current, the regulator IC must be fitted with a small heat sink over a mica insulator. When the transformer�s secondary voltage increases beyond 12 volts (RMS), potentiometer VR1 must be redimensioned. Also, the relay voltage rating should be redetermined.
This circuit solves the problem to a certain extent. It provides a negative voltage from a single positive supply. This negative voltage together with the positive supply can be used to power the opamps and other circuits requiring a dual supply.
The circuits operation can be explained as follows:
The 555 IC is operating as an astable multivibrator with a frequency of about 1kHz. A square wave is obtained at the pin 3 of the IC . When the output is positive, the 22uF capacitor charges through the diode D1. When the output at pin 3 is ground, the 22uF discharges through the diode D2 and charges the 100uF capacitor is charged. The output is taken across the 100uF capacitor as shown in the figure.
Also the output negative voltage will be a little less than the positive supply due to the diode drops. For example if the voltage is +9V then the output voltage will be about 7.5 V.
This drink is so simple and used to be as common as milk - well as far as morning drinks go anyway. You most likely have heard of it and perhaps you remember some distant Aunt telling you about it, praising the benefits as you wiped it off as an old wives tale.
It doesn't have a name, I just call it the ACV and honey drink and it consists of apple cider vinegar and honey and hot water. Drink it every morning whether you are cleansing or not. It is the best way to start the day. Simply mix it into boiled water - the exact recipe is further down this article. But before I show you how to make it let me run you through the why, as once you know the why you will be self motivated to drink it as you will understand and want the benefits.
Let's talk about honey. Honey is sweet, yummy, good looking and is one of God's nectars, and is absolutely PACKED FULL of antioxidants. There has been a lot of talk about antioxidants; we have been told by the medical experts that they are good for us but sometimes we forget why, because when we read about them it can seem so complicated that it is difficult to comprehend and easy to forget. So I am going to tell you about antioxidants in a way that I understand them and I hope this will help you understand them too. Remember knowledge is power and you can utilize this power to benefit yourself.
Let's start with a simple ABC
A - Cells consist of molecules.
B - Molecules consist of atoms.
C - Atoms consist of a nucleus, neutrons, protons, and electrons.
OK, so far so good. Now, electrons are required to keep the atom stable. If the atom doesn't have enough of their own electrons, they will actually share electrons with other atoms. To share the electrons, atoms don't split electrons in half, but instead bond themselves together, enabling them to literally share electrons to ensure they maintain stability.
If this bond is weak and splits it becomes a Free Radical which is a loose or unbalanced atom or molecule.
Free radicals will attack the nearest unstable atom to steal it's electron, thereby turning that atom into a free radical as well, and so on it goes, and eventually this vicious cycle will destroy the entire living cell!
Not all free radicals are bad, though. Free radicals are sometimes created by our body's immune system to fight bacteria and viruses. But sometimes they are spawned from pollution, radiation, cigarette smoke, and herbicides.
Antioxidants can stop the free radicals from stealing electrons from other atoms, as they are able to donate to the atoms one of their own electrons. Generally antioxidant-containing foods are sweet, such as berries and honey.
So now I hope you understand a little better that we need to always have antioxidants available within our systems to supply electrons to atoms (when they are needed to stabilise atoms) and in turn keeping your cells alive.
An example of an essential time to have available antioxidants is after you've had a virus such as the flu. Your body would have been producing free radicals to fight the virus (bad cells) so you now would require antioxidants to repair the good cells.
Regularly consuming honey, such as when drinking apple cider and vinegar every morning, will maintain healthy levels of antioxidants in your blood.
The combination of the apple cider, honey, and warm water cleanses your blood. The cleansing and antibiotic properties are equal to eating an entire bowl of fruit, and the warm water helps to carry it through your system to purify your blood, reduce fat, and clean your bowels. It really is a fabulous all-in-one. If you can't drink the apple cider vinegar, swap it for lemon juice. Or better yet, take ACV tablets instead. If your health food shop doesn't stock them yet, ask them to.
Here is the recipe: 1 soup spoon Apple Cider Vinegar 1 soup spoon Honey Top up cup or mug with hot water Green Tea is also one of the best ways to get your supply of antioxidants. Green Tea has so impressed health professionals around the world with its effective antioxidants that neutralise free radicals that you will soon hear about the effectiveness of green tea against cancer. And not only is that impressive but White Tea is showing itself to be even more effective than green tea although caffeine levels are higher but thankfully both are available in caffeine free varieties. When choosing caffeine free products select the one that states it is 'naturally decaffeinated' so you know there are no residue chemicals left behind.
Everyone I meet that drinks green tea seems to be very healthy and always mention that they drink the tea. I have a friend who has drank green tea most of her life, morning and night and she has never ever had cellulite - and she never will.
So there you have it, a simple yet effective cellulite banishing drink to set you up for a healthy cellulite free life that you can start your day with every day.
Bronwyn Hewitt
Cellulite Therapist
Email: ask@celluliteinfo.info
Website: http://www.celluliteinfo.info
Treatments: http://www.cellulitefreeme.com
Cellulite Therapist, operating since 1990. Bronwyn is also the creator of The Ultimate Cellulite Treatment. Bronwyn introduced C-Zone Therapy in 2008 and is author of The Ultimate Cellulite Treatment in a Book that has sold all over the world since being launched in 2005. She continues to teach ladies how to find the cause of their cellulite and how to get rid of the cellulite they already have for ever, using C-Zone Therapy. Bronwyn is based on the Mornington Peninsula in Victoria Australia.
VMT Technologies says its new "Universal Transmission" saves 30-percent in fuel costs over standard transmission and will also outperform CVT transmissions as well. According to the company, "the Universal Transmission is the first and only to function as a positively engaged, infinitely variable transmission with an engaged neutral. In addition, it eliminates the need for a clutch or torque converter."
Now, since electric cars and hydrogen fuel cell vehicle, thought to be the future of the automotive industry run on electric motors and not transmissions, VMT Technologies intends on competing in these sectors as well.
There are two technologies surrounding hydrogen. One is called a "hydrogen converter" which uses DC voltage to split water into hydrogen and oxygen. These gases are used as the fuel in internal combustion engines and many other energy applications.
The other hydrogen technology is called the; "hydrogen fuel cell". This uses hydrogen gas to produce electrons. Batteries also produce electrons. The use of electrons is described basically in two ways. The force pushing the electron "Volts" and how many electrons are passing a particular point "amps". If we compared electricity to water the volts would be pressure and the amps would be flow.
Like hydrogen cells, batteries produce electrons to use instead of gasoline or diesel. Electrons from "plug-in electricity" must be stored and then drawn as acceleration is required. Just like water in a tank there are only so many electrons available to take with you. That's why the number of electrons (amps) you use is so important. It's all a trade off.
One battery will provide enough voltage and amps to move a midsize car, just not very far. The further you want to go the more electron storage (batteries) you need to take with you. A good analogy would be; a battery is equal to a gallon of gas. The tradeoffs are; Cost (for the batteries or hydrogen tanks), Weight and range. Everyone wants low cost and weight and long range.
"An object at rest tends to stay at rest" and "an object in motion tends to stay in motion". The fact is, it takes more energy to get something moving than it does to keep it moving. Similarly, it takes more electrons (amps) for an electric motor to accelerate a car than it does to keep it going. Amps (number of electrons) melt things, explode things and kill people. To control this, a "controller" is needed.
The controller in the hybrid or the electric car has to manage the amps when a lot of them are needed. Therefore it has to be very robust to keep from melting and that becomes expensive.
VMT is advocating that it would be better to conserve the precious electron energy by using the mechanical advantage of VMT's IVT, especially when the transmission costs less than the controller. Another benefit comes from not needing as many amps; you don't need as many volts. A lower voltage battery is safer and less expensive.
So, the question comes: do you need both a controller and a transmission - no. As noted battery expert John Wyall notes, "As far as the difference between using a controller and using and IVT is concerned, the IVT is cheaper and safer than the controller. The IVT allows you to use fewer cells, thus making the battery a manageable system, and with lower voltage, a safer system. The controller-electric motor and gear box system has about the same overall efficiency as a controller-less electric drive with an IVT."
Copyright © 2009 Kevin Kamptroller, all rights reserved.
Elementary science teaches us that everything in the world is made up of tiny particles called atoms. An atom is made up of a hard core, called a nucleus, and a cloud of fast whizzing particles called electrons that move around the nucleus. Sometimes electrons can even jump from one place to another. When electrons move, this creates a current of electricity.
When you see lightning up in the sky, you're actually seeing billions of electrons jumping all at once from one place to another. Moving electrons tend to release a lot of energy, and we can use this electricity to do all kinds of things, from powering a computer to splitting an atom apart.
Our bodies also use electricity. Every thought that you have is the result of tiny electrical signals jumping between the cells in your brain. Everything that you feel is an electrical message passed down long pathways called nerves that run from your body to your brain. Even your heart is controlled by electrical signals that tell each cell in your heart when to beat.
A heart attack happens when this electrical signal gets mixed up and every cell in your heart tries to beat at a different time. That's why doctors can use a machine called a defibrillator to deliver a powerful electric shock to your heart - it resets all the heart cells and gets them beating in time again!
Here's a fun and easy elementary science experiment you can do to see electricity at home:
A Hair-Raising Experiment
1. Blow up a balloon and tie a knot in the end to keep the air from escaping.
2. Rub the balloon quickly back and forth over your head for ten seconds.
3. Slowly pull the balloon away. Watch what happens to your hair.
4. Touch the balloon to a smooth surface, like a wall, and let go. If you rubbed enough, it should stick!
What's Happening:
Have you ever heard the saying "opposites attract"? Well, that's true of electric charges, too. Electrons have a negative charge, and the protons that make up the nucleus of an atom have a positive charge. Electrons push away from other electrons, but are strongly attracted to things with a positive charge. There are usually the same number of protons and electrons in an atom, so most of the time, they cancel each other out.
When you rub the balloon over your hair, the balloon grabs electrons from the atoms in your hair. Now there are more electrons than protons in the balloon, and fewer electrons than protons in your hair. This leaves the balloon with a negative charge and your hair with a positive charge. Since opposites attract, the negatively charged balloon sticks to your positively charged hair!
When you touch the balloon to the wall, the electrons in the atoms of the wall are repelled by the balloon and move away from it, but the protons in the wall are attracted to the electrons in the balloon and move slightly toward it. The negative charge in the balloon is attracted to the positive charge in the wall, and zap! It sticks just like a magnet.
Now that is shocking science!
Discover more kids science articles, look up amazing fun facts, do animated science quizzes with talking characters, meet friends in virtual worlds, play games and do fun science activities at Science Score - the world's most fun online elearning product for kids. Join the thousands of kids to play with Science Score and do well in Science.
Sarah Jane Elliott is a contributing author of curious science articles for an online kids science portal (http://www.sciencescore.com). She holds a honors bachelor of Science degree from University of Toronto, specializing in zoology and behavior. Sarah is an author of speculative fiction, as well as a teacher and museum educator.
So what are LEDs? LED stands for light emitting diodes. They are essentially tiny light bulbs that fit snugly into an electrical circuit. However, they differ from incandescent bulbs because they don't have filaments that burn out. And as a result, they don't get that hot either. The way they illuminate is by way of movement of electrons in a semiconductor material. A semiconductor is a solid state substance that can be changed through electricity. A conductor is the mid point between conductors and insulators. In layman's terms, a semiconductor has differing abilities to conduct electric currents. LEDs are also capable of lasting as long as a standard transistor.
Semiconductors with extra electrons are referred to as N-type material, due to their extra negative charge. Free electrons move from a negatively charged area to a positively charged one. P-type material are semiconductors with extra holes. This enables electrons to jump from hole to hole. Why is this information important? Diodes are comprised of a section of N-type material bonded to a section of P-type material. The electrodes are placed on both ends. This configuration forces electricity conduction in one direction. When there is no voltage applied, electrons from the N-type material fill holes from the P-type material, which forms a depletion zone.
In this state, the semiconductor is at its original insulating state, and there are no free electrons or empty space for electrons, so there is no charge flow. In order for there to be flow, electrons must move from N-type to P-type, and the holes must move in the opposite direction. You do this by connecting the N side to a negative circuit and the P side to the positive. The voltage difference enables electrons in the depletion zone to begin to move freely. This interaction between electrons and holes creates light.
Find red led flashlight at http://www.red-ledflashlight.com
Electrons are involved in chemical reactions and are what bonds atoms together to form molecules. The number of electrons that form part of a molecule is important since it is what decides to a large extent the chemical behavior of that molecule. Basically, matter that has particles consisting of paired electrons will not react chemically. Because the nature of atoms is to find a state of maximum stability, particles and atoms that have un-paired electrons in their surrounding shell will attempt to 'steal' other electrons to pair them up with, either gaining them from other particles or by bonding with other particles to share electrons - this is a chemical reaction.
Electrons are positively charged and when they move between molecules so the charge of those particles becomes changed as well. This process of a particle losing some charge is termed 'oxidation' and theoretical change in the charge of a particle is referred to as the change in its oxidation state. When the process of oxidation in the human body, or in any other organic matter, causes tissue damage then this is often referred to as oxidative stress.
Free Radicals
The term 'free radical' is a chemical term and describes a particle or atom that has one or more unpaired electrons in its outer shells. These are unstable because of their need, chemically, to seek electrons from other atoms or ions. If a free radical particle can take an electron from another particle then that particle is left with un-paired electrons and so it becomes a free radical and so on in a chain reaction in many situations. These chemical reactions play an important role in atmospheric chemistry many other chemical processes, including human physiology.
Free radicals play an important role in the human biology such as the intracellular destruction of harmful bacteria and viruses. However, stress and environmental factors such as pollution, radiation, and cigarette smoke is known to generate free radicals. Since free radicals are necessary for life, the body has a number of mechanisms to minimize free radical damage and to repair damage which does occur. However because of their reactivity, free radicals can cause unwanted reactions as well which can result in tissue damage. Free radical damage is also cumulative so the effects increase with age.
Antioxidants are substances that can remain in a stable form even when they lose an electron from a pair - vitamins E and C are examples of antioxidants that occur naturally. The body naturally maintains a system of multiple types of antioxidants, such as vitamins C and E to help counteract harmful processes such as oxidation. Maintaining healthy levels of antioxidants by eating a well-balanced diet can help ensure your body is best able to deal with the harmful effects of free radicals.
Find out more about what are free radicals at the amida skin care products article center.
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The chemistry of fireworks colors
Let's start with the basic structure of the atom. Every atom has a nucleus that contains protons which are positively charged with negatively charged electrons in orbitals around the nucleus. The number of protons is equal to the number of electrons so that the atom overall is neutral. Now electrons will be in the lowest energy orbital that is possible to be stable. This will be the orbital closest to the nucleus. Let's take lithium as an example. Lithium is the third element in the periodic table and has three protons and three electrons. Two electrons are in an orbital close to the nucleus. This orbital can only hold two electrons as it is has a small radius. So the third electron goes in an orbital a bit farther away from the nucleus. We say that lithium has an electronic configuration of 2,1. An electronic configuration is just a way of saying where the electrons are!
Now there are lots more orbitals further away from the nucleus that are empty in the case of lithium. They are higher in energy as they are further from the pull of the nucleus so an electron would need more energy to stay in those orbitals. If we give that one lone electron some energy, for instance in the form of heat, then it can jump from it's orbital into a higher orbital. Once there it is unstable and falls back to its original starting point. However, when it falls back it has to lose that extra energy and it does this in the form of light. The light is emitted and the wavelength of the light depends on the difference between the energies of the starting and finishing orbitals. These will be different for different metals so the wavelength of the light will be different. For lithium the main transition that occurs emits light that is red. Other metals emit light as shown below.
Sodium -------- yellow/orange
Potassium -------- lilac
Calcium -------- brick red
Barium -------- light green
Copper -------- blues
So we can use metals in fireworks that, when they absorb energy from the burning charcoal, emit light of different colors. Other metals that can be added are magnesium which emits a brilliant white light, and aluminum and titanium which also produce white light and increase the temperature at which the firework burns.
So now, when you see a fireworks display you will know how those colors are produced. Knowing the science behind everyday events doesn't spoil the enjoyment but increases it. How much more fascinating to know exactly what is happening and still be able to be in awe at the wonderful events that happen around us everyday.
For more information on chemistry in everyday life visit Chemistry of Fireworks or Chemistry in Everyday Life.
But how do these panels actually absorb energy and transfer into energy that you can use in your home?
PV panels are made up of treated silicon and other materials including an antireflective coating. The silicon is a semi-conductor (like metal, not like plastic). When the light hits the silicone semi-conductor, a portion of the energy is absorbed by the panel and knocks electrons in the silicon loose which allows them to flow freely. The PV panels have an electric field that forces these 'freed' electrons to flow in a specific direction - and we all know that electrons flowing in a specific direction is known as 'current'.
In detail - how does it work?
Silicone atoms have 14 electrons in 3 different shells. Two of the shells are 'full' and the third shell is 'half empty'. So, this third shell is always looking for ways to fill itself up with 4 more electrons and so each silicon atom shares electrons with 4 of it's neighbours - sharing one electron with each neighbour.
But silicone itself isn't quite good enough - without impurities being added to the silicon structure, the electrons remain static so they don't flow 'freely'. So impurities like phosphorous or boron are added into the mix in small quantities. This means that the balance of electrons is adjusted enough to let 'freed' electrons play musical chairs looking for shells to drop into.
In a solar panel, phosphorous is added to make 'negative' cells and boron is added to make 'positive' cells, and when electrons are freed the current will flow from the negative to the positive side - current.
Once current is created (direct current - DC) it needs to be converted into alternating current (AC) so that it can be used in normal household appliances. That's where the inverter steps in.
Liz Brock is the resident blogger for http://www.servicecentral.com.au - Australia's first online services marketplace. We write articles relevant to the trades and home services industry for both trades businesses and consumers looking to find quality tradespeople locally.
To read the original article and join in the discussion, go to our website here http://www.servicecentral.com.au/resources/articles/How-do-photovoltaic-panels-solar-panels-work/832
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Periodic Table is a row and columns of elements put in sequence of various trends. They are very harmoniously synchronised that you can easily predict a lot about the element just by looking at the position it is placed on the Periodic Table.
Elements are naturally occurring chemicals and they contain atoms of only one kind. Periodic Table contains all the elements that have been discovered so far and are still being added on as more elements come to discovery. Each element has a symbol, atomic number and atomic mass. Symbol is displayed in the middle. On the top of the symbol, an atomic number is displayed and on the bottom it is the atomic mass. Atomic number shows how many protons and electron make up one atom of this element and the Atomic mass show the mass of the nucleus of this element. The nucleus of an atom of element is made up of protons and neutrons. Elements are arranged in groups which are the columns. There are 8 groups of elements and group number tells us how reactive each element is. For example in group one the element are very reactive but in group 8 all elements are very unreactive. It is because, elements of group one contain only one electron in the outer shell as they are meant to have 8 electron. As they are 7 electrons short, they are considered to be highly reactive. Whereas in group 8, the elements contain 8 electrons in the outer shell and as they are meant to have 8, they are very much stable and therefore considered very unreactive. Group 4 elements can be reactive and unreactive equally.
There are rows of elements which tell us how many shells there are around the atoms of each element. These rows are called periods. In period one, all the elements have one shell around their atoms. For any atom to be stable it must have its shells complete of electron. Any atom with incomplete shells is likely to be reactive. The number of electron for stability is 8. If an atom has two electrons, it either must gain 6 more electrons or lose its two electrons in order to become stable. Losing two electrons are easier than gaining 6 so atom opts to lose two electrons. The number of shells determines how easily those outer electrons are lost or gained. For atoms that are looking to lose electron, having more shells means, the electrons can easily be lost as the nucleus is shielded with shells hence the element is more reactive. But for atoms that are looking to gain electron, more shells means it's difficult to gain outer electrons therefore the element becomes less reactive.
With more shells, the atom also becomes bigger; we say that the atomic radius increases with number of shells. Across the Periodic Table, the Atomic Radii decreases and down the group the Atomic Radii increases. Group 1 and 2 are classed as Metals and are also called group-S elements. Group 3 - 8 are all non-metals and are also classed as group -p elements. The elements in between these groups are called the transition metals or group -d elements.
Anyone struggling with the fundamentals of Chemistry can contact Dr Chand Zahid for an on-line tuition.
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When we see a piece of iron rusting, or a slice of apple turning brown, we are looking at examples of relatively slow oxidation. When we look at a fire, we are witnessing an example of rapid oxidation. We now know that oxidation involves an exchange of electrons between two atoms. The atom that loses an electron in the process is said to be "oxidized." The one that gains an electron is said to be "reduced." In picking up that extra electron, it loses the electrical energy that makes it "hungry" for more electrons. Thus we get the term Oxidation (losing an electron) Reduction (gaining and electron) Potential.
The potential of a given substance to take or leave electrons is very important. If you consistently drink water with a high positive ORP or Oxidation Reduction Potential, the water will have a tendency to steal electrons from the other atoms in your body, oxidizing your other atoms. Remember the examples above of iron rusting and an apple turning brown. Basically that is what water with a high ORP will do to you. Examples of drinks with a high positive ORP are coffee, soda, bottled water, Gatorade and Powerade, and almost every drink sold at stores. Even tap water has a high ORP even though it is required by law to have a neutral pH level.
If you consistently drink water with a high negative ORP or Oxidation Reduction Potential, the water will have a tendency to leave electrons with atoms in your body that are need of them. The water will basically reduce the atoms that are missing electrons so that those atoms and molecules do not oxidize your body. Again, remember that oxidation causes decay. You do not want that. The only water that I am aware of that has a high negative ORP is alkaline water, usually produced by a special water ionizer. Alkaline Water can virtually reverse the negative effects of all of the oxidizing drinks and foods that we eat daily.
You may have also heard of the term anti-oxidant. Simply stated an anti-oxidant is a substance that as a high negative ORP or Oxidation Reduction Potential. There is a huge market for anti-oxidants because they help prevent your body from decaying and oxidizing. The best anti-oxidant available is alkaline water.
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Let us imagine a collection of smaller particles that are joined together in such a way so that a fixed number of them comprise a single electron. I will call these particles "Om Particles" named after the word "Om" in Hindu meaning the elementary vibration of all existence. These Om particles are connected together and arranged much like a set of baby's plastic linking beads that can be snapped together end to end. Taking this a step further, let us take enough of these particles and put them together in a string so that they can be curved around to form a closed loop. It is this loop formation of Om particles that creates our electron. I cannot be certain exactly how many Om particles it takes to form a single electron but I will surmise that careful studies of the relative fractional values of the masses of known sub-atomic particles when compared to the mass of a single electron will lead a common denominator which should tell us the value of the mass of a single Om particle and, as a result, yield the number required to form a single electron. The reason for this is that I believe that every particle in the universe is made up of these Om particles and therefore should have masses that are some multiple of the Om particle's mass.
One other piece of the puzzle that needs explanation here is why the electron has any charge at all. Well, the answer to this is simple and that it is a very tiny electrical generator. What is happening within this arrangement of Om particles is that they are moving very rapidly round and round, chasing one another's tails, so to speak. It is this rotation of Om particles that causes a surrounding field of negative charge. Please note that in a later writing I will explain why it is that these Om particles are moving in this fashion but to keep the story simple here, just accept that they do and let us get on with the rest of my explanation here and discuss the mechanics of a proton.
Everyone is familiar with the common toy called a "Slinky". Looking at the shape of a slinky, imagine taking one end of it and pulling it around so that it comes to join the other end. We now have an object that resembles what is usually referred to as a taurus. If we look closely to this taurus shaped object, and making the assumption that our slinky is a very special "super slinky" that has approximately 1,800 windings in it, we will now have a fair representation of a proton. Each winding inside a proton is actually a single electron but instead of sitting side by side, the electrons are connected in such a way that they create a spiral formation, one after another, until you have 1,800 of them just as our super slinky does in the above example.
Just like the electron, these windings are made up of Om particles that are flowing rapidly through this formation, going round and round. Eventually, after doing some 1,800 loops they return to their starting position, much like a stunt pilot who gets a bit carried away doing consecutive loop the loops in the sky to impress his audience.
If one were to examine the electrical field that is being generated by this formation, one would see that at relatively close distance, there is a charge of negative value. But, as one moves away, the charge value flip flops and becomes positive. The reason for this is that each of the individual loops within the proton are the same as an electron and are generating a negative charge field within their close proximity. This field is being generated along the axis that the individual Om particles are revolving around. The bulk of this field is contained within the body of the taurus shape itself. Stepping back it can be seen that there is a larger flow and a secondary axis of movement to consider.
This is the path takes us around and through the central mass of the taurus shape itself. This flow is revolving about the axis that the secondary charge is being generated and is the opposite in value to the charge generated by the individual windings. This axis passes through the central hole of the taurus and is of positive charge. It is the net effect of this charge living in the outer regions surrounding the proton that gives the observed positive charge that we detect when observing the proton interacting with its environment..
Now that I have defined that the proton is simply an arrangement of electrons connected together, I will explain how it is this construction that leads to opposite but equal values of charge for the proton vs. the electron. Looking at a single electron, let us say that the Om particles are moving within it at a specific steady velocity. The distance traveled by an Om particle for it to complete one lap around the electron I will call distance "x". Now, assuming that the Om particles within the proton are moving in the same manner as those within the electron, the distance they will have to travel before they return to their starting position will be about 1,800 times "x". Taking this a step further, if a single rotation of Om particles within an electron yields a charge of -1, we can now safely come to the conclusion that the body of Om particles within the proton, moving at a net rotational velocity 1/1,800 that of an electron but, there being 1,800 times as many of them doing so, results in a net charge of +1. Hence, our measured charges are opposite but equal in value. The other way to look at it is that the body of Om particles completes a single rotation about its axis 1,800 times faster than those within a proton. Again the same result, opposite but equal charge values.
Once that this is understood, we can move on to the next issue and that is why an electron within an atom maintains a certain distance from the proton and doesn't collapse into it. One would logically conclude that since the proton is of positive charge and the electron is of a negative charge that the two should fall into one another in very short order. I am aware that quantum mechanics tries to explain this using what is called the uncertainty principal and that it is just a matter of probability that assigns the location of the electron around the nucleus of the atom, but I have a big problem with this. This "explanation" is no explanation at all. You might as well say that the electron is held out away from the proton by magical fairy dust as by probability. I do have to agree with Einstein fully on this one. God does not play dice with physics.
Looking at the above model of how the electron and proton are formed, another much more logical and mechanically reliable explanation surfaces. That is, since the charge close in to the proton is actually negative, the electron is kept at bay by this repulsive force. When you look at the charge fields surrounding the proton, the negative charge gradually gets weaker the further away from the surface you get and becomes replaced by a positive charge at a certain outlying distance. As one moves away even further, this outlying charge actually increases in strength until there is a maximal point where the charge is at its greatest and then will begin to wane if one moves away yet even further. It is at this point in the space around the proton that the electron is most tightly bound to. Sort of a "grange point" for the electron, if you will.
More complicated atomic structures that involve many protons, and neutrons, and electrons now become more readily understandable in how they behave. The electrons are all whirling about, avoiding one another because they have a like charge, yet are trapped within this certain area of space by the outerlying positive created by the protons packed together in the nucleus. This next begs the question as to why the nucleus is tightly bound together and not blown apart by the like charges that each of the protons posses. I will leave that to another writing, but rest assured that if you are able to accept what I have written so far, I do have a very nice and tidy explanation for this phenomenon as well as many others that seem to defy logic. That is until you look at them in a different light and are willing to throw away your fairy dust.
Albert Dewey
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A conductor is a material that allows electrical current to pass through is because it has many free electrons to act as a transfer medium. Free electrons are electrons that have become dislodged from the outer shell of an atom. If a material cannot support the flow of electrical current, it is called an insulator. Insulators are materials that contain relatively few free electrons.
Some material may or may not pass electricity, depending on their purity. These materials are called semiconductors. Silicon is an example of a material that exhibits the properties of a semiconductor. Silicon by itself holds on to its electrons quite strongly as is naturally neutral: neither a conductor nor an insulator. Silicone with phosphorus impurities, known as N-type silicon, has a negative charge because of its free electrons. Phosphorus has more electrons than does the silicon atom; phosphorus has donor electrons that do not find a place to bind and therefore become free electrons. Silicon containing born impurities, known as P-type silicon, lacks electrons, and that results in a positive charge. Boron has fewer bond electrons that silicon and leaves holes in the silicon's electron structure. The holes behave like a positively charged particle. So when silicon is mixed with phosphorus or boron, the silicon can be made into either an insulator or conductor. This property makes it an ideal material for transistors and other electronic components.
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A solar cell is made of a semiconductor. If you look at some versions of a Periodic Table of elements the semiconductors are identified with a different color. Semiconductors let their outer shell electrons go when just a little energy is applied. Notice that silicon is in this group, silicon is what the majority of today's solar cells are made of. The first time the solar effect was noticed selenium was used, notice it too is in the semiconductor grouping. Also in this semiconductor grouping is boron, in the column to the left of silicon, and phosphorus, to the right of silicon. Just a little bit of these two elements are put into the silicon of the solar cell to make intentional holes and extras so that electrons will flow.
There are two layers of a solar cell. One layer has the silicon/boron semiconductors and is the p-type, the electron poor side. The other layer is the silicon/phosphorus semiconductor and is the n-type, the electron rich side. Where the two layers meet is the p-n junction. Wires are connected on each side such that when the sun hits it the electrons start flowing and a complete circuit is present. All this motion has to do with electrons wanting to find a home; the atoms want full and thereby stable outer electron shells.
The wires that are connected to the solar cell can go to your lights, calculators, or batteries. The more solar cells, the bigger the solar cell, or the more efficient the solar will determine how much current is produced. The relation between the direction of the sun and the solar cell determines whether electron flow is present or not. Unlike batteries with cells that eventually stop working, solar cells continue to work unless broken by other external factors. Unfortunately, solar cells do not store electricity, when the sun shines they are on and the current flows. This is just like the wires of our homes, when we turn on a device the current flows.
Now if you understand the way the solar cell works you can expand to the diode and transistor. The same semiconductor p-n junction concept is used in the making of them. The discovery of all three, solar cells, diodes, and transistors, have their roots in the application of semiconductors. Diodes and transistors enabled the transition from the vacuum tubes of early televisions and radios into the lightweight and streamlined versions we have today. Not to be overlooked is their application in calculators and computers.
Why learn about the semiconductors and the working of the solar cell? Hopefully, with a little understanding of this concept, upgrading to solar lighting or taking on installation of solar panels will not be so intimidating. Remember that the solar cell is used for producing current, the flow of electrons. Passive solar energy is just heat, which is good for water applications, which is another article.
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The properties of the elements exhibit trends and these trends can be predicted with the help of the periodic table. They can also be explained and understood by analyzing the electron configurations of the elements. This is because, elements tend to gain or lose valence electrons to achieve the stable octet formation.
In addition to this activity, there are two other important trends. First, electrons are added, one at a time, moving from left to right across a period. And, as this happens, the electrons of the outermost shell experience increasingly strong nuclear attraction. As a result, the electrons become closer to the nucleus and more tightly bound. The second trend is the moving down a column in the periodic table, where the outermost electrons become less tightly bound to the nucleus. And these trends explain the periodicity observed in the elemental properties of atomic radius, ionization energy, electron affinity, and electronegativity.
But, before going into that we need to know a bit more about the above mentioned terms:
Atomic Radius
The atomic radius of an element is half of the distance between the centers of two atoms of an element that are in contact with each other. Generally, the atomic radius decreases across a period, from left to right and increases down a given group. Therefore, the atoms with the largest atomic radii are located in Group I and at the lower half of groups.
Ionization Energy
Ionization energy or ionization potential is the energy required to completely remove an electron from a gaseous atom or ion. And, the closer and more tightly an electron is bound to the nucleus, the more difficult it is to remove and the higher its ionization energy. Ionization energy is also required to remove a second valence electron from the univalent ion to form the divalent ion, and so on.
Electron Affinity
Electron affinity is the energy change that occurs when an electron is added to a gaseous atom. It reflects the ability of an atom to accept an electron. And the atoms with stronger effective nuclear charge have a greater electron affinity. Therefore, some generalizations can be made about the electron affinities of certain groups in the periodic table. The alkaline earths have low electron affinity values. This is because they have filled sub shells. But, the halogens have high electron affinities because of the addition of an electron to an atom results in a completely filled shell. Noble gases have zero electron affinities, since each atom possesses a stable octet and will not accept an electron readily.
Electro negativity
An atom with higher electro negativity has a great capacity for attracting bonding electrons. Therefore, electro negativity is a measure of the attraction of an atom for the electrons in a chemical bond. It's related to ionization energy. So, electrons with low ionization energies have low electro negativities because their nuclei do not exert a strong attractive force on electrons. And, elements with high ionization energies have high electro negativities. This is because of the strong pull exerted on electrons by the nucleus.
Therefore, electro negativity is dependant on the atomic number. As the atomic number increases, the electro negativity decreases, as a result of increased distance between the valence electron and nucleus. An example of an electropositive element, i.e. one with low electro negativity, is cesium. And an example of a highly electronegative element is fluorine.
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Optical
It is known to be the first invention and the most common o all types of microscopes. This is made with two materials separately, which is plastic or mirror-type. The refractive glass focuses a light into the eye and or another light detector wherein a mirror-type microscope also did the same. A technique called Sarfus is done to boost up the visibility of nanometre films. Another factor is the ultraviolet light who gives an eye detail to an image given by the object. The phase contrast microscopy is a technique used for a light through a translucent specimen and changed the contrast in the image. Now digital microscopes have been used as an upgrade version for the optical microscopes.
Electron
The electron microscope was invented in the year 1940. It consists of an insulator, electron gun, binocular viewer, a photo plate, and control panel. The shape of a cylindrical tube about two meters long. In contrast to the light microscope, the electron microscope visualizes objects using a thin of rapidly moving electrons that interfere with the specimen placed in the tube. The electrons are emitted by the cathode at the top of the tube and then accelerate by the anode. They then pass through a small aperture which forms them into a beam and into the vacuum inside the tube. Because different regions of the specimen are variously transparent to electrons, different amounts of electrons with changed energy passed through these regions. At the end of the tube, the electrons are collected on fluorescent or photographic film or on the screen that generates an image of the specimen. The beam that reaches the film consists of the different amounts of electrons that pass through a particular region of the specimen. This difference is responsible for the contrast in the film. The original image produced by the electron microscope is always black and white. And it is impossible to see directly with the eye.
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Secret #1 The Atomic Number
The atomic is the number of protons in the nucleus of an atom. It is the number of protons that determines the element. The atomic number of hydrogen is "1" and hydrogen has only one proton. The elements are arranged in the periodic table according to the atomic number.
Secret #2 The Modern Periodic Law
The periodic law, first presented by Dmitri Mendeleev and then modified by Henry Moseley, states that the physical and chemical properties of the elements are periodic functions of the atomic number. Which means that there is a repeating pattern in the order of the elements.
Secret #3 The Periods and Families
The seven periods (rows) of the periodic table represent the seven energy levels that the electrons occupy. The eight families (columns) represent the orbital positions of the valence electrons of the elements.
Secret #4 Electron Configuration
The periodic table also accounts for the electron configuration of an electron. The first two families represent the "s" orbitals and the next six families represent the "p" orbitals. It is imperative that you take the time to understand how to write an electron configuration especially for valence electrons.
Secret #5 Valence Electrons
Valence electrons are the electrons occupying the highest energy levels. It is important to master this concept because the valence electrons are the electrons involved in bonding. You determine the valence electrons by counting the "s" and "p" electrons in that period. You can determine that fluorine has seven valence electrons by going to the second period and count over seven times.
How many bonds that fluorine will form is determined by whether fluorine will gain or lose electrons.
Secret #6 The Octet Rule
The octet rule states that atoms tend to gain or lose electrons in order to obtain a noble gas configuration. A noble gas configuration is the most stable situation and nature tends toward stability.
Whether the atom will gain or lose electrons depends on which requires the least energy. Since it will be easier to gain one electron than lose seven, fluorine will tend to gain one electron creating an anion.
So, fluorine will tend to form one bond.
Secret #7 The Driving Force
The driving force behind chemical bonding is the tendency of atoms to gain or lose electrons in order to obtain a noble gas configuration. If an atom requires two electrons to obtain a noble gas configuration then it will gain two electrons by sharing electrons (covalent) or by taking electrons (ionic).
Secret #7.5 Exceptions
It is extremely important that you remain flexible when study chemistry or any science because there are almost always exceptions to the rule. Therefore be prepared for complications or exceptions and learn these exceptions. Don't fight it, just do it.
If you truly want a better understanding of chemistry you must learn the secrets of the periodic table and practice these secrets regularly. I invite you learn more about the "16 must know elements" or chemistry success by going to http://yourChemcoach.com
First, you will need to gather a few tools to help you with your task. You will need a periodic table, the octet rule and a couple of physics concepts. You can get a periodic table from your book, your teacher or online and the octet rule is below.
The Octet Rule:
An element will tend to gain or lose electrons in order to obtain a Noble Gas valence.
Physics Concepts:
Nature tends to move toward a state of lower energy, which basically means nature takes the easy way. Also, you need to remember that opposites attract an likes repel. These two concepts will help you decide whether an element will gain or lose electrons to obtain the Noble gas valence.
Alright, ready to put these tools to work? Good! Lets determine the charge for lithium.
* Find lithium on the periodic table and determine the valence electrons.
* Lithium has 1 valence electron.
Now remember the octet rule and ask, "Is it easier to lose 1 electron and go back to helium or is it easier to gain 7 electrons and move toward neon?"
I hope you answered that it is easier to lose one and go back. So, lithium will tend lose one electron and become a (1+) cation.
Remember, if you lose electrons you become more positive and if you gain electrons you become more negative because electrons are negative.
If the charge of lithium is (1+) then it will have one bond. It really is just that easy.
Should we try another? How about chlorine?
* Find chlorine on the periodic table and determine the valence electrons.
* Chlorine has 7 valence electrons.
Now ask, "Is it easier to gain 1 electron and go toward argon or is it easier to lose 7 electrons and move back to neon?"
That's right it is easier to gain one and move toward argon. So, chlorine will have a (1-) charge and form one bond.
With a little practice you can determine the bonds for most of the elements most of the time. I invite you to get more chemistry information at Mr. Causey's World or http://yourCHEMcoach.com
How is solar energy generated?
Explosions happen called thermonuclear when helium atoms and hydrogen atoms are fused together and then huge bursts of energy are released. Some of this results in radiation which is a free energy source for the solar panels which are homemade. Electrical energy comes when these solar panels are converting this form of radiation which then can be stored in a battery form to be used later on.
Two ways to generate power
1. Direct-Using solar or photovoltaic cells PV the sunlight will be converted into electricity directly.
2. Indirect-Boiling water is an indirect way to use the suns energy so that the steam that is made moves the turbines and then these are used for indirectly providing power in CSP concentrating solar power.
Uses of solar power
Hand held calculators electronic equipment emergency road signs buoys remote solar-powered sensors and also lights in a parking lot. Some boats and experimental vehicles are using solar powered energy now too. One of the best is the solar panels which are placed outside buildings where the solar cell is continuously charged during the daylight so that at night the electricity is then free so that the streets are lit and providing security for everyone. Satellites are using solar panels where the solar cells are providing power for the electrical systems to operate on the satellites.
Science behind the generation of solar power
Solar panels is what is used to generate solar power as they have photovoltaic cells or the common name being solar cells and when they are arranged in a pattern on a grid surface they collect the energy. Silicon is one material used in solar cells and when the solar energy falls on these solar panels the energy generated knocks loose the electrons and then they can be free to flow. The current then is an electric field and the free electrons flow in that direction. Contacts of metal have to be put in place on the bottom and top of the solar cells to draw this current for use externally. The cell made from silicon known as the single-crystal is one solar cell to consider.
Properties of different chemicals are in silicon in the form of crystalline. There are 14 electrons in one atom of silicon and they are set in shells of 3 varieties. Two shells being the inner ones are joined to the nucleus and then are full as the outer shell has 4 electrons. Then there is an outer shell which is short 4 electrons and the silicon atom will be looking for ways to fill up that last shell. To complete the outer shell the 4 electrons will be shared with the near silicon atoms and this process forms a crystalline. This explains crystalline silicon but pure crystalline silicon is such a poor conductor as all the electrons are locked in.
In order to have the solar cells conduct more there are some impurities put into the silicon in order for the solar cells to work properly so these impurities help in this process. An atom of silicon has 5 electrons in its shell which is the outer one. Phosphorous is free and there is 1 electron in phosphorous so that when the silicon atom bonds with its neighbors the phosphorous is then freed. When the heat or energy is also added to this most of these electrons will then go free too so then there are many free carriers produced. This process which takes place when you add impurities is named doping and when the doping of phosphorous into the silicon atom takes place then and only then will the silicon which we will get is then called N for negative or N-type because of the free electrons domination which takes place.
The solar cell then has this N-type but to get another part of the silicon atom it is doped with some boron and this has 3 electrons instead of 4 in the outer shell of it in order to turn it into a P-type silicon. P is for positive where the other one was negative and this P-type actually has free holes. When you put the N-type and the P-type silicons together and the free electrons from the side of N so then this requires some place for the holes to fall into so the free holes on the P-type side and then they rush in to fill up the hole. This then completes the field of electricity which in turn makes our cells of solar power work.
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What keeps the electrons hanging around the nucleus? Well, if you remember the old adage 'like charges repel, unlike attract': electrons have a negative charge, and the nucleus has a positive charge. The flipside of this is that the electrons need energy if they are to avoid spiralling into the nucleus. This was one of the main questions at the beginning of the century: where does this energy come from? The answer turns out to be very counterintuitive: very tiny objects, like atoms, don't behave like we would expect them to, and instead follow the rules of the quantum world. The word 'quantum' implies separateness, and in the case of the atom we find that electrons are actually restricted to be at certain separate energies - an electron could have an amount of energy X, or an amount of energy Y, but it can't have an energy between X and Y. This rules out the electron from spiralling, because in order to spiral, the electron would have to go through the whole gamut of energies all the way down to zero, and that's just not allowed.
That's not all. For each separate energy level, there's only a certain amount of electrons that are allowed to be at that energy. Suppose we give each of the energy levels a number, n, starting from the one with the least energy (and hence closest to the nucleus) n=1. It turns out that n is one of four quantum numbers that, between them, say everything there is to say about an electron. The others are called l, m, and s, and as we shall see, the values that these numbers can have are limited by the first number n. These four numbers determine why there can only be a certain amount of electrons at each energy level n: another major law of the quantum world is that no two electrons can exist in the same atom if they have the same four numbers. It's a little like two ladies turning up at a high society ball with the identical same outfit; you just know somebody's going to have to go home and change.
What do the other three numbers mean? The l and m numbers are 'rotational' quantum numbers and they determine how the electron moves around the nucleus. Before we explain further, we have to interject with another major law of the quantum world, or rather an admission: we can't actually know where exactly the electron is. This is to do with the famous 'uncertainty principle' which I am sure you have heard about, even if you don't know what it means. In fact, the best we can do is say 'Well, there's an x-percent chance it's here, a y-percent chance it's there, a z-percent chance it's somewhere else, and so on...'. That's all. When showing the location of an electron, a common method is to draw an electron 'cloud', shading the cloud thickly in the areas where the electron is more likely to be, and thinly in the areas where it is less likely to be.
The l quantum number tells us a lot about the shape of the cloud for a particular electron. An electron on energy level n can have any value of l from 0 to n-1. We find that the cloud is split into n-l concentric bands around the nucleus, and the shape of these bands is more complex the higher l is (it basically looks like it has been run through with a pizza slicer l times). For l=0 the cloud is just n spherical shells around the nucleus.
We can say that l gives the rotation strength and m gives the angle at which the rotation axis is tilted. m can have any value between -l and l, and the cloud for each value of m (keeping n and l the same) differs only in that it is rotated a little bit around the nucleus. The last number, s, is called spin - as well as going around the nucleus, the electrons also rotate on their own axis! However electrons can only spin like this in two ways (again another quantum law) and so there are only two possible values for the s number.
Now that we know about the four numbers we can now calculate how many electrons can stay at each energy level n. Well if n=1, l has to be 0 and so m has to be zero. The only number left is s and that means only 2 electrons are allowed. However if n=2, then l can be either 0 or 1. If l=0, then we have 2 electrons just like the n=1 case; if l=1 then m can be -1,0 or 1 and so we will have 6 electrons when we take s into account. That leaves 8 in total. In this way we can calculate the number of electrons at every energy level.
In order to save energy, the lower energy levels usually get filled up first - i.e. helium has its two electrons in the n=1 level whereas lithium, with three electrons, fills the n=1 level first and then puts the spare electron in the n=2 level. However as n gets bigger, things get a bit more complicated and you will see electrons being added to energy levels before the level below is completely full.
The author has a Ph.D in particle physics. This is the first in a series of articles exploring the concepts, structure and history of the atom. He is a member of the Sri Chinmoy Centre and is especially interested in the dialogue between the scientific and spiritual perspectives on life.
Various websites and blogs on the internet also have information regarding how solar panels generate electricity and in this article, I aim to explain the whole process in detail. The material that is used to prepare solar panels is the same element that sparked a revolution in the form of the computer industry, i.e., silicon. The various forms in which silicon is used include amorphous, mono crystalline and poly crystalline silicon. However, silicon in its purest form is ideal for use in solar panels.
To get you to properly understand why silicon is the best element to be used, here are some details. Every element has orbitals viz. "s","p","d" and "f". These orbitals together make shells. Every element has something called valence electrons which are basically the number of electrons in the last shell. These valence electrons determine the chemical properties of the element in question.
Silicon has 4 valence electrons. Also, every element's ambition is to try and fill up its last shell with electrons. The maximum number of electrons that can be contained in silicon's last shell are 8 electrons. So Silicon needs 4 more electrons to be satisfied. Silicon does that by bonding with another silicon atom. The 2 silicon atoms share the outermost 4 valence electrons in order to have 8 electrons.
In the case of solar panels, two different plates are used. One of the plates is made up of a combination of silicon and phosphorus. Phosphorus has 5 valence electrons and hence the combination of the two elements leaves one excess electron lying around. The other plate is made up of a combination of silicon and boron. Boron is next to silicon in the periodic table and has 3 valence electrons. The combination of the 2 elements leaves a "lack of an electron". Thus the former plate is negatively charged and the latter plate is positively charged.
This is the basic principle behind why "solar panels generate electricity". Let's take a look at how the photon particles from the sun actually help in making the above process possible. The photons from the sun have energy in them and fall on the solar panels. When this happens, the extra electron in silicon phosphorus gets excited and moves away from the combination and towards the other oppositely charged plate. This plate attracts the free because of the "lack of electrons" and thus as more photons hit the plate, the more electricity is generated. In specific chemical terms, this is how photovoltaic plates or solar panels generate electricity.
A combination of cells such as the one described above results in solar power plants that are capable of generating larger amounts of electricity. Although single solar cells are not of much use since they do not generate a lot of electricity, they are can be used for smaller applications such as in a solar powered watch or in solar powered calculators. Solar panels capable of generating larger amounts of electricity are typically used to provide energy and power to satellites and for other purposes such as setting up huge power plants in deserts so that the energy needs of tens of thousands of people can be satisfied.
Efficiency in these solar panels generating electricity are something that many scientists and researchers are working on as this could lead to people using the tax-free and clean renewable energy that the sun generates in almost all places in the world to reduce their own energy bills or cut costs.
I hope that this article helped you in learning how solar panels generate electricity. Visit my blog below to learn how to create your own do it yourself solar panels and solar heaters.
Andy Jerald is devoted to helping to save the environment and control pollution by using the renewable sources of energy. He generates his own electricity with the help of solar energy at his house. He blogs about his projects. Check it out at Solar Energy Advantages. Also check out a related blog post at Solar Panels Generate Electricity.
So, Lewis dot symbols can be used to determine the charge of the ion formed, the oxidation number and the number of bonds for the element. But an even better use for electron dot symbols is to join them together to form the Lewis structures of molecules or polyatomic ions.
The purpose of Lewis structures is to show the number and kinds of bonds, and the way in which the atoms or ions are connected in the molecule or polyatomic ion. Many of these structures are simple and can be determined by inspection. While, others are a bit more complicated and require some thinking.
Simple Molecules
Many covalent compounds can be drawn by inspection using the valence electrons and the knowledge that covalent bonds are shared bonds. Just determine the Lewis dot structures of the atoms and the number of bonds for each atom. Then pair up the available electrons for the covalent bonds and draw the molecule.
Although, many molecules can be drawn by inspection others require the use of a few rules to help put them together. So, read the following rules carefully and think.
Complex Compounds
Step One
Determine the "skeleton" for the molecule or polyatomic ion.
1. The least electronegative atom is the central atom, except hydrogen which is always a terminal atom.
2. Oxygen atoms do not bond with each other except in O2 and O3 molecules; peroxides; and super peroxides.
3. In oyxacids (ternary acids), hydrogen usually bonds to the oxygen instead of the central atom.
4. For those that have more than one central atom, the most symmetrical skeletons possible are used.
Step Two
Calculate the number of electrons being shared (bonding electrons).
1. Determine the total number of electrons needed for each atom to complete its octet or duet (N).
2. Determine the total number of valence electrons already available (A). Remember to add electrons for negative charges and subtract electrons positive charges.
3. Subtract the electrons available from the electrons needed to get the number or electrons shared (S). S = N - A
4. Divide the shared (S) by two for the number of bonds in the molecule or polyatomic ion. S/2 = bond pairs
Step Three
Place the bonding electrons in the skeleton as shared pairs.
1. Place one pair of electrons between each pair of bonded atoms.
2. If the central atom does not have a complete octet add double or triple bonds as needed.
NOT ALL ELEMENTS FORM DOBLE OR TRIPLE BONDS ONLY C, N, O, P, and S!!
Step Four
Place the leftover electrons (A - S) in the skeleton as lone pairs.
1. Place lone pairs about each terminal atom to complete the octet rule.
2. Leftover electron pairs are placed on the central atom.
3. If the central atom is from the third or higher period, it can accommodate more than four electron pairs (expanded valance).
Although the above rules will help you with Lewis structures, the key to drawing Lewis structures is practice, practice and more practice.
So, I invite you to learn more about chemistry at Mr. Causey's World or http://yourCHEMcoach.com.
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