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What is the energy band in which free electrons exist?
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What keeps things cooler- plastic wrap or aluminum foil?
A plastic is a an insulator or a bad conductor of heat where as a aluminium is a good conductor of heat.The response to heat by any material lies in it's structural pattern,if more number of free electrons exist in the structural form of the object more will be the conductivity of the material.This pattern can also be explained on the basis of the band theory which states that there exists two band,valence band and conduction band.when the number of the electrons in the conduction band increases the conductivity increases.In case of plastic which is a polymer few free electrons exist as compared to aluminium hence is a insulator where as aluminum is a conductor or the heat energy can easily travel through the foil hence FOR KEEPING THINGS COOLER PLASTIC IS BETTER because the heat energy cannot travel through the plastic and heat up the things
Why semi conductor conductivity increases as temperature increase?
Temprature increase the resistivity of a metal as electrons has to travel further against the thermal temprature as increase in temprature will increase the diffussion of electrons while in semi conductor this is dependent on the electric field intensity and charge carrier either n type or p type.
What is a difference between forbidden energy gap depletion region in semiconductor?
forbidden energy gap or energy gap or band gap or band or Eg is the gap between the top of the valance band and bottom of the conduction band. If we apply the energy equivalent to Eg then the electrons in valance band will jump to the conduction band. Ravinder kumar meena stpi n depletion region is the region in semiconductor where there is depletion of free charge carriers.Ravinder kumar meena stpi n
How can you convert electronic energy to electrical energy?
If, by electronic energy, you mean electrons then you don't convert it- that's what it is. Electricity is the flow of electrons from a negative terminal to a positive. In a wire it is delocalised electrons which are free to move
What is the energy band in which free electrons exist?
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What is the difference between Free Electron Theory and Band Theory of solids?
Free Electron Theory:This theory tells that, metals conduct electricity because of the presence of free electrons in it. The outermost shells of metal atoms will be loosely bound with their nucleus. So the electrons in it are free to move anywhere in the solid.These electrons are called free electrons and they are responsible for the conduction of electricity.Band theory of solids:A solid is assumed to contain many bands in which the electrons in it are packed. The most important are valence band and conduction band. The energy of electrons in these bands will be different.The difference in energies of valence band and conduction band determines whether the solid is a conductor, semi - conductor or insulator.For insulators, the difference between energies of them ( energy gap ) will be very high, and for conductor, these bands overlap each other.The conduction band carries the electrons that conduct electricity, but the valence band has all the electrons in the ground state. Whether they go into the conduction band depends on the temperature and the energy gap between the bands. In a conductor, these bands overlap, and hence many electrons can become conducting. Thus, Band Theory explains distinction between metals and insulators, which Free Electron theory cannot do (since it assumes all valence electrons become conducting). Calculations are be performed to see which materials will have big energy gaps and which will have overlapping bands.
Are free electron in valence band or conduction band?
In semiconductors free electrons are in conduction bands.
What is the difference between the resistance of conductor and insulator?
Conductors allow most, if not all, electricity to pass through it. This is due to "wandering electrons" that aren't tightly bound to the nucleus of the conductor itself.Resistors conduct some, but not all electricity to pass. It somewhat resists it, hence resistors.Insulators do not allow electricity to pass through it due to the electrons being so tightly bound to the nucleus.
What happens when heat is added to pure silicon?
An intrinsic (pure) silicon crystal at room temperature has sufficient heat (thermal) energy for some valence electrons to jump the gap from the valence band into the conduction band, becoming free electrons.
If a pure Si crystal has a million free electrons inside it how many holes does it have.what happens to the no of free electrons and holes if the ambient temperature increases?
If the crystal is pure Si (no dopants or impurities) then the number of free electrons in the conduction band will be equal to the number of holes in the valence band. Each electron leaves behind a hole when it is thermally excited into the conduction band. If the ambient temp. increases, there will be more thermal energy available which will increase both the number electrons and the number of holes.
Is the current in intrinsic semiconductos du to fre electrons or valence electrons and what is the diff between them?
Well intrinsic semiconductor is semiconductor crystal with no impurities in it. In intrinsic semiconductor the electrons in valence band(valence electrons) gain energy(due to thermal enegry) and break free into conduction band(means it become free electrons). As this electron breaks free, a vacancy is created in place of it. It is called as a hole. This hole has a positive charge. So current in semiconductor is due to flow of this free electrons and holes. But this current is very small in magnitude. The difference between free electrons and valenece electrons is that valence electrons are often bonded to other atoms in crystal. But free electrons can freely move throughout the crystal.
What keeps things cooler- plastic wrap or aluminum foil?
A plastic is a an insulator or a bad conductor of heat where as a aluminium is a good conductor of heat.The response to heat by any material lies in it's structural pattern,if more number of free electrons exist in the structural form of the object more will be the conductivity of the material.This pattern can also be explained on the basis of the band theory which states that there exists two band,valence band and conduction band.when the number of the electrons in the conduction band increases the conductivity increases.In case of plastic which is a polymer few free electrons exist as compared to aluminium hence is a insulator where as aluminum is a conductor or the heat energy can easily travel through the foil hence FOR KEEPING THINGS COOLER PLASTIC IS BETTER because the heat energy cannot travel through the plastic and heat up the things
How many valence electrons does insulator have?
It is not the number of valence electrons that an insulator has that is important. It is the way the valence electrons are "arranged" in the structure of the material that matters. If not all the valence electrons of a substance are "involved" in the structure of the material, then these electrons are said to be free electrons. They move about in the substance, and are free to contribute to electron flow. The metals are examples. In contrast with this, if all the electrons are bound up in a material, they are not free to support current flow, and the material is said to be an insulator. Said another way, if the valence electrons in a material are in a Fermi energy level that overlaps the conduction band for that material, the material is a conductor. In an insulator, the valence electrons are all in Fermi energy levels that are below the conduction band for that material, and it is an insulator. Applying a voltage to an insulator will not "lift" the valence electrons up into the conduction band to allow them to support current flow.
Can extrinsic semiconductor conduct at 0 k?
Normally, no electron energy states exist in the band gap, the gap between the valence band and conduction band in a semiconductor. However, if we dope the semiconductor, i.e. add donor (n type) or acceptor (p type) atoms to it, we introduce new electron energy states in the band gap! Take for example silicon, in which we introduce phosphorus, which is a group V element and thus a donor atom. This will introduce extra filled electron states just below the conduction band. Now, this all happens at 0K, so no current can flow (this is logical as electrons don't move at this temperature, even with an electric field applied). But if we raise the temperature e.g. until room temperature at 300K, the electrons gain energy and can jump into the free energy states in the conduction band. These electrons in the conduction band can now conduct electricity.
Why semi conductor conductivity increases as temperature increase?
Temprature increase the resistivity of a metal as electrons has to travel further against the thermal temprature as increase in temprature will increase the diffussion of electrons while in semi conductor this is dependent on the electric field intensity and charge carrier either n type or p type.
What is a difference between forbidden energy gap depletion region in semiconductor?
forbidden energy gap or energy gap or band gap or band or Eg is the gap between the top of the valance band and bottom of the conduction band. If we apply the energy equivalent to Eg then the electrons in valance band will jump to the conduction band. Ravinder kumar meena stpi n depletion region is the region in semiconductor where there is depletion of free charge carriers.Ravinder kumar meena stpi n
