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What do you mean by drift velocity and mobility of a free electron?
Wiki User
∙ 10y ago
Drift velocity Vd = acceleration x relaxation time
So Vd = (E e / m) * t
Now Vd / E is defined as the drift velocity per unit electric field and known to be mobility of free electron
Hence mobility = (e/m) x t
Thus mobility will be different in different material as it depends on relaxation time.
e/m is the specific charge of electron which is a constant value equals to 1.759 x 1011
Wiki User
∙ 10y ago
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What is velocity modulation in klystron?
As we know in klystron tube drift space is assumed to be free of any electric field. Therefore, the high velocity electron emerging in the later period are able to overtake the low velocity electrons leaving the buncher grids. As a result of these actions, the electrons gradually bunch together as they travel down the drift space. This mechanism of variation in electron velocity in the drift space is known as velocity modulation.
What is the effect on the drift velocity of free electrons by decreasing the length and the temperature of wire?
As we know , resistance(R) is directly proportional to length(L) of conductor and resistence(R) is inversely proportional to current (I) and I=nAqv (v is drift velocity) So , if we decrease the length of the conductor , resistance of the conductor will decrease and current(I) will increase and drift velocity of free electrons will increase . And as we know resistance and temperature have direct relation so , by decreasing the temperature resistence will decrease and current will increase . So drift velocity will increase .
Define drift velocity?
it is defined as the average velocity with which the free eloctrons get drifted towards the positive ends of the conductor under the influence of an external electric field applied
Why are some solid materials good thermal insulators while others are good conductors?
The ones that are called conductors, such as copper, and aluminum have many free electrons . free electrons are free to move from one atom to another , they are not closely tied to their nucleus. this flow is called electron drift, in other words current flow. As in a battery where the positive terminal has few electrons, and the negative has millions of electrons. attach a copper wire across them , and you have electron drift (current flow. solid materials such as rubber, plastic or porcelain or any non - metallic material are known as Insulators. They have no free electrons, thus no electron drift (current flow). an example of an insulator are rubber spacers, to make sure the motor cannot be grounded to the steel frame.
What is the difference between free electron theory and nearly free electron theory?
free electron model not take into account the potential neither the electron interaction. nearly free electron take into account the potential.J.C. Aguiar
What is velocity modulation in klystron?
As we know in klystron tube drift space is assumed to be free of any electric field. Therefore, the high velocity electron emerging in the later period are able to overtake the low velocity electrons leaving the buncher grids. As a result of these actions, the electrons gradually bunch together as they travel down the drift space. This mechanism of variation in electron velocity in the drift space is known as velocity modulation.
What is the effect on the drift velocity of free electrons by decreasing the length and the temperature of wire?
As we know , resistance(R) is directly proportional to length(L) of conductor and resistence(R) is inversely proportional to current (I) and I=nAqv (v is drift velocity) So , if we decrease the length of the conductor , resistance of the conductor will decrease and current(I) will increase and drift velocity of free electrons will increase . And as we know resistance and temperature have direct relation so , by decreasing the temperature resistence will decrease and current will increase . So drift velocity will increase .
Define drift velocity?
it is defined as the average velocity with which the free eloctrons get drifted towards the positive ends of the conductor under the influence of an external electric field applied
What is a single negative electric charge that contributes virtually no mass to an atom?
electron ,Believe it is called a FREE electron. Because it is not internally bound to the nucleolus of the atom. in a conductive material , like copper, they are free to drift from one atom to another. if it was not for free electron's ,electricty(current) could not exist.
Why is the mobility of electrons greater than the mobility of holes?
In an intrinsic semiconductor, a few electrons get thermally excited and break from their valence bond to become a free electron. This leaves behind a vacancy in its place called 'hole'. In a P-type semiconductor, B with 3 electrons replaces a Si atom with 4 electrons in the lattice. 3 covalent bonds are formed by B with 3 neighbouring Si. But there is a deficiency of one electron in B for bonding with the 4th Si. This deficiency/vacancy is called a hole. When an electric potential difference is present, the electrons from adjacent valence bond moves into the vacancy near it while moving along the potential. The following represents the movement of valence electron. Terminology: * represents valence electron _ represents hole A is -ve and B is +ve. ..I A * * * _ * * * B .II A * * _ * * * * B III A * _ * * * * * B .IV A _ * * * * * * B I- Hole is at the 4th position. II- At first, the 3rd electron from left shifts right to fill the vacancy and leaves behind a vacancy in its place. The vacancy is at the 3rd position. III- Next, the 2nd electron from left has shifted to the 3rd place and filled up that vacancy but leaves a vacancy at its place. The vacancy is at 2nd position. IV- Now, the 1st electron from left moves to occupy the vacancy at the 2nd position creating another vacancy in its own place. The vacancy is at 1st position. As the electrons moved right, the vacancy moved left. The vacancy is called a hole (just a shorter name for convenience). The movement of holes is really the movement of electron in the valence band. Therefore, the mobility of a hole is indirectly the mobility of valence electrons. Mobility is the velocity acquired per unit electric field. In the intrinsic and N type semiconductors, many free electrons are present i.e. electrons in conduction band which are free to move in the crystal as against valence electrons which can only move in the lattice points. When an electric field is applied, both the valence electrons and the free electrons move in the same direction. The hole direction is opposite to that of valence electron but the mobility is the same, as explained earlier. Even for the same electric field, valence electrons cannot move as freely as the free electrons because its movement is restricted. Therefore, the velocity of valence electrons is less compared to free electrons. In other words, the velocity of holes is less compared to free electrons. This means mobility is also less for a hole compared to free electron. Thus, mobility of a free-electron (often abbreviated as 'electron') is greater than that of a hole (indirectly referring to valence electron).
What is the velocity of an electron with a mass of 9.11 x 10-31 kg at a position with an uncertainty of 5x10-10 m?
Do you mean the free mean path velocity, or the absolute velocity over a specific distance (molecular diffusion)?
In a copper wire of cross section 1 square centimeter in which current of 200A flows in copper there are 8.510to the power of 28 freeelectron per cubic meter .calculate the drift velocity?
The drift velocity is found from the formula; V = I/nqA Where n = 8.5 x10^28 1/mmm (number density of free electrons) q = 1.6 x 10^-19 C (electron charge) I = 200 A (current) A = 1 x10^-4 mm (cross sectional area in square meters) V = drift velocity in meters/sec My calculator is dead so you'll have to do the calculations. Ok, calculator fixed. I get .000147 m/s = 14.7 x 10^-5 m/s
Why are some solid materials good thermal insulators while others are good conductors?
The ones that are called conductors, such as copper, and aluminum have many free electrons . free electrons are free to move from one atom to another , they are not closely tied to their nucleus. this flow is called electron drift, in other words current flow. As in a battery where the positive terminal has few electrons, and the negative has millions of electrons. attach a copper wire across them , and you have electron drift (current flow. solid materials such as rubber, plastic or porcelain or any non - metallic material are known as Insulators. They have no free electrons, thus no electron drift (current flow). an example of an insulator are rubber spacers, to make sure the motor cannot be grounded to the steel frame.
Why does current flow through a conductor explain?
The valence band electrons in a conductor are free to drift as an electron gas filling the conductor, in response to an electrical field imposed across the conductor/
What is the difference between free electron theory and nearly free electron theory?
free electron model not take into account the potential neither the electron interaction. nearly free electron take into account the potential.J.C. Aguiar
Free-electron theory of metals is used for?
write note on free electron theory
How can you get free drift city accounts?
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