Advertisements
Advertisements
प्रश्न
The potential difference applied across a given conductor is doubled. How will this affect (i) the mobility of electrons and (ii) the current density in the conductor? Justify your answers.
Advertisements
उत्तर
Mobility of electron `mu = (v_d)/E = (v_dl)/V`
as `E = V/l`
Hence, `mu prop 1/V`
If V becomes 2V, the mobility will become half. The current density is given by
`J = n ev_d`
J = `n e.(eVtau)/(ml)`
J = `(n e^2Vtau)/(ml)`
J ∝ V
When V become 2V current density will become twice.
APPEARS IN
संबंधित प्रश्न
Electrons are emitted by a hot filament and are accelerated by an electric field, as shown in the figure. The two stops at the left ensure that the electron beam has a uniform cross-section.
Consider the following statements.
(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
Peltier Effect is caused _______________ .
Consider the following statements.
(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
Thomson Effect is caused _______________ .
The drift velocity of a free electron inside a conductor is ______
The relaxation time τ is nearly independent of applied E field whereas it changes significantly with temperature T. First fact is (in part) responsible for Ohm’s law whereas the second fact leads to variation of ρ with temperature. Elaborate why?
Derive an expression for resistivity of a conductor in terms of the number density of charge carriers in the conductor and relaxation time.
What is the average velocity of electrons when no electric field is present?
When an electric field \[E\] is applied to a conductor, what force direction does an electron of charge \[-e\] experience?
Why can current be established almost instantly even when drift speed is only a few millimetres per second?
