Home
Class 12
PHYSICS
(i) With reference to free electron theo...

(i) With reference to free electron theory of conductivity, explain the terms :
(a) Drift speed
(b) Relaxation time
(ii) What is the colour code of a `470Omega` carbon resistance havinf tolerance of `5%` ?

Text Solution

Verified by Experts

Learn the concept of drift speed and relaxation time.
Promotional Banner

Similar Questions

Explore conceptually related problems

With reference to free electron theory of conductivity, explain the terms : (1) Drift speed (2) Relaxation time

What is the colour code of a carbon resistor having a resistance of 470 Omega and a tolerance of 5% ?

(a) Define the term 'conductivity' of a metallic wire. Write its SI unit. (b) Using the concept of free electrons in a conductor, derive the expression for the conductivity of a wire in te'rms of number density and relaxation time. Hence obtain the relation between current density and the applied electric field E.

The value of the resistance of a carbon resistor having the standard colour - coding as shown in the figure is n G Omega pm 5% . What is the value of n ?

Answer the following: (i) Define the term drift velocity . (ii) On the basis of electron drift , derive an expression for resistivity of a conductor in terms of number density of free electrons and relaxation time. On what factors does resistivity of a coductor depend ? (iii) Why alloys like constantan and manganin are used for making standard restores ?

Define drift velocity and relaxation time, with reference to the free electron theory of conductors.

A straight copper-wire of length 100m and cross-sectional area 1.0mm^(2) carries a current 4.5A . Assuming that one free electron corresponds to each copper atom, find (a) The time it takes an electron to displace from one end of the wire to the other. (b) The sum of electrostatic forces acting on all free electrons in the given wire. Given resistivity of copper is 1.72xx10^(-8)Omega-m and density of copper is 8.96g//cm^(3) .

The resistance of the given carbon resistor is (24xx10^6+-5%)Omega . What is the sequence of colours on the strips provided on resistor?

(a) Why do the 'free electrons' , in a metal wire , flowing by themselves' not cause any current flow in the wire ? Define drift velocity' and obtain an expression for the current flowing in a wire, in terms of the 'drift velocity of the free electrons. (b) Use the above expression to show that the 'resistivity ' of the material of a wire is inversely proportional to the 'relaxation time' for the 'free electrons ' in the metal.

A metal rod OA of mann 'm' and length 'r' is kept rotating with a constantangular speed omega in a vertical plane about a horizontal axis at the end O. The free end A is arraged to slide without friction along fixed conduction circular ring in the same plane as that of rotation. A uniform and constant magnetic induction vec(B) is applied perpendicular and into the plane of rotation as shown in the figure below. An inductor L and an external resistance R are connected through a swithch S between the point O and a point C on the ring to form an electrical circuit. Neglect the resistance of the ring and the rod. Initially, the switch is open. (a) What is the induced emf across the teminal of the switch? (b) The switch S is closed at time t=0. (i) Obtain an expression for the current as a function of time. (ii) In the steady state, obtin the time dependence of the torque required to maintain the constant angular speed, given that the rod OA was along th positive X-axis at t=0.