Drift Velocity and Mobility and Their Relation with Electric Current

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Drift Velocity and Mobility and Their Relation with Electric Current: Overview

This topic covers concepts, such as, Drift Velocity, Mobility of Electron, Relaxation Time of Electron & Variation of Electric Field in Non-uniform Cross-section Wire etc.

Important Questions on Drift Velocity and Mobility and Their Relation with Electric Current

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Two conducting wires X and Y of same diameter but different materials are joined in series across a battery. If the number density of electrons in X is twice that in Y, find the ratio of drift velocity of electrons in the two wires would be:

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Derive an expression for the resistivity of a good conductor, in terms of the relaxation time of electrons.

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Two metallic wires of the same material have the same length but cross-sectional area is in the ratio 1:2. They are connected (i) in series and (ii) in parallel. Compare the drift velocities of electrons in the two wires in both the cases (i) and (ii).

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The number density of free electrons in a copper conductor is  8.5×1028 m3. How long does an electron take drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is 2.0× 10 6 m 2 and is carrying a current of 3.0 A.

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The number density of free electrons in a copper conductor is estimated at   8.5× 10 28 m 3 . How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is   2.0× 10 6 m 2 and it is carrying a current of 3.0 A.

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The relation between current and drift velocity is

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A. The drift velocity of electrons decreases with the increase in the temperature of conductor.
B. The drift velocity is inversely proportional to the area of cross-section of given conductor.
C. The drift velocity does not depend on the applied potential difference to the conductor.
D. The drift velocity of electron is inversely proportional to the length of the conductor.
E. The drift velocity increases with the increase in the temperature of conductor.

Choose the correct answer from the options given below:

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The current in a copper wire is increased by increasing the potential difference between its ends. Which one of the following statements regarding the number of charge carriers per unit volume in the wire and vi, the drift velocity of the charge carriers is correct?

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In the uniform electric field of E=1×104 N C-1, an electron is accelerated from rest. The acceleration of the electron is nearly (Charge of electron q=1.6×10-19 C)

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A metal wire is subjected to a constant potential difference. When the temperature of the metal wire increases, the drift velocity of the electron in it 

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A conductor wire having 1029 free electrons/m3 carries a current of 20A. If the cross-section of the wire is 1 mm2, then the drift velocity of electrons will be 

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Two cylindrical rods of uniform cross-sectional area A and 2A, having free electrons per unit volume 2n and n respectively are joined in series. A constant current I flows through them in steady state. The ratio of the drift velocity of free electrons in the left rod to that of the right rod is VLVR is:
 

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When potential difference across a given copper wire is increase, drift velocity of charge carriers

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The resultant flow of current in a conductor in the absence of electric field is

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The resultant flow of current in a conductor in the absence of electric field is

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A current i is flowing through the wire of diameter d having drift velocity of electrons vd in it. What will be new drift velocity when diameter of wire is made d4?

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When temperature of a metal is increased, its conductivity

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A metal wire carries a charge of 1200 C in 20 minutes. If the area of the cross-section of the wire is 25 mm2 and the material of the metal contains 6.0×1022 free electrons cm-3, the drift velocity of the electrons in the wire is

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A potential difference is applied across the ends of a metallic wire. If the potential difference is doubled, then the drift velocity:

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In ne and vd be the number of electrons and drift velocity in a semiconductor. When the temperature is increased :