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JEE Main 202227 JulyEvening Shift
Exam
JEE Main
Year
2022
Date
27 July
Shift
Evening Shift
Subject
Physics
Chapter
Current Electricity

JEE Main 2022 · 27 July · Evening Shift · Physics · Current Electricity

A. The drift velocity of electrons decreases with the increase in...

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:

Options

  1. AA and B only
  2. BA and D only
  3. CB and E only
  4. DB and C only

Correct answer

B. A and D only

Step-by-step solution

Drift velocity =(eτm)E= \left(\dfrac{eτ}{m}\right)E

vd=(eτm)(\DeltaVl){v}_{d} = \left(\dfrac{eτ}{m}\right)\left(\dfrac{\DeltaV}{l}\right)

\DeltaV=\DeltaV = Potential difference applied across the wire As temperature increases, relaxation time decreases, hence Vd{V}_{d} decreases.
As per formula, Vd∝1l{V}_{d} ∝ \dfrac{1}{l}

vd=IneA{v}_{d} = \dfrac{I}{neA}, as it is not mentioned that current is at steady state neither it is mentioned that nn is constant for given conductor. So it can't be said that vd{v}_{d} is inversely proportional to AA.

I=neAvd=VR=VρlAI = neA{v}_{d} = \dfrac{V}{R} = \dfrac{V}{ρl}A

vd=eEτm{v}_{d} = \dfrac{eEτ}{m}

ττ decrease with temperature increase.

First and fourth statements are correct.

vd=Vρlne(E=Vl){v}_{d} = \dfrac{V}{ρlne}\left(E = \dfrac{V}{l}\right)

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