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CUET · PHYSICS · PYQ PAPER 2023

A constant voltage is applied across a wire of non-uniform area of cross-section. Which of the followings quantity is independent of the cross-section?

  1. A Drift speed
  2. B Current density
  3. C Drift speed and free electron density
  4. D Free electron density and the charge crossing per unit time.
Verified Solution

Answer & Solution

Correct Answer

(D) Free electron density and the charge crossing per unit time.

Step-by-step Solution

Detailed explanation

The charge crossing per unit time (current \(I\) ) must remain constant throughout the wire to satisfy the law of conservation of charge. Free electron density ( \(n\) ) is an intrinsic property of the material itself and does not change based on the wire's shape or thickness.…