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Question: Answered & Verified by Expert
A steady current flows in a metallic conductor of non-uniform cross-section. The quantity/ quantities constant along the length of the conductor is/are
PhysicsCurrent ElectricityJEE Main
Options:
  • A Current, electric field and drift speed
  • B Drift speed only
  • C Current and drift speed
  • D Current only
Solution:
2405 Upvotes Verified Answer
The correct answer is: Current only
If E be electric field, then current density $j=$ $\sigma E$
Also we know that current density $j=\frac{i}{A}$
Hence $j$ is different for different area of crosssections. When $j$ is different, then $E$ is also different. Thus $E$ is not constant. The drift velocity $v_d$ is given by $v_d=\frac{j}{n e}=$ different for different $j$ values. Hence only current $i$ will be constant.

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