A steady current flows in a metallic conductor of non-uniform cro… - Vidyadip

MCQ

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

A
Current, electric field and drift speed
B
Drift speed only
C
Current and drift speed
✓
Current only

✓

Answer

Correct option: D.

Current only

d
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 cross-sections. When $j$ is different, then $E$ is also different. Thus $E$ is not constant. The drift velocity ${v_d}$ is given by ${v_d} = \frac{j}{{ne}}=$ different for different $j$ values. Hence only current i will be constant.

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