Question

A steady current flow in a metallic conductor of non-uniform cross-section. The quantity/quantities remaining constant along the whole length of the conductor is/are:

• A. current, electric field and drift speed
• B. drift speed only
• C. current and drift speed
• D. current only

Answer 1

Answer: (D)

current only

When a steady current flows in a metallic conductor of non-uniform cross-section then the drift speed is $V_d=I/neA$ and the electric field $E=I/\rho A$
$\Rightarrow V_d\propto \frac{1}{A}$ and $E\propto \frac{1}{A}$
$\Rightarrow$ Only current remains constant.

In a metallic conductor of non-uniform cross-section, only the current remains constant along the entire length of the conductor.