Question

A steady current flows in a metallic conductor of non-uniform cross section. The quantity/quantities that remain/remains 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 only
• D. current and electric field only
• E. current only

Hint:

In a steady current, current is same through all cross-sections of a conductor, even if the area changes.

Answer 1

Answer: (E)

In steady state, charge does not accumulate anywhere in the conductor. So the current through every cross-section remains the same. For a non-uniform conductor, area changes from point to point. Hence drift speed and electric field can change. Therefore, only current remains constant. \[ \boxed{(E)\ \text{current only}} \]