Question

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
• D. current only

Answer 1

Answer: (D)

current only

Answer 2

$i=neAv_d$
Drift speed, $V_d=\frac{1}{neA}\propto \frac{1}{A}$
Therefore, for non-uniform cross-section (different values of A) drift speed will be different at different sections. Only current (or rate of flow of charge) will be same.