When a steady current flows in a metalic conductor of non-uniform cross section. Which of these quantities is constant along the conductor.
A. Current
B. Electric field
C. Drift speed
D. Current density
E. Potential gradient
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
When a steady current flows in a metallic conductor of non-uniform cross-section then the drift speed is $ V_d = \frac{I}{neA} $
Electric Field $ E = \frac{I}{\rho A}$
$\Rightarrow V_d \propto \frac{1}{A} , E \propto \frac{1}{A}$
Current density $ J = \frac{I}{A} $
Potential gradient also depends area.
Only Current is independent of area. Correct option is A Only.