Question

When a current I is set up in a wire of radius r, the drift velocity is v_d· If the same current is set up through a wire of radius 2 r, the drift velocity will be:

विकल्प

• 4 v_d

• 2 v_d

• v_d/2

• v_d/4

Answer 1

v_d/4

Explanation:

I = n A e v_d or v_d ∝ 1/πr²