A straight conductor of uniform cross-section carries a current I. Let

1.	A straight conductor of uniform cross-section carries a current I. Let s = specific charge of an electron. The momentum of all the free electrons per unit length of the conductor, due to their drift velocities only, is(a) Is (b) I/s (c) √I/s (d) (I/s)2
Answer» Correct Answer is: (b) I/s I = Avne. No. of free electrons per unit length = 1 x A x n. Momentum of each free electron = mv. ∴ momentum per unit length = Anmv = I/e m = I/(e/m) = I/s.

A straight conductor of uniform cross-section carries a current I. Let s = specific charge of an electron. The momentum of all the free electrons per unit length of the conductor, due to their drift velocities only, is(a) Is (b) I/s (c) √I/s (d) (I/s)2

Answer»

Correct Answer is: (b) I/s

I = Avne. No. of free electrons per unit length = 1 x A x n.

Momentum of each free electron = mv.

∴ momentum per unit length = Anmv = I/e m = I/(e/m) = I/s.