Question

A bar of length 0.7 m slides along metal rails at a speed of 1 m/s. The bar and rails are in a magnetic field of 20 T, pointing out into the page. Calculate the motional emf.

(a) 0.7 V

(b) 7 V

(c) 14 V

(d) 1.4 V

The question was asked during an interview for a job.

My query is from Electromagnetic Induction topic in portion Electromagnetic Induction of Physics – Class 12

Answer 1

Correct choice is (c) 14 V

The best explanation: Length (L) = 0.7 m; Speed (v) = 1 m/s; Magnetic field (B) = 20 T

The required equation E = -vLB   (The negative sign only applies to the direction)

E = 1 × 0.7 × 20

E = 0.7 × 20

E = 14 V

Therefore, the motional emf in the bar and rails is 14 V.