A train is moving with a speed of 30 m s–1 NS on the rails separated by 2 m. If the vertical component of earth's field is  8 x 10–5 T, the e.m.f. is

0.0048V 0.048V 0.48V 4.8V

0.0048V

$\xi = Blv = 30\times 2 \times 8 \times 10^{-5}V =0.0048V$