question_answer

A horizontal straight wire 20m long extending from east to west falling with a speed of 5.0 m/s, at right angles to the horizontal component of the earth's magnetic field \[0.30\times {{10}^{-4}}\,Wb/{{m}^{2}}\]. The instantaneous value of the e.m.f. induced in the wire will be

A) 3 mV

B) 4.5 mV

C) 1.5mV

D) 6.0 mV

Correct Answer: A

Solution :

[a]         \[{{\varepsilon }_{ind}}=Bv\ell =0.3\times {{10}^{-4}}\times 5\times 20\] \[=3\times {{10}^{-3}}\,V=3m\,V\].