A vertical rod of length \( I \) is moved with constant velocity \(...

A vertical rod of length \( I \) is moved with constant velocity \( v \) towards east. The vertical component of earth magnetic field is \( B \) and angle of dip is \( \theta \). The induced e.m.f. in the rod is
(1) \( B N \sin \theta \)
(2) \( B / v \tan \theta \)
(3) \( B N \cot \theta \)
(4) \( B N \cos \theta \)