When a metal rod of length L placed normal to a uniform magnetic field B is moved at a velocity of v perpendicular to the field, the induced emf across its ends is

$BLv$

The correct answer is Option (2) → $BLv$

Explanation:

When a metal rod of length $ L $ moves with velocity $ v $ perpendicular to a uniform magnetic field $ B $, charges in the rod experience a magnetic force, leading to separation of charges and generation of an emf.

Expression for induced emf:

$ \varepsilon = B L v $

where $ B $ = magnetic field strength, $ L $ = length of the rod, $ v $ = velocity of the rod.

Therefore, the induced emf across its ends is $ \varepsilon = B L v $.