Question

A rod of length L, along east-west direction is dropped from a height H. If B be the magnetic field due to earth at that place and angle of dip is θ, then what is the magnitude of induced emf across two ends of the rod when the rod reaches the earth?

Answer 1

Here, 

length = L, 

Height = H, 

Magnetic field = B 

Angle of dip = θ 

The horizontal component of magnetic field = B cosθ 

B cosθ is the net field that will account for the induced emf in the rod 

So, 

The velocity of the rod after falling a distance H is :

V = \(\sqrt{2gH}\)

∴ Induced emf = Bcosθ x L x \(\sqrt{2gH}\)