Question

A wheel with 8 metallic spokes each 50 cm long is rotated with a speed of 120 rev/min in a plane normal to the horizontal component of the Earth’s magnetic field. The Earth’s magnetic field at the plane is 0.4 G and the angle of dip is 60°. Calculate the emf induced between the axle and the rim of the wheel.

How will the value of emf be affected if the number of spokes were increased?

Answer 1

If a rod of length ‘l’ rotates with angular speed ω in uniform magnetic field ‘B’

ε = \(\frac{1}{2}\)BI²ω

In case  of earth,s magnetic field B_H =|B_e|cosδ and B_v=|B_e|sinδ

Induced emf is independent of the number of spokes i.e., it remain same