Question

A conducting bar of length L and resistance R is free to slide on frictionless conducting rails of negligible resistance. The circuit is immersed in a uniform and steady magnetic field of strength B. Initially the bar is at rest and the switch is open. The switch is closed. The battery provides a steady voltage V.

a) What is the direction of the current at the instant the switch is closed?

b) What is the magnitude of the current at the instant the switch is closed?

c) If there is a force on any part of the circuit, indicate its direction in the figure and state its magnitude.

d) State why an induced emf ε is expected.

e) In what direction would the induced emf like to drive current? Now suppose that the switch is opened when the bar is moving to the right at speed v.

f) Describe, in detail, what is the subsequent motion of the bar and why. At the instant, after the switch is opened, what are:

g) The induced emf

h) The current in the circuit

i) The power delivered to the resistance R

Answer 1