A light, rigid metallic rod of length is pivoted at one end and lies completely…
PHYSICS · Subjective · CBSE · Physics · Moving Charges and Magnetism · Moving Charges and Magnetism
Problem
A light, rigid metallic rod of length L is pivoted at one end and lies completely inside a region of uniform magnetic field of magnitude B. A steady current I is maintained through the rod. The rod is slowly rotated in its own plane about the pivot so that the angle between the rod and the magnetic field changes from θ1 to θ2.
(a) Using an appropriate physical relation, obtain an expression for the instantaneous magnitude F(θ) of the magnetic force acting on the rod when it makes an angle θ with the field.
(b) Derive an expression for the work W done in rotating the rod quasistatically from θ1 to θ2.
(c) Using your result from part (b), calculate the work required to turn the rod from 0∘ to 90∘ when I=5.0A, L=0.30m and B=0.40T.