Concepts Of Physics MCQ Edition [Volume 2]PhysicsMagnetic Field
A current loop of arbitrary shape is situated in a uniform magnetic field B . Determine the net magnetic force exerted on the loop.
Options
- AZero
- BProportional to the loop's area
- CDependent on the shape of the loop
- DProportional to the loop's perimeter
Correct answer
A. Zero
Step-by-step solution
The magnetic force on a small current element d l is given by d F = I(d l B ) . The net magnetic force on the closed loop is F = d F = I(d l B ) . Since the magnetic field B is uniform, it is constant over the loop and can be taken outside the integral. F = I ( d l ) B For any closed loop, the vector sum of the displacement elements is zero, i.e., d l = 0 . Thus, F = I(0) B = 0 . The net magnetic force on any closed current loop in a uniform magnetic field is always zero.