Question

A current of 5.0 A exists in the circuit shown in the figure. The wire PQ has a length of 50 cm and the magnetic field in which it is immersed has a magnitude of 0.20 T. Find the magnetic force acting on the wire PQ.

Answer 1

Given:
Length of the wire PQ inside the magnetic field, l = 50 cm
Electric current through the wire, I = 5 A
Magnetic field, B = 0.2 T
The direction of magnetic field is perpendicular to the plane of the frame and it is going into the plane of the circuit.
As per the question,

Angle between the plane of the wire and the magnetic field, θ = 90˚
Magnetic force,
`vecF = vecil xx vecB`
`therefore |vecF| = ilBsintheta`
`therefore |vecF| = ilBsin906circ`
= 5 × 50 × 10⁻² × 0.2 × 1
= 0.50 N
The direction of force can be found using Fleming's left-hand rule.
Thus, the direction of magnetic force is upwards in the plane of the paper.