Question

A semi-circular loop of radius $30\, cm$ wire carries current $6\, A$. An uniform magnetic field $0.5\, T$ is present perpendicular to the plane of the loop. What is the magnitude of force exerted on the wire?

• A. 0.9 N
• B. 1.8 N
• C. 0.8 N
• D. 1.4 N

Answer 1

Answer: (B)

Given, the radius of a circular loop,
$R=30 \times 10^{-2}\, m$
current, $I=6 A$ and magnetic field, $B=0.5 \,T$.
Force exerted on the wire,
$F=I L B \,\sin \,\theta$
$\Rightarrow \, F=6 \times 2 \times 30 \times 10^{-2} \times 0.5 \times \sin 90^{\circ}$
$[\because \theta=90^{\circ}$ and $\sin 90^{\circ}=1]$
$\Rightarrow \, F=1.8\,N$