Question

A horizontal semi-circular wire of radius $r$ is connected to a battery through two similar springs $X$ and $Y$ to an electric cell, which sends current I through it. A vertically downward uniform magnetic field $B$ is applied on the wire, as shown in the figure. What is the force acting on each spring?

• A. $2\pi rBI$
• B. $\frac{1}{2}\pi rBI$
• C. $BIr$
• D. $2BIr$

Answer 1

Answer: (C)

$F_B=i\times 2r\times B$
$2F=F_B$
$F=irB$