Question

A rectangular loop carrying a current $i$ is placed in a uniform magnetic field $B$. The area enclosed by the loop is $A$. If there are $n$ turns in the loop, the torque acting on the loop is given by

• A. $ni(\overline{A}\times \overline{B})$
• B. $ni(\overline{A}.\overline{B})$
• C. $\frac{i(\overline{A}\times \overline{B})}{n}$
• D. $\frac{i(\overline{A}.\overline{B})}{n}$

Answer 1

Answer: (A)

$\overrightarrow{\tau }=\overrightarrow{M}\times \overrightarrow{B}$
$=ni(\overrightarrow{A}\times \overrightarrow{B})$ $(\because \overrightarrow{M}=ni\overrightarrow{A})$