Question

Torque acting on a rectangular coil carrying current ${}^{\prime }{I}^{\prime }$ situated parallel to magnetic field of induction ${}^{\prime }{B}^{\prime }$ having number of turns ${}^{\prime }{n}^{\prime }$ and area ${}^{\prime }{A}^{\prime }$ is

• A. $ni\left(\hat{A}\cdot \hat{B}\right)$
• B. $\frac{nBA}{i}$
• C. $ni\left(A\times B\right)$
• D. $\frac{iBA}{n}$

Answer 1

Answer: (C)

When a current carrying coil is placed in a magnetic field, the coil experienced a torque given by
$\tau =M\times B$
where, $M=$ magnetic moment $=niA$
$\therefore \tau =ni(A\times B)$
where, $n=$ number of turns,
$i=$ current flowing in coil
and $A=$ area of coil