JEE PYQ: Magnetic Effects Of Current Question 32
Question 32 - 2019 (08 Apr 2019 Shift 1)
A circular coil having $N$ turns and radius $r$ carries a current $I$. It is held in the XZ plane in a magnetic field $B\hat{i}$. The torque on the coil due to the magnetic field is:
(1) $\frac{Br^2 I}{\pi N}$
(2) $B\pi r^2 IN$
(3) $\frac{B\pi r^2 I}{N}$
(4) Zero
Show Answer
Answer: (2) $B\pi r^2 IN$
Solution
$|\vec{\tau}| = NIA \times B \sin 90° = NI\pi r^2 B$.
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