JEE PYQ: Magnetic Effects Of Current Question 23
Question 23 - 2020 (06 Sep 2020 Shift 2)
A square loop of side $2a$ and carrying current $I$ is kept in xz plane with its centre at origin. A long wire carrying the same current $I$ is placed parallel to $z$-axis and passing through point $(0, b, 0)$, $(b \gg a)$. The magnitude of torque on the loop about $z$-axis will be:
(1) $\frac{2\mu_0 I^2 a^2}{\pi b}$
(2) $\frac{2\mu_0 I^2 a^2 b}{\pi(a^2 + b^2)}$
(3) $\frac{\mu_0 I^2 a^2 b}{2\pi(a^2 + b^2)}$
(4) $\frac{\mu_0 I^2 a^2}{2\pi b}$
Show Answer
Answer: (4) $\frac{\mu_0 I^2 a^2}{2\pi b}$
Solution
Torque $\tau = \frac{2\mu_0 I^2 a^2 b}{\pi(a^2 + b^2)}$. If $b \gg a$: $\tau \approx \frac{\mu_0 I^2 a^2}{2\pi b}$.
BETA
