JEE PYQ: Magnetic Effects Of Current Question 28
Question 28 - 2020 (09 Jan 2020 Shift 1)
A long, straight wire of radius $a$ carries a current distributed uniformly over its cross-section. The ratio of the magnetic fields due to the wire at distance $\frac{a}{3}$ and $2a$, respectively from the axis of the wire is:
(1) $\frac{2}{3}$
(2) $2$
(3) $\frac{1}{2}$
(4) $\frac{3}{2}$
Show Answer
Answer: (1) $\frac{2}{3}$
Solution
$\frac{B_A}{B_B} = \frac{\mu_0 I/(6\pi a)}{\mu_0 I/(4\pi a)} = \frac{4}{6} = \frac{2}{3}$.
BETA
