Q 12-04-121JEE MainJEE Main 2023 (13 Apr, Shift 2)Easy
A straight wire AB of mass $40\ \text{g}$ and length $50\ \text{cm}$ is suspended by a pair of flexible leads in uniform magnetic field of magnitude $0.40\ \text{T}$ as shown in the figure. The magnitude of the current required in the wire to remove the tension in the supporting leads is ______ A. (Take $g=10\ \text{m s}^{-2}$)
Numerical value type. Enter your answer.
Answer: 2
The magnetic force must balance the weight: $BIl=mg$.
$$I=\frac{mg}{Bl}=\frac{0.04\times10}{0.4\times0.5}=2\ \text{A}$$
Solution by Sreeraj P, M.Sc Physics