Question

A metallic wire having length of $2m$ and weight of $4\times {10}^{-3}N$ is found to remain at rest in a uniform and transverse magnetic field $2\times {10}^{-4}T$. Current flowing through the wire is

• A. 10 A
• B. 5 A
• C. 2 A
• D. 1 A

Answer 1

The correct option is A 10 A

Since the wire is at rest it means that the net force acting of the wire is zero. Hence,

$Weight=MagneticForce$,

$F=IlB$

$⟹I=\frac{F}{lB}$

$⟹I=\frac{4\times {10}^{-3}}{2\times 2\times {10}^{-4}}$

Insert values of respective terms we get,

$I=10$ A