JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Magnetic Effects of Current

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A straight wire AB of mass 40 g and length 50 cm is suspended by a pair of flexible leads in uniform magnetic field of magnitude 0.40 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 ms^{- 2}

Answer: 2

Solution

For the tension in the supporting leads to become zero, the magnetic force on the wire must balance its weight.

For equilibrium:

M g = I ℓ B

Solving for current:

I = \frac{M g}{ℓ B} = \frac{40 \times 1 0 ^{- 3} \times 10}{50 \times 1 0 ^{- 2} \times 0.4} = \frac{0.4}{0.2} = 2 A

JEE Main · 2023 · 13 Apr 2023 · Shift 2 · Integer answer

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