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 $$g = 10$$ m s$$^{-2}$$.

For the wire to be in equilibrium with zero tension in the supporting leads, the magnetic force must balance gravity.

$$BIL = mg$$

Given: $$m = 40$$ g $$= 0.04$$ kg, $$L = 50$$ cm $$= 0.5$$ m, $$B = 0.40$$ T, $$g = 10$$ m/s².

$$0.40 \times I \times 0.5 = 0.04 \times 10$$

$$0.2I = 0.4$$

$$I = 2 \text{ A}$$

The current required is $$\mathbf{2}$$ A.