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Physics · PYQ NEET UG 2018
हिन्दीA metallic rod of mass per unit length \( 0.5\text{ kg m}^{-1} \) is lying horizontally on a smooth inclined plane which makes an angle of \( 30^\circ \) with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction \( 0.25\text{ T} \) is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is
Correct answer · Option 4
\( 11.32\text{ A} \)
Explanation
For equilibrium, magnetic force component balances the gravitational pull: \( ILB\cos\theta = mg\sin\theta \implies I = \frac{(m/l)g\tan\theta}{B} = \frac{0.5 \times 9.8 \times \tan 30^\circ}{0.25} \approx 11.32\text{ A} \).
