JEE MAIN - Physics (2022 - 28th July Morning Shift - No. 12)
As shown in the figure, a metallic rod of linear density $$0.45 \mathrm{~kg} \mathrm{~m}^{-1}$$ is lying horizontally on a smooth inclined plane which makes an angle of $$45^{\circ}$$ with the horizontal. The minimum current flowing in the rod required to keep it stationary, when $$0.15 \mathrm{~T}$$ magnetic field is acting on it in the vertical upward direction, will be :
{Use $$g=10 \mathrm{~m} / \mathrm{s}^{2}$$}
30 A
15 A
10 A
3 A
Explanation
$$mg \times {1 \over {\sqrt 2 }} = {{ilB} \over {\sqrt 2 }}$$
$$ \Rightarrow i = {{mg} \over {Bl}}$$
$$ = {{0.45 \times 10} \over {0.15}} = 30\,A$$
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