NEET Solved Paper 2018 Question 26
Question: A metallic rod of mass per unit length $ 0.5kgm^{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 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is [NEET - 2018]
Options:
A) $ 14\text{.76 A} $
B) $ 5\text{.98 A} $
C) $ 7\text{.14 A} $
D) $ 11\text{.32 A} $
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Answer:
Correct Answer: D
Solution:
For equilibrium,
$ \text{mg sin30}{}^\circ \text{=I}l\text{B cos 30}{}^\circ $
$ \text{I=}\frac{mg}{lB}\tan 30{}^\circ $ $ =\frac{0.5\times 9.8}{0.25\times \sqrt{3}}=11.32A $
