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Moving Charges And Magnetism

Question
CBSEENPH12040129

A metallic rod of mass per unit length 0.5 kg m–1 is lying horizontally on a smooth inclined plane which makes an angle of 30° 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

  • 7.14 A

  • 5.98 A

  • 11.32 A

  • 14.76 A

Solution

C.

11.32 A

For equilibrium,

mg sin 30o = I/B cos 30o I = mglB tan 30o = 0.5 x 9.80.25 x 3 = 11.32 A