A metallic rod of mass per unit length 0.5 kg `m^(-1)` is lying horizontally on a smooth inclined plane which makes an anlge 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

Options

A. 7.14 A
B. 5.98 A
C. 14.76 A
D. 11.32 A

Answer

D

Explanation

`ilB cos theta = mg sin theta`
`i= (mg)/(lB) tan theta = ((m)/(l)) (g tan theta)/(B)`
`i=0.5 xx (9.8)/(0.25) xx (1)/(sqrt3) = 11.3` amp.