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^(@)` 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.

Options

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

Answer

A

Explanation

The metallic rod of mass is shown by `ilBcosthetaandmgsintheta`.

To keep rod in stationary,
`mgsintheta=ilBcostheta`
`thereforemg tantheta=ilB`
`thereforei=(mg tantheta)/(lB)`
`thereforei=(m/l)(g tantheta)/B`
`thereforei=(0.5xx9.8xxtan30^(@))/0.25`
`thereforei=(0.5xx9.8xx1)/0.25`
`thereforei=11.316A`
`thereforei~~11.32A`