A metallic rod of mass per unit length `0.5 kg m^(-1)` is lying horizontally on a straght inclined plane which makes an angle of `30^(@)` with the horizontal. The rod is not allowed to slide down by flowing a current throguh 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. `14.76 A`
B. `11.32 A`
C. `5.89 A`
D. `7.14 A`

Answer

B

Explanation

For stationary rod,

`Bcos thetail=mg sin theta`
`i=(mg tan theta)/(Bl)=(0.5xx10xx1/(sqrt(3)))/(0.25xx1)=20/(sqrt(3)) A =11.32 A`