Question

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

Answer 1

Correct Answer - D
From Figure, `I l B cos theta = mg sin theta`
`I = (mg)/(l B) tan theta = ((m)/(l)) (g tan theta)/(B)`
`I = 0.5 xx (9.8)/(0.25) xx (1)/(sqrt(3)) = 11.3 A`