`AB` and `CD` are smooth, parallel rails, separated by a distance `L` and inclined to the horizontal at an angle `theta`. A uniform magnetic field of magnitude `B`, directed vertically upwards, exists in the region. `EF` is a conductor of mass `m`, carrying a current `i`. For `EF` to be in equilibrium

(i) `i` must flow from `E` to `F`
(ii) `B i L = m g tan theta`
(iii) `B i L = m g sin theta`
(iv) `B i L = m g`

Options

A. 1 must flow from E to F
B. BIL =mg cos `theta`
C. BIL=mg sin `theta`
D. BIL =mg

Answer

A

Explanation

(1)
N cos `theta=mg`
[`ox` indicates current 1 is flowing into the paper]
N sin `theta` =BIL
`therefore tan theta =(BIL )/(mg)`