A current carrying closed loop in the from of a right angle isoseles triangle `ABC` is placed in a unifrom magnetic fild acting along `AB`. If the magnetic force on the arm `BC` is `F`, the force on the arm `AC` is

Options

A. `-F`
B. `F`
C. `sqrt(2) F`
D. `-sqrt(2) F`

Answer

A

Explanation

When a current carrying closed loop is placed in a unifrom magnetic field, it experiences no net force.
`vec(F)_(AB) + vec(F)_(BC) + vec(F)_(CA) = 0`. But `vec(F)_(AB) = 0` as the side `AB` is parallel to magnetic field hence it wil experience no force due to magnetic field.
Hence `vec(F)_(BC) + vec(F)_(CA) = 0 implies vec(F)_(BC) = -vec(F)_(CA)`