This diagram shows a rectangular metal frame PQRS placed in a

uniform magnetic field. The magnetic flux density is 4.5 × 10−3 T and the

current in the metal frame is 2.5 A

i. Calculate the force experienced by side PQ of the frame. [1]

ii. Describe the motion of the frame immediately after the current

in the frame is switched on and suggest why side QR does not

experience a force [1]

iii. Calculate the maximum torque (moment) exerted on the frame