Force on a Current-Carrying Conductor problem 39

The direction of the force on the wire is downwards.

Explanation

Since the reading on the balance is seen to decrease when a direct current is switched on in the wire, the force on the magnet is upwards. Therefore, according to Newton's third law, the direction of the force on the wire is downwards.

The direction of the current in the wire is from B to A.

Explanation

Since the force on the wire is downwards and the magnetic field is from the north pole of the magnet to the south pole, according to Fleming's left-hand rule, the direction of the current in the wire is from B to A.