A1.2 m wire carries a current of 10.0 a in a uniform magnetic field of 0.050t. find the magnitude of the magnetic force on the wire.

To calculate we use the formula for a magnetic force in a current-carrying wire expressed as the product of the current, magnetic field and the length of the wire.
 F = I x L x B

where F is the force on the wire, I is the current flowing on the wire, L is the length of the wire and B is the magnetic field.

F = 10.0 A x 1.2 m x 0.050 T
F = 0.60 N

The rocks expand when there hot/warm  and contract when they are cold.