A320-m length of wire stretches between two towers and carries a 120-a current. determine the magnitude of the force on the wire due to the earth's magnetic field of 5.0 ×10−5t which makes an angle of 60 ∘ with the wire.

Information provided:
Length of wire, L = 320 m
Current through the wire, I = 120 Amps
Earth's magnetic field acting on the wire, B = 5.0*10^-5 T
Angle at which the magnetic field acts, Ф = 60°

By definition;
Force on the wire, F = LBI Sin Ф

Substituting;
F = 320*5*10^-5*120*Sin 60 = 1.663 N