A wire of length 0.50 m carries a current of 8.0 A. If it experiences a force of 0.40 N, what is the magnetic field strength?

here's the solution for question 12:

Given:
Length of wire, $L = 0.50 \text{ m}$
Current, $I = 8.0 \text{ A}$
Force on the wire, $F = 0.40 \text{ N}$
The wire is at right angles to the magnetic field, so $\theta = 90^\circ$.