Given:
The force on a wire due to a magnetic field is zero.
To find:
The angle between the wire and the magnetic field
Step-by-step explanation:
For a current-carrying wire of length 'l' and carrying current 'i', the force in the presence of an external magnetic field is,

The angle between the current direction and the magnetic field is,

So, the force is zero when

Hence, the angle is zero.