Question

The force exerted on a current-carrying wire placed in a magnetic field is zero when the angle between the wire and the direction of magnetic field is.

• A. ${180}^o$
• B. ${90}^o$
• C. ${60}^o$
• D. ${15}^o$

Answer 1

The correct option is A ${180}^o$

Answer is A.
A current-carrying wire feels a force in the presence of an external magnetic field. It is found to be $F=BILsin\theta$,
where,
L is the length of the wire,
I is the current, and
$\theta$ is the angle between the current direction and the magnetic field.
As the value of sin 180 degrees is 0, the force exerted on a current-carrying wire placed in a magnetic field is zero when the angle between the wire and the direction of magnetic field is 180 degrees.