Question

Complete the given statement, a magnetic field cannot exert a force on a charged particle unless:

• A. there is relative motion between the field and the particle.
• B. the magnetic field and the particle move together.
• C. the particle is moving parallel to the field.
• D. the particle is stationary relative to the magnetic field.
• E. the particle is negatively charged.

Answer 1

The correct option is A there is relative motion between the field and the particle.

Magnetic force on charged particle in a magnetic field is given by $\overrightarrow{F}=q(\overrightarrow{v}\times \overrightarrow{B})$

Thus if there is no relative motion between charged particle and the magnetic field, that is, the velocity $v$ is zero, the magnetic field would exert no force on it.