Question

Explain whether an alpha particle will experience any force in a magnetic field if :(i) it is placed in the field at rest(ii) it moves in the magnetic field parallel to field lines (iii) it moves in the magnetic field perpendicular to field lines.

Answer 1

i) alpha particle will not experience any force in magnetic field if it is placed in the field at rest because force will act only if the particle is in motion
ii) & iii) yes alpha particle will experience force in both cases because the direction of magnetic field has no effect on the magnitude of force experienced by the particle.