9702 · 20.3
Force on a moving charge — FAQ
Frequently asked questions for 9702 Force on a moving charge. Direct answers first, then deeper explanation — then practise with marking.
How does the magnetic force differ from the electric force on a charged particle?
The magnetic force only acts if the charge is moving and has a velocity component perpendicular to the magnetic field. An electric force acts on any charge (moving or stationary) in an electric field.
Why does a charged particle move in a circle in a uniform magnetic field?
When a charged particle moves perpendicularly to a uniform magnetic field, the magnetic force acts perpendicular to its velocity at all times. This continuously changing force direction provides the centripetal force required for circular motion.
Can the Hall effect be used to determine the type of charge carriers in a material?
Yes, the polarity of the Hall voltage (which side becomes positive or negative) directly indicates whether the charge carriers are positive (holes) or negative (electrons).