Compare the interaction of charged particles moving in magnetic fields

movement of charged particle in:

 Electric field Magnetic field FORCE direction and magnitude of force due to electric field is independent of velocity of charged particle direction of force due to magnetic field is perpendicular to the direction of the velocity of the charged particle and the magnitude of force is directly proportional to the magnitude of the velocity ACCELERATION The acceleration produced by force due to electric field is independent of velocity of charged particle The acceleration produced by  force due to magnetic field is perpendicular to the direction of the velocity of the charged particle and the magnitude of acceleration is directly proportional to the magnitude of the velocity ENERGY As Electric field does work on the charged particle as it moves, there is change in Kinetic and Potential energy. As magnetic field does no work on the charged particle as it moves, there is no change in Kinetic and Potential energy.

Circular motion :

• Force on moving charge due to a magnetic field: F = qvB
• Since the force is always perpendicular to the velocity , it can act as centripetal force for circular motion.
• Centripetal force for uniform circular motion:
• therefore,
• Thus the radius of path of uniform circular motion, of a moving charged particle depends on mass, charge and velocity of the particle and strength of the magnetic field.

Extract from Physics Stage 6 Syllabus © 2017 NSW Education Standards Authority (NESA)