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Magnetic Fields and Charged Particles for A Level Physics

Predict how a magnetic field bends a moving charged particle, then explore what determines the radius of its circular path.

Learning guide and suggested activities

What this tool shows

How charge sign and field direction set the direction of curvature
Why magnetic force changes direction without changing speed or kinetic energy
How velocity stays tangent while magnetic force points towards the circle centre
How flux density, speed and mass-to-charge ratio set orbit radius
How a cyclotron uses magnetic bending and electric acceleration as an extension

OCR A relevance

OCR A Module 6.3.1: Magnetic fields
Force on a current-carrying conductor and moving charge
Charged-particle circular motion

AQA relevance

AQA 7408 sections 3.7.5.1 and 3.7.5.2
Magnetic flux density and Fleming’s left-hand rule
Charged-particle circular motion and the cyclotron

Try these tasks

Predict the path before launching a positive or negative particle.
Reverse the charge or field direction and explain why the curvature reverses.
Change one variable at a time and compare the new radius with the baseline path.
Explain why magnetic force changes direction but not speed or kinetic energy.