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A2 · Topic 20

Forces from fields.

How magnetic fields are drawn, the force they exert on currents and on moving charges, the fields that currents make in return, and the way a changing field induces a voltage. Play the five simulations below. The gamified lessons and the topic Paper 4 practice are live below too.

Simulations · live
Interactive · live Magnetic fields and field lines Map the field of a bar magnet, a straight wire and a solenoid, with compasses that line up with the field. Loads only when you launch, so the page stays fast.
Interactive · live Force on a current-carrying conductor F = BIL sinθ with sliders for B, I, L and the angle, and a Fleming's left-hand-rule helper. Loads only when you launch, so the page stays fast.
Interactive · live Force on a moving charge Circular motion with r = mv/BQ, and a velocity selector with crossed E and B fields. Loads only when you launch, so the page stays fast.
Interactive · live Magnetic fields due to currents Two parallel currents that attract or repel, with the field and force shown. Loads only when you launch, so the page stays fast.
Interactive · live Electromagnetic induction A magnet through a coil, with a galvanometer, an e.m.f. trace and the Lenz direction. Loads only when you launch, so the page stays fast.
Paper 4 practice · live
Structured questions · with worked solutions Ten original Paper 4 style questions A full topic set across field lines, forces on conductors and charges, fields due to currents, and induction, linking the lessons within the topic with full worked solutions. Open practice →
Lessons · live
Magnetic fields and field lines → Force on a current-carrying conductor → Force on a moving charge → Magnetic fields due to currents → Electromagnetic induction →
Concept map
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