Electromagnetic Induction – Magnet, Coil and Galvanometer

PhysicsElectric & Magnetic FieldsAges 17–18

Drag a bar magnet into or out of an N-turn coil connected to a galvanometer, or let the magnet move by itself. The needle deflects in proportion to the rate of change of magnetic flux and reverses when the direction of motion or the pole is reversed; when the magnet is at rest the needle returns to zero. Graphs of the flux Φ(t) and the induced EMF e = −N·ΔΦ/Δt run continuously, and the direction of the induced current given by Lenz's law is shown on the coil.