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9702 · 20.5

Electromagnetic induction — common mistakes

Common exam mistakes on 9702 Electromagnetic induction. Learn what loses marks, then practise the topic with Examiner’s Ink.

Exam tip 1

Always pay close attention to the direction when applying Lenz's Law. Remember that the induced effect opposes the change that caused it, not necessarily the original field itself. Ensure you use the correct units and distinguish between magnetic flux (Φ\Phi) and magnetic flux linkage (λ\lambda). Sometimes questions might provide flux density and area, requiring you to calculate flux first.

Why is electromagnetic induction so important in daily life?

It's the fundamental principle behind electricity generation in power stations, transformers for changing voltage levels, induction cookers, and many electric motors and generators, powering our modern world.

How do Faraday's Law and Lenz's Law work together?

Faraday's Law tells us the magnitude of the induced EMF, based on the rate of flux change. Lenz's Law provides the direction of the induced EMF or current, stating it always opposes the change in magnetic flux that caused it.

What is the difference between magnetic flux and magnetic flux linkage?

Magnetic flux (Φ\Phi) refers to the magnetic field passing through a single loop or area. Magnetic flux linkage (λ\lambda) is the total flux through all turns of a coil, so λ=NΦ\lambda = N\Phi for a coil with N turns, where N is the number of turns.