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Unit 3: Gravity and Electromagnetism
Quick questions on Electromagnetic induction: WACE Year 12 Physics Unit 3
4short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is magnetic flux?Show answer
Magnetic flux measures how much field passes through a surface,
What are generators?Show answer
An AC generator rotates a coil in a magnetic field. As the coil turns, the angle between the field and the coil normal changes continuously, so the flux varies sinusoidally and the induced emf varies sinusoidally too. The emf is maximum when the coil plane is parallel to the field (flux changing fastest) and zero when the plane is perpendicular (flux momentarily steady at its peak). Slip rings connect the rotating coil to the external circuit, delivering alternating current.
What are transformers?Show answer
A transformer uses a changing flux to transfer energy between two coils on a shared iron core. AC in the primary creates a changing flux that the core carries to the secondary, inducing an emf there. For an ideal transformer the voltages share the turns ratio,
What is stating direction clearly?Show answer
When asked for direction, name the change in flux first, then say the induced current opposes it, and give the current sense (for example clockwise viewed from a stated side). Marks are lost when students quote Faraday's law but never resolve the sign with Lenz's law.
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