§-Quick questions
TASPhysicsUnit 3: Gravity and Electromagnetism
Quick questions on Faraday's law and Lenz's law - TCE Physics (Tasmania)
3short 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 magnetic field passes through an area:
What is faraday's law?Show answer
Faraday found that the induced EMF equals the rate of change of flux linkage, where flux linkage is the flux multiplied by the number of turns :
What is finding the direction step by step?Show answer
A reliable method for any TCE direction question is: (1) decide whether the flux through the coil is increasing or decreasing and in which direction; (2) state, by Lenz's law, that the induced current must oppose that change; (3) work out which face of the coil must become a north or south pole to provide the opposition; (4) apply the right-hand grip rule to the windings to read off the current direction, and hence the direction through any external load. Eddy currents in a solid conductor follow the same rule, which is why a magnet dropped through a copper pipe falls slowly: the induced currents oppose its motion.
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