Learning objectives
Define magnetic flux as flux density multiplied by the area at right angles to the field, and use Φ = BA with the weber as its unit.
Use magnetic flux linkage NΦ for a coil of N turns, including a coil whose plane is at an angle to the field.
Describe simple experiments — pushing a magnet into a coil, moving a wire across a field — in which an induced e.m.f. (emf) appears only while the flux is changing, and identify what makes it larger.
State and apply Faraday's law (induced e.m.f. equals the rate of change of flux linkage) and Lenz's law (the direction of the induced e.m.f. acts against the flux change that causes it), linking Lenz's law to conservation of energy.
Calculate the e.m.f. induced in a straight conductor moving through a uniform field (e.m.f. = BLv) and in a coil whose flux linkage changes.
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