What a learner can do afterwards
- Calculates flux as BA cos theta and flux linkage as the number of turns times the flux
- Finds an induced emf from the gradient of a flux linkage against time graph
- Explains why a coil turning in a steady field still has a changing linkage
1 · Read
Flux is the field threading a loop: B A cos theta, where theta tilts between the field and the loop normal. Edge on, the flux vanishes even in a strong field. With N turns, linkage is N times the flux. Forgetting the tilt or the turn count causes most errors.
Faraday says induced emf equals the rate of change of linkage, with a sign for Lenz. Read emf off the gradient of a linkage against time graph: steep means big emf, flat means none. A linkage falling from 10 to 2 in 4 seconds gives an emf of 2 volts.
A coil turning in a steady field still sees changing linkage, since its projected area swings with the angle. That swing is the heartbeat of every generator. Spin faster, add turns, strengthen the field, or enlarge the area to raise the emf.
Count field times area times turns, price change as emf, and spin the coil to keep it changing.
2 · Watch
Take it off screen
Where it sits
Where this leads
Jobs that lean on this skill. Follow one to see everything it is built on.
8 questions wait behind this lesson, each with its answer explained. Every answer feeds the sky: stars light as they are learned, and dim when it is time to come back.