A magnet swings in and out of a coil, and the swinging slowly dies down. What happens to the size of the induced EMF as the swinging dies down?
Quinn pedals harder, and the bicycle dynamo's headlamp answers twice over: it glows brighter, and its alternation gets quicker.
Spinning the coil faster changes the output in two ways at once.
When Quinn pedals harder, the dynamo's coil spins faster.
A faster spin sweeps each coil side past the poles faster, so the field through the coil changes faster. A faster change induces a bigger EMF. So the EMF gets larger.
A faster spin also finishes each half-turn sooner. The induced direction reverses every half-turn, so the reversals come sooner too. The EMF alternates more frequently.
The two changes always arrive together. A faster spin cannot give one without the other.
A generator's coil is spun faster. What happens to the size of its EMF?
A generator's coil is spun faster. What happens to how often its EMF alternates?
A hand-crank generator is cranked faster. What happens to the size of its EMF, and to how often it alternates?
A faster spin changes the field through the coil faster, so the EMF gets larger.
A faster spin also finishes each half-turn sooner, so the reversals come more often.
The EMF gets larger and alternates more frequently.
The river slows, and a river turbine's generator coil spins slower. What happens to the output?
A slower spin changes the field through the coil more slowly, so the EMF gets smaller.
A slower spin takes longer over each half-turn, so the reversals come less often.
The EMF gets smaller and alternates less frequently.
Quinn says spinning the coil faster gives a larger EMF that alternates more often. Is Quinn correct?
A generator's coil is spun faster. Which pair of changes is correct?
A hand-crank radio is cranked more slowly. What happens to the size of its EMF?
Between two runs with her bench generator, Zara's meter shows a larger EMF that alternates more often. What did Zara change?