Idea 2of 4Builds onOnly change induces
Faster change, bigger swing
Push the magnet in twice as fast. The meter?
Today you'll discover
- what the speed of the change does
- what else makes the swing bigger
- why a generator spins fast
Think firstThe same magnet, pushed in twice as fast
The same magnet is pushed into the same coil twice as fast. How far does the needle swing?
Decide first, then press Next. Compare how far the needle swings at the two speeds.
A magnet, a coil and a meter. After a prediction, the magnet moves in slowly with a small swing of the needle, then twice as fast with a swing twice as far. The last step asks why a bicycle dynamo lamp is brighter at speed.
See the whole ideathe big idea and the key word, in one place
The big idea
The induced voltage follows how fast the field changes.
Compare themStrength of the field: no current on its own. Rate of change of the field: current, and more of it the faster the change.
Key word
- Faraday's law
- the voltage induced in a coil is proportional to how fast the magnetic field through it changes, and to its number of turns
About this modelOnly CHANGE induces: a still magnet, however strong, induces nothing. Faster change, bigger swing.
Only CHANGE induces: a still magnet, however strong, induces nothing. Faster change, bigger swing.
Ready to use it?
- Predict how the induced voltage changes when the speed, the turns, or the magnet change.