Brainlag PlusTurning a coil in a field gives a.c. through slip rings or d.c. through a commutator; reading peak, period and frequency off the output graph; and how a moving-coil microphone works.
Turning a coil in a field
Spin a coil between the poles of a magnet and the field through it keeps changing, so a p.d.
is induced. Each half turn the sides of the coil swap over, so the p.d. reverses.
- Alternator: each end of the coil connects to its own slip ring, so the reversing p.d. reaches the circuit: a.c.
- Dynamo: a split-ring commutator swaps the connections every half turn, so the output never goes below zero: d.c. that rises and falls.
One full turn of the coil gives one cycle.
The rest of this lesson and its 9 practice questions are in Plus.
Screen 1 of 4, free to read.
- 9 exam-style questions, marked as you go, each with a worked solution
- Anything you get wrong is saved to your flashcards