What devices use the generator effect?
Alternators (generate AC) and dynamos (generate DC).
How does an alternator generate AC?
As the magnet rotates inside a fixed coil, the magnetic field through the coil changes direction, inducing an alternating potential difference and current.
How does a dynamo generate DC?
the coil rotates in a fixed magnetic field. As the coil rotates, it generates a potential difference in one direction. A split-ring commutator reverses the connections each half-turn, so the current always flows in the same direction.
What is the purpose of a split-ring commutator in a dynamo?
It reverses the coil connections after half a rotation to produce a current that always flows in the same direction.
When is the induced potential difference greatest?
When the coil and magnetic field are parallel — the coil is “cutting” the field lines at the fastest rate.
When is the induced potential difference zero?
When the coil and magnetic field are at right angles — no field lines are being cut.
How can graphs of potential difference against time be used?
To determine the rotation speed: the time between two zero points = half a rotation.
For alternators, what does the rotation speed equal to?
The frequency of the AC
