alternators and dynamos

What is an alternator

A coil of wire rotating in a magnetic field, the coil is connected between a commutator which allows the current to pass out of the coil

What does an alternator do

-generate alternating current

Alternators rotate a coil in a magnetic field , as the coil spins a current is induced in the coil,this current changes direction every half turn.

Alternators have slip rings (instead of split ring commutators) and brushes so the contacts don’t swap every half turn so they produce an alternating potential difference

Note

Alternators' and 'dynamos' are different types of generator.

When is the maximum potential difference reached in coil

When the coil is horizontal , at this point the wire is sweeping directly through the magnetic field lines at the fastest possible rate

When does the potential difference in a coil fall to zero

When the coil is vertical this is because the coil is moving parallel to the field at this point the coil is not cutting through the magnetic field lines

NOTE

Bc the two sides of coil is attached to 2 different rings an alternator produces an alternating potential difference and an alternating current

How can u increase the strength of magnetic field

Then we increase the side of the alternating current

How can u increase the size of alternating current

Increase the number of turns on the coil or the area of the coil

What happens if you increase the rotation speed of the coil

We also increase both the size and frequency of the alternating current

What are dynamos and how do they work brief

They generate direct current

Work the same as alternator but they have split ring commutators instead of slip rings

This swaps the connection every half turn to keep the current flowing in the same direction

How do alternators work

1-The coil of wire rotates relative to the magnets, this induces a magnetic field in the coil, which then induces a voltage and current in the coil.

2- the slip rings and brushes mean that the contacts don't swap every half turn (like they do in a motor or dynamo).

3-3This means that they produce an alternating potential difference and an alternating current (a.c.)

4As the coil rotates faster, the peaks of the oscillations get larger, and more frequent.

How do dynamos work

1As the coil of wire spins relative to the magnet, a magnetic field, and hence a voltage and current, is induced in the coil.

2The split ring commutator means that the contacts swap every half turn.

3This means that they produce a direct potential difference and hence a direct current (d.c.). It's called direct currentbecause the current is always flowing in the same direction

4As the coil rotates faster, the peaks of the oscillations get larger and more frequent.

More detail for dynamos

Dynamos have a split ring commutator.

The split ring commutator has two sides separated by gap.

The side of the coil moving down is connected to part A of the split ring communicator. The side of the coil moving up is connected to side B

Because of coil is cutting through the magnetic field lines the potential difference and current is induced.

When the coil is vertical its moving parallel to the magnetic field so the potential difference is zero.

Now the coil has moved around the sides Swap so the side of the coil moving down is still connected to the side A of the split commutator and the side moving up is still connected to part B.

Graph for alternator

Graph for dynamos