The motor effect and generator effect

What is the motor effect?

When a current carrying conductor is in a magnetic field, the magnet and conductor exert a force on each other.

Where does a force always act at to the magnetic field?

Force always acts at right angles to the magnetic fied of the magnets and to the direction of the current in the wire.

What three things does the force acting on a conductor depend on?

The magnetic flux density, the size of the current through the conductor and the length of the conductor.

What direction does current flow?

Positive to negative.

How can the direction of a motor be reversed in a basic dc motor?

swap polarity of the dc supply (reverse current) or swap the magnetic poles (reverse field).

Generator effect meaning

The induction of a potential difference in a wire which is experiencing a change in the magnetic field.

How can you induce a p.d?

Move a magnet in a coil of wire or move a conductor (wire) in a magnetic field (cutting magnetic field lines).

How can you create alternating current with a magnet?

If you keep the magnet moving backwards and fowards, you produce a potential difference that keeps swapping direction, which produces an alternating current.

Induced current always oppses what?

The change that made it.

How can you increase induced p.d?

Increase speed of the movement by cutting more magnetic field lines in a given time or increasing the strength of magnetic field (so there are more field lines that can be cut).

Describe what happens when you turn a magnet (2 marks)

|As you turn the magnet, magnetic field through the coil changes. This change in the magnetic field induces a p.d which can make a current flow in the wire.

What happens if a magnet is moved inside a coil (elctromagnetic induction)

If a magnet is moved inside a coil a potential difference is induced. If the circuit is complete a current will be induced.

What is an induced magnet?

A material which becomes a magnet when placed in a magnetic field.

What is a relay?

An electromagnetic switch. When switch is closed, the electromagnet turns on.