Chapter 7: Magnetism and Electromagnetism

Force equation(letters)

BI1

Force equation

magnetic flux density x current x length

South and South

attract

North and South

repel

What is a magnetic field

A region where other magnets or magnetic materials experience a force

magnets produce

magnetic fields

loudspeakers and headphones both use

electromagnets

Find which way a force is acting using

flemings left hand rule

current

in a magnetic field experiences a force

permanent magnet

· The coil surrounds one pole of a(n) ________, and is surrounded by the other pole, so the current causes a force on the coil (which causes the cone to move)

poles north

All magnets have two ________ and south.

motor effect

The ________ can happen when you put a current- carrying wire in a magnetic field.

Compasses

________ show the directions of magnetic fields.

spilt ring commutator

· The ________ is a clever way of swapping the contacts every half turn to keep the motor rotating in the same direction.

magnitude

The ________ (strength) of the force increases with the strength of the magnetic field.

right angles

The force always acts at ________ to the magnetic field of the magnets and the direction of the current in the wire.

coil of wire

Forces act on the side arms of a(n) ________ thats carrying a current.

Output pd of transformer equation

vp/vs = np/ns

Output pf of transformer equation two

vsis = vpip

Step up transformer

step the potential difference up

Step down transformer

step the potential difference down