14
Electromagnets Target To know electromagnets are used in relays, bells and loudspeakers. Saturday 11 June 2022

Magnets L6

Embed Size (px)

DESCRIPTION

magnets and electromagnets lesson 6

Citation preview

Page 1: Magnets L6

Electromagnets

TargetTo know electromagnets are used in

relays, bells and loudspeakers.

Tuesday 11 April 2023

Page 2: Magnets L6

Relays• A relay is a type

of switch.• It allows a small

current in one circuit to control a larger current in another circuit.

Notes

Page 3: Magnets L6

Bells use electromagnets:

This is an electric bell – you cannot see the inside working parts but

you know it contains an electromagnet, a power source (cell) and electrical leads. Try to

work out how these are arranged to make the bell work.

Page 4: Magnets L6

Bells use electromagnets:

Hint 1. There is a cell and an

on/off switch.

Page 5: Magnets L6

Bells use electromagnets:

Hint 2. There an electromagnet.

This one has a horseshoe shaped

electromagnet.

Page 6: Magnets L6

Bells use electromagnets:

Hint 3. The arm of the gong has a piece of iron attached.

It is attracted to the electromagnet when it is

on.

Page 7: Magnets L6

Bells use electromagnets:

Hint 4. The arm of the gong also has a contact switch attached. As the gong strikes it switched the

electromagnet off. Then it springs back to switch it on again. This process repeats itself as the bell rings.

Page 8: Magnets L6

How a bell works.• When the electricity is turned on, the iron

core and coil of wire becomes an electromagnet.

• It then pulls the metal connected to the bell towards it.

• This pulls the hammer onto the bell (it rings) AND disconnects the circuit.

• Which turns off the electromagnet.• The metal bar returns its’ original position.• This completes the circuit again and the

electromagnet switches on again.

Page 9: Magnets L6
Page 10: Magnets L6

Loudspeakers and how they work.

The next slide shows two designs of loudspeakers.

They contain a permanent magnet which is attracted and repelled by a variable electromagnet. The electromagnet is attached to a cardboard cone which vibrates to make variable sounds.

Page 11: Magnets L6
Page 12: Magnets L6

The electric bell.

How can the sound of the bell be made:

(a)Louder?(b)Higher

frequency?

Page 13: Magnets L6

The reed switch.

Write a text message to a friend

to explain how a reed switch works?No more than 30

words!

Page 14: Magnets L6

Car starter motor.

Why is it advisable for a car to have a

relay switch attached to the starter motor?