Electromagnet Lesson

Making an Electromagnet

Multiple Choice

A permanent magnet will always be magnetic.

• True

• False

There are other types of magnets too

• An electromagnet works using electricity

• It can be turned on or off

Electromagnets

• An electromagnet is easy to make

• We need a coil of wire and a battery (or low voltage power supply

• We use the wire coil and battery to make an electric current flow through the coil

Switching on and off

• It is easy to switch electricity on and off. This means we can switch an electromagnet on and off

• _{Can you think of any potential uses for a magnet you can turn on and off?}

Switching on and off

• Cranes are used in scrap yards where heavy, metal objects are moved by a electromagnets on the cranes (not hooks)

• In the first picture, the crane driver turns on the electromagnet to lift the old car

• When the car is over the correct position, the driver turns off the magnet to drop the car

An improved electromagnet

• Here is a way to make a stronger electromagnet

• Wrap the wire around a piece of iron called a core

• Iron is a magnetic material. When a current flows in the coil, the iron becomes magnetised making the magnetic field much stronger

• _{Would a wooden core work?}

Multiple Choice

It is a kind of magnet that works only when there is a flow of electricity.

• Electromagnet

• Bar Magnet

• Horse Shoe Magnet

• Magnetite

Multiple Choice

Which of the following is NOT part of an electromagnet?

• wire

• core

• battery

• needles

Multiple Choice

An electromagnet differs from a permanent magnet because

• permanent magnets require an electrical current to produce a field.

• electromagnets can be turned off or weakened by reducing to stopping the flow of current.

• electromagnets only have one pole, while permanent magnets always have two.

• permanent magnets require the movement of electrons, while electromagnets do not.

Multiple Choice

An electromagnet can be strengthened if

• less coils are added to the iron core

• the iron core is removed

• more current runs through the wire

• a nickel or cobalt iron core is used.

Multiple Choice

Electromagnets are ___________________.

• permanent

• instant

• temporary

• stable

Multiple Choice

Which makes an electromagnet work?

• needle

• electricity

• pin

• thumbtacks

Multiple Choice

Which of these forces can be used in a motor?

• magnetism

• wind

• friction

• gravity

Multiple Choice

Which appliance does NOT use electromagnet?

• telephone

• television

• radio

• broom