Making Magnets

Which of the followings are the methods to make magnets?

• striking

• stroking

• electrical

• magnetical

What do you called a magnet made by electrical method?

Which ways to increase the magnetism or strength of a magnet in the stroking method?

• use more batteries

• have more coils of wire

• use two direction of stroking

• apply more strokes

Jane strokes a steel rod with a very strong magnet back and forth. Will the steel bar be magnetized and able to attract paper clips?

• yes

• no

What is the use of electromagnets?

• to lift heavy object in crane.

• to make sound in the phone

• to make maglev train move

How do electromagnets differ from regular magnets? 

• They  can be turned off and on 

• Their polarity can be reversed

• Their strength can be changed

• All of the above

This is a picture of a simple electromagnet. How can the electromagnet be made stronger?

• Add more coils of wire to the nail.

• Use more batteries.

• Reverse the poles of the magnet.

• Remove all the coils and the nail.

In order for an electromagnet to be formed, an __________ current must pass through a coil of __________ wrapped around an ________ core.

• wire, iron, electric

• electric, wire, iron

• iron, electric, wire

• excited, hair, apple

Which of the following actions make a magnet become demagnetized or get weaker (lose its strength as a magnet to attract magnetic objects)?

• Heating the magnet.

• Hitting the magnet with a non-magnetic object.

• Dropping the magnet from a height.

• Coiling wires around it and running an electric current through the wire.

Which of the following materials is suitable to be magnetized?

• iron

• gold

• steel

• plastic

• rubber