Electromagnets and Permanent Magnets Quiz

What is an electromagnet?

• A type of magnet that is always magnetic

• A magnet that can be turned on and off

• A natural magnet found in the earth

• A permanent magnet made of iron

How does an electromagnet work?

• By heating a metal to a very high temperature

• By passing an electric current through a wire wrapped around a metal core

• By placing a metal in a magnetic field

• By rubbing a metal with a magnet

Which of the following is NOT a use of electromagnets?

• In MRI machines

• In electric bells

• In compasses

• In maglev trains

What is the main difference between an electromagnet and a permanent magnet?

• Electromagnets can be made stronger than permanent magnets

• Permanent magnets can be turned on and off

• Electromagnets do not attract metals

• Permanent magnets require electricity to work

Which material is commonly used as the core in an electromagnet?

• Copper

• Aluminum

• Iron

• Lead

What affects the strength of an electromagnet?

• The type of metal core

• The color of the wire

• The temperature of the room

• The shape of the core

Increasing the number of coils in an electromagnet will:

• Decrease its strength

• Increase its strength

• Have no effect on its strength

• Make it a permanent magnet

Which of the following is a characteristic of a permanent magnet?

• It can be easily demagnetized

• It requires an electric current to maintain its magnetism

• It retains its magnetism over time without an external power source

• It is made by wrapping wire around a metal core

What happens when the electric current to an electromagnet is turned off?

• It becomes a permanent magnet

• It loses most of its magnetism

• It becomes stronger

• It reverses its magnetic poles

Why are electromagnets preferred in scrapyard cranes?

• Because they can lift heavier objects than permanent magnets

• Because they can be turned off to drop the scrap metal

• Because they are cheaper than permanent magnets

• Because they do not require electricity