Magnets

Which of these materials will a magnet attract?

• copper

• rubber

• nickel

• plastic

If you tried to move these magnets closer together, what would you feel?

• a push

• a pull

• no force

• an electric discharge

Which statements about magnets is true?

• all magnets have the same shape and size

• all magnets have a north and south pole

• magnets can attract all objects made of metal

• magnets cannot attract objects through solid substances

Which mixture could you separate with a magnet?

• iron fillings and water

• cobalt strips and iron scraps

• iron fillings and nickel scraps

• aluminum scraps and wood chips

Which of these can be turned on and off?

• bar magnet

• electromagnet

• horseshoe magnet

• refrigerator magnet

To work, an electromagnet must be a part of

• a. a battery

• b. an open circuit

• c. an electric crane

• d. an electric circuit

A student has four items - an iron bar, a light bulb, a battery, and wire. Which of these items does the student need to make an electromagnet?

• battery, iron bar, wire

• battery, light bulb, and wire

• iron bar, light bulb, and wire

• iron bar, light bulb, and battery

Which is a property of electromagnets AND bar magnets?

• include an electric source

• created by an electric current

• have a north pole and a south pole

• have a magnetic field that can be strengthened or weakened

9. A student carries out an investigation with two magnets. The student records his observations in the diagram. Which conclusion do the student's observations support?

• electric current flows in both magnets

• the electromagnet has a stronger magnetic field than the bar magnet

• iron fillings to the electromagnet but not to the bar magnet

• electric current is needed to produce the electromagnet but not the bar magnet

Which if these is a way to make an electromagnet stronger?

• putting a switch in the electrical circuit

• replacing the iron core with a copper core

• replacing the copper wire with plastic wire

• wrapping the wire around the iron core more times