ELECTRICITY AND MAGNETISM

A temporary magnet made from an iron nail, wire, and a battery is called—

• an electric motor

• a magnetic field

• an electromagnet

• a generator

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All of the following are ways that an electromagnet can be made stronger EXCEPT—

• 
  adding more loops of wire

• changing the direction of the current moving through the wire

• increasing the size of the iron core

• increasing the current moving through the wire

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The shown experiment creates —

• 
  static electricity and an insulator screw

• a conductor and a motor

• current electricity and a magnetic screw

• resistance and a generator

An iron nail wrapped with copper wire and attached to a battery
makes —

• an electromagnet

• a permanent magnet

• a metal magnet

• a compass

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What is one advantage of using electromagnets instead of permanent magnets?

• electromagnets are smaller

• permanent magnets last longer

• electromagnets can be turned on and off

• electromagnets do not have poles

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Bits of paper are attracted to the surface of this balloon. What attracts the paper pieces to the balloon?

• 
  Friction

• 
  Static electricity

• Potential energy

• 
  Magnetism

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NGSS.MS-PS2-3

What force causes two metals to repel or attract?

• Magnetism

• Friction

• Gravity

• Electricity

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The magnetic fields of any magnet are greatest —

• around the middle

• around only the north pole

• around the poles

• around only the south pole

Which options correctly differentiate between the magnetic fields generated by a bar magnet and those generated by an electromagnet?

• The direction of the magnetic field of a bar magnet remains constant, but for an electromagnet it can be changed.

• The poles of a bar magnet can be reversed, but for an electromagnet they remain fixed.

• The strength of the magnetic field of an electromagnet can be varied, but for a bar magnet it remains fixed.

• The magnetic field of a bar magnet can be reduced to zero, but the magnetic field of an electromagnet remains constant.

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Laundry in a clothes dryer often becomes charged with static electricity while drying. Which of these best explains why a clothes dryer often generates static electricity?

• Heat from the dryer charges the air and produces lightning.

• Short circuits in the dryer charge the laundry.

• Electrons are transferred as clothes rub against each other in the dryer.

• Clothes with metal pieces conduct electricity in the dryer.