Which of the following is a difference between an electromagnet and a permanent bar magnet?
  • Electromagnets are stronger
  • Electromagnets can be turned off
  • Permanent magnets are stronger
  • Permanent magnets can be turned off
Which of the following uses an electromagnetic effect?
  • Iron
  • Light bulb
  • Toaster
  • Washing machine
If the current in the wire increases, what happens to the strength of the magnetic field?
  • It decreases
  • It increases
  • It stops the magnetic field
  • No change
A relay is used in:
  • A car ignition
  • An electric bell
  • An electric cooker
  • An iron
A relay uses a small current to:
  • Attract a magnet
  • Repel a magnet
  • Switch off a current
  • Switch on a larger current
Which of the following is NOT true about the magnetic field around a coil of wire carrying a current?
  • Changing the direction of the current will reverse the poles
  • Increasing the number of coils will increase the strength
  • Making the coil wider will increase the strength
  • Putting an iron core into the coil will increase the strength
The magnetic field around a straight wire carrying an electric current has:
  • A circular shape
  • A diamond shape
  • A square shape
  • An oval shape
The magnetic field around a coil of wire carrying current:
  • Is a circular shape
  • Is a diamond shape
  • Is a square shape
  • Is the same shape as around a bar magnet
If the current direction through the wire is reversed, the direction of the magnetic field:
  • Is also reversed
  • Stays in the same direction
  • The current stops flowing
  • There is no magnetic field
An electromagnet on a crane is used in a scrapyard because:
  • It can be turned on and off
  • It can't be turned on and off
  • It is stronger than a permanent magnet
  • It is weaker than a permanent magnet
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