Electromagnets

• What does a current flowing through a wire generate?

  A magnetic field
• How does a solenoid affect the magnetic effect of a current?

  It increases the magnetic effect
• What is the magnetic field pattern for a straight wire carrying a current?

  Concentric circles around the wire
• What happens when the switch in an electrical circuit is closed?

  An electric current flows around the circuit
• What does the compass needle do when the current is turned off?

  Lines up with the earth's magnetic field
• What proves that there is a magnetic field around the wire?

  The deflection of a compass needle
• How does the strength of the magnetic field change with the size of the current?

  A larger current produces a stronger field
• What happens to the magnetic field strength as you move further from the wire?

  The strength decreases
• What occurs if the direction of the current is changed?

  The direction of the magnetic field changes
• How do you determine the direction of the magnetic field produced by a wire?

  Using the right hand grip rule
• What shape does coiling the wire create?

  A solenoid
• What type of magnetic field does a solenoid produce?

  A strong and uniform magnetic field
• How does the magnetic field around a solenoid compare to that of a bar magnet?

  It has a similar shape
• How do you find the direction of the magnetic field in a solenoid?

  Using the right hand grip rule
• What increases the strength of the magnetic field in a solenoid?

  Increasing the size of the current
• What effect does increasing the number of turns of the coil have?

  It increases the strength of the magnetic field
• What is an iron core in a solenoid called?

  An electromagnet
• Why are electromagnets useful?

  We can change their magnetic field strength
• How can you turn an electromagnet on or off?

  By changing the size of the current
• What are the three ways to increase the strength of the magnetic field produced by a solenoid?

  • Increase the size of the current
  • Increase the number of turns of the coil
  • Place an iron core inside the solenoid
• What is the right hand grip rule used for?

  • To determine the direction of the magnetic field
  • Place thumb in current direction
  • Fingers curl in magnetic field direction
• How does the magnetic field of a solenoid compare to that of a bar magnet?

  • Similar shape
  • Strong and uniform inside
  • Has distinct north and south poles