Physics (Electromagnets)

• What is the phenomenon whereby electric currents produce their own magnetic fields called?

  Electromagnetism
• What happens when an electric current flows through a wire?

  It produces its own magnetic field
• What shape are the magnetic field lines around a wire with an electric current flowing through it?

  Concentric circles
• Where is the magnetic field strongest around a wire with an electric current flowing through it?

  Near the wire
• What is used to help remember the direction of the magnetic field around a wire with an electric current flowing through it?

  Right hand rule
• How does the direction of the magnetic field around a wire with an electric current flowing through it change when the direction of the current is reversed?

  It is reversed
• What happens to the magnetic field lines when two wires with electric currents flowing through them are joined together to form a coil?

  They form ellipses and combine to form a single magnetic field
• What is formed when a coil with many turns is created?

  A solenoid
• What is the magnetic field like inside a solenoid?

  Strong and uniform
• What is the magnetic field like outside a solenoid?

  Similar to a bar magnet
• What is the north pole of a solenoid?

  Where the field lines come out
• What is the south pole of a solenoid?

  Where the field lines point in
• What happens to the magnetic field of a solenoid when the power source is turned off?

  It disappears
• Why is a small electromagnet weak?

  It produces a weak magnetic field
• How can the direction of the magnetic field of a solenoid be reversed?

  By reversing the direction of the current
• What happens to the magnetic field of an electromagnet with an iron core when the power source is turned off?

  It loses its magnetic field
• What are the four ways to increase the strength of an electromagnet?

  • Increase the current
  • Increase the number of turns
  • Decrease the length of the coil
  • Add an iron core