Electromagnetism

• What phenomenon does electromagnetism describe?

  Electric currents produce magnetic fields
• How do electric currents affect magnetic fields in wires?

  They produce their own magnetic fields around them
• What shape do the magnetic field lines take around a wire with current?

  Concentric circles around the wire
• Where are the magnetic field lines closest together around a wire?

  Near the wire where the field is strongest
• What does the direction of the magnetic field depend on?

  The direction of the electric current
• What rule helps determine the direction of the magnetic field?

  The right hand rule
• How do you use the right hand rule to find the magnetic field direction?

  Thumb points current direction, fingers curl field
• What is the direction of the magnetic field for current flowing upwards?

  Anti-clockwise around the wire
• What happens to the magnetic field when current flows in the opposite direction?

  The magnetic field direction reverses
• What shape does the magnetic field take when current flows through a circular coil?

  Ellipses formed by concentric circles
• What is a solenoid?

  A coil of wire with many turns
• How does the magnetic field within a solenoid compare to that of a bar magnet?

  It is strong and uniform like a bar magnet
• What do we call a magnet created by electricity?

  Electromagnet
• When is an electromagnet magnetic?

  Only when current flows through the wire
• What happens to the magnetic field when the power source is turned off?

  The magnetic field disappears
• How can you reverse the direction of the magnetic field in an electromagnet?

  By reversing the current direction
• What happens to the magnetic field lines when the current direction is flipped?

  The direction of the field lines flips
• What is one way to increase the strength of an electromagnet?

  Increase the current flowing through the solenoid
• What is another way to strengthen an electromagnet?

  Increase the number of turns in the coil
• How does the length of the coil affect the strength of the electromagnet?

  Shorter coils with more turns are stronger
• What material can be added to increase the strength of an electromagnet?

  Iron core inside the solenoid
• What happens to the iron core when the solenoid is switched on?

  It becomes an induced magnet
• What happens to the iron core when the current is turned off?

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

  • Increase the current flowing through the solenoid
  • Increase the number of turns in the coil
  • Decrease the length of the coil while keeping turns constant
  • Add an iron core inside the solenoid