Electromagnets

• What phenomenon do electric currents produce?

  Magnetic fields
• How do electric currents produce magnetic fields?

  By flowing through wires and coils
• What happens to the magnetic field when current flows through a wire?

  It forms concentric circles around the wire
• Where is the magnetic field strongest around a wire?

  Closest to the wire
• What does the direction of the magnetic field depend on?

  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 for current flowing upwards?

  Thumb up, fingers curl anti-clockwise
• What happens to the magnetic field if the current direction is reversed?

  The magnetic field direction also reverses
• What occurs when two wires with opposite current directions are joined?

  Magnetic fields form ellipses and combine
• What is a solenoid?

  A coil of wire with multiple turns
• How does the magnetic field within a solenoid compare to outside?

  Strong and uniform inside, weak outside
• What is an electromagnet?

  A magnet created by electric current
• What happens to an electromagnet when the current is turned off?

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

  By reversing the current direction
• What are the four ways to increase an electromagnet's strength?

  Increase current, turns, decrease length, add iron core
• Why does adding an iron core increase an electromagnet's strength?

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

  It loses its magnetic field
• What is the appearance of the magnetic field when viewed from above a coil?

  It looks like concentric circles
• How does the magnetic field of a solenoid compare to that of a bar magnet?

  Similar in shape and direction
• What is the effect of densely packed coils in a solenoid?

  It increases the strength of the electromagnet
• What is the relationship between current and magnetic field strength in an electromagnet?

  Higher current leads to stronger magnetic field
• What happens to the magnetic field lines when the current direction is flipped?

  Field lines and poles also flip direction