magnetic fields of electric currents

• What phenomenon do electric currents produce?

  Magnetic fields
• How do electric currents affect magnetic fields?

  They produce their own magnetic fields
• What happens to the magnetic field around a wire when current flows from bottom to top?

  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?

  The direction of the current
• How can you remember the direction of the magnetic field using your hand?

  Use the right hand rule
• What does curling your fingers in the right hand rule indicate?

  The direction of the magnetic field
• What direction does the magnetic field go when current flows upwards?

  Anti-clockwise
• What happens to the magnetic fields when two wires are joined in a coil?

  They form a single magnetic field
• What shape do the magnetic fields form in a flat circular coil?

  Ellipses
• What is a solenoid?

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

  Strong and uniform inside, weak outside
• What do we call a magnet created by electricity?

  Electromagnet
• What happens to an electromagnet when the current 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
• How does increasing the number of turns in a coil affect its strength?

  It increases the strength of the electromagnet
• What happens if you decrease the length of the coil while keeping the number of turns the same?

  The strength of the electromagnet increases
• What effect does adding an iron core to a solenoid have?

  It increases the strength of the magnetic field
• What type of material is iron in the context of electromagnets?

  Soft magnetic material
• What happens to the iron core when the solenoid is switched on?

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

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

  • Increase the current
  • Increase the number of turns in the coil
  • Decrease the length of the coil
  • Add an iron core
• How do the magnetic fields of a solenoid compare to those of a bar magnet?

  • Solenoid: Strong and uniform inside
  • Bar magnet: Field lines emerge from north, enter south