Magnetism and electromagnetism

• What are the two poles of a magnet?

  North and south
• What do all magnets produce?

  A magnetic field
• What is a magnetic field?

  A region where magnets experience a force
• What materials experience a force in a magnetic field?

  Iron, steel, nickel, and cobalt
• How can you show a magnetic field?

  By drawing magnetic field lines
• In which direction do magnetic field lines go?

  From north to south
• What does the spacing of magnetic field lines indicate?

  The strength of the magnetic field
• Where is the magnetic field strongest?

  At the poles of a magnet
• What type of force exists between a magnet and a magnetic material?

  Always attractive
• What happens when two like poles of a magnet are near each other?

  They repel each other
• What happens when two unlike poles of a magnet are near each other?

  They attract each other
• What is inside a compass?

  A tiny bar magnet
• Why does a compass point north?

  Because the Earth generates its own magnetic field
• What are the two types of magnets?

  Permanent magnets and induced magnets
• What do permanent magnets do?

  Produce their own magnetic field
• What are induced magnets?

  Magnetic materials that become magnets in a field
• What happens to induced magnets when the magnetic field is removed?

  They quickly lose their magnetism
• How can you increase the strength of a magnetic field around a wire?

  By winding the wire into a solenoid
• What happens to the magnetic field inside a solenoid?

  It is strong and uniform
• What is an electromagnet?

  A solenoid with an iron core
• What is the advantage of using an electromagnet?

  It can be switched on and off
• How do electromagnets work in cranes?

  They lift and pick up magnetic materials
• How do electromagnets function in electric motors?

  They act as switches in circuits
• What happens when a current flows through a wire?

  A magnetic field is created around the wire
• How can you visualize the magnetic field around a current-carrying wire?

  By using a compass
• What does changing the direction of the current do?

  It changes the direction of the magnetic field
• What is the right-hand thumb rule used for?

  To determine the direction of the magnetic field
• What increases the strength of the magnetic field in a solenoid?

  Winding the wire into a coil
• What happens to the magnetic field when current stops in a solenoid?

  The magnetic field disappears
• What is the motor effect?

  The interaction of a current-carrying wire and a magnetic field
• What angle must a wire be at to experience the full force in a magnetic field?

  90° to the magnetic field
• How does the force on a wire change with the strength of the magnetic field?

  The force increases with the strength of the field
• What does Fleming's left-hand rule help determine?

  The direction of the force on a conductor
• What happens to a coil of wire in a magnetic field?

  It rotates due to forces acting on it
• What is the function of the split-ring commutator in a motor?

  To keep the motor rotating in the same direction
• How can the direction of a motor be reversed?

  By swapping the polarity of the supply
• How do loudspeakers work?

  They convert electrical signals into sound waves
• What causes the cone in a loudspeaker to move?

  The force on the coil from the current
• How does the frequency of the sound wave relate to the current?

  It is the same as the frequency of the AC
• What is the generator effect?

  The induction of a potential difference