P7

• What is a permanent magnet?

  Produces its own magnetic field
• Where is the magnetic field strongest in a magnet?

  At the poles
• How does magnetic field strength change with distance from a magnet?

  It decreases with distance
• What is a magnetic field?

  Region where magnets experience a force
• How can you tell where the magnetic field is stronger?

  Where field lines are closer together
• What do field lines indicate about a magnetic field?

  Direction of force on a north pole
• What happens to like poles of magnets?

  They repel each other
• What happens to unlike poles of magnets?

  They attract each other
• What type of forces are between magnets?

  Non-contact forces
• What is an induced magnet?

  A magnetic material that becomes a magnet
• Name four non-magnetic materials.

  Candle wax, plant matter, chocolate, grape juice
• Name four magnetic materials.

  Iron, steel, nickel, cobalt
• What happens when an induced magnet is moved away from a permanent magnet?

  It quickly loses its magnetism
• What does a compass needle point towards?

  The direction of the magnetic field
• What is a compass needle?

  A small bar magnet
• What does a compass needle do when not near a magnet?

  Points north to align with Earth's field
• What is the right-hand thumb rule used for?

  To determine magnetic field direction
• What two factors affect magnetic field strength around a current-carrying wire?

  Size of current and distance from wire
• How does twisting a wire into a solenoid affect the magnetic field?

  Increases the magnetic field strength
• What happens to the magnetic fields of each turn of wire in a solenoid?

  They add together
• What is an electromagnet?

  A solenoid with an iron core
• How does an iron core affect a solenoid's magnetic field?

  It increases the magnetic field strength
• Where are electromagnets commonly used?

  In fire alarms and scrap yards
• What is the motor effect?

  Force between a magnet and a conductor
• What are three ways to increase the force in the motor effect?

  Increase current, magnetic field strength, length
• What happens to a coil in an electric motor?

  It experiences opposite forces on each side
• What does alternating current do in loudspeakers?

  Causes the coil to move back and forth
• What is the generator effect?

  Induced potential difference in a moving wire
• How can you induce a potential difference?

  Move the magnet or the wire
• How can you swap the direction of the potential difference?

  Move the magnet or wire in opposite direction
• How can you increase the size of the induced potential difference?

  Increase speed of movement or magnetic field strength
• What does an induced current generate?

  Its own magnetic field
• How does an induced current's magnetic field behave?

  Acts against the change that made it
• What happens when sound waves hit a microphone's diaphragm?

  Diaphragm moves back and forth
• What does the movement of the diaphragm in a microphone cause?

  Coil of wire moves back and forth
• What is generated when the coil in a microphone moves?

  Alternating current
• What do alternators generate?

  Alternating current
• What do dynamos generate?

  Direct current
• What happens to the peak height of a coil in a generator when speed increases?

  It increases
• What is induced in the iron core of a transformer?

  Changing magnetic field