Topic 12-Magnetism and the Motor Effect

• What happens when like poles of magnets are brought together?

  They repel each other.
• What happens when opposite poles of magnets are brought together?

  They attract each other.
• Which materials are typically magnetic?

  Cobalt, Steel, Iron, Nickel.
• What are permanent magnets?

  Always magnetic and have fixed poles.
• Where are permanent magnets commonly used?

  Speakers, compasses, electric generators.
• What are induced magnets?

  Materials that become magnetic when induced.
• How can you create a temporary magnet from an induced magnet?

  By stroking it with a permanent magnet.
• What happens to the domains in a material when it becomes a temporary magnet?

  They align in the same direction.

  
• What is the effect of time or a knock on an induced magnet?

  It loses its magnetism as domains randomize.
• In which direction do magnetic field lines point?

  From North to South.
• How does magnetic field strength change with distance from the magnet?

  It decreases with distance.
• What do plotting compasses show?

  The direction and shape of a magnetic field.
• Why does a freely suspended magnetic compass point North?

  It aligns with Earth's magnetic field lines.
• What is the relationship between Earth's magnetic pole and its geographic pole?

  Earth's North pole is a magnetic South Pole.
• What does current produce around a wire?

  A magnetic field.
• What dictates the direction of the magnetic field produced by a current?

  The right hand rule.
• How does magnetic field strength depend on current size?

  Greater current produces a stronger field.
• How does magnetic field strength vary with distance from the conductor?

  It weakens with greater distance.
• What is the shape of the magnetic field around a solenoid?

  Similar to a bar magnet.
• What happens when you coil a wire in a solenoid?

  It forms a uniform magnetic field.
• How does an iron core affect a solenoid's strength?

  It increases strength by guiding field lines.
• What factors affect the strength of a solenoid's magnetic field?

  Current size, length, area, turns, core material.
• What happens when a wire carrying current is near a magnet?

  It experiences a force due to field interaction.
• How do magnetic forces interact between two magnets?

  They feel attraction or repulsion.
• How does the magnetic field around a wire differ from that between two magnets?

  The wire's field is circular, magnets' is straight.
• How is the force on a wire calculated in a magnetic field?

  Using Fleming's Left Hand Rule.
• What does Fleming's Left Hand Rule help determine?

  The direction of the force felt.
• What is the formula for force in a magnetic field?

  $F =$$BIL$
• What is magnetic flux density measured in?

  Tesla [T].
• What is the role of a coil of wire in a motor?

  It interacts with magnetic fields to rotate.
• What happens to the coil in a motor when current flows through it?

  One side is forced down, the other up.
• How can you determine which side of the coil moves up or down?

  Using the Left Hand Rule.