magnetism

• What is a magnetic field?


  An area where a magnetic material experiences a force
• What is the difference between permanent and induced (temporary) magnets?


  Permanent magnets always produce their own magnetic field, while induced (temporary)magnets become magnets only when placed in a magnetic field
• What materials are considered magnetic materials?


  Iron, cobalt, and nickel
• What happens to magnetic field lines around a bar magnet?


  They come together at the poles, which have the strongest field
• What is a uniform magnetic field?


  A magnetic field where the strength is the same everywhere
• What is the relationship between like poles of magnets?


  Like poles repel each other
• What is the significance of the right-hand rule in electromagnetism?


  It helps determine the direction of the magnetic field relative to the current
• How can the strength of an electromagnet be increased?


  By increasing the number of coils, the core, or the current
• What is a solenoid?


  An electromagnet created by having a coil of wire
• In a solenoid, what direction do the magnetic field lines run?


  From south to north in the middle
• What does the term 'conventional current' refer to?


  The flow of current from positive to negative
• What is the effect of increasing the current in an electromagnet?


  It increases the strength of the magnetic field
• What happens to magnetic field lines when they are drawn?


  They should never touch or cross
• How does the molten iron core of the Earth contribute to its magnetic field?


  It provides the necessary movement of molten metal to generate a magnetic field
• What are the characteristics of magnetic field lines?


  • Lines should never touch or cross
  • Always draw arrows to indicate direction
  • Lines should spread out in a uniform field
• What are the methods to increase the strength of an electromagnet?


  • Increase the number of coils (more turns of wire)
  • Use a stronger core material
  • Increase the electric current flowing through the wire
• the magnetic field lines are always perpendicular to the direction of motion
• when two magnets are brought together they attract or repel depending on their poles
• What happens when the push switch of an electric bell is closed?


  The current flows through the circuit, activating the electromagnet.
• What occurs when the electromagnet is activated in an electric bell?


  The hammer strikes the bell, creating sound.
• What happens when the circuit is broken in an electric bell?

  The electromagnet turns off and the hammer springs back.
• What is the purpose of an electromagnet in a circuit?


  To switch the circuit on or off.
• How does a current-carrying wire interact with a magnetic field?


  It experiences a force at right angles to both the current and the magnetic field.
• What is the formula for the force experienced by a current-carrying wire in a magnetic field?


  Force = magnetic field strength x length x current.
• How can the force on a wire be increased in a magnetic field?


  By increasing the current flowing through the wire.
• What does Fleming's left-hand rule help determine?


  The direction of force, magnetic field, and current.
• What is the function of a DC motor?


  To convert electrical energy into kinetic energy.
• How does the magnetic field interact with the coil in a DC motor?


  The magnetic field interacts with the current in the coil to produce a force.
• What happens to the current in a coil when the motor rotates 180°?


  The current flows in opposite directions, reversing the force.
• What is the role of a split ring commutator in a motor?


  It changes the direction of the current every half turn.
• What is the motor effect in a magnetic field?


  • A conductor carrying a current in a magnetic field experiences a force.
  • The magnetic field produced by the magnet and the conductor exert forces on each other.
  • The coil spins in opposite directions when the current is reversed.
• What happens when the direction of the current is reversed in a motor?


  The motor experiences a force in the same direction as before.
• What is the principle behind electromagnetic induction?


  It involves converting kinetic energy into electrical energy by moving a coil in a magnetic field.
• What is needed to induce a current in a coil during electromagnetic induction?


  A potential difference must be applied to make the current flow.
• What happens when a magnet moves into a coil of wire?


  An induced potential difference is created in the coil.
• What occurs when the magnet moves in the opposite direction in electromagnetic induction?


  The induced current flows in the opposite direction.
• How can you increase the induced current in a generator?


  By using a stronger magnet or increasing the area of the coils.
• What factors affect the strength of an induced current in a generator?

  • Strength of the magnetic field
  • Area of the coils
  • Number of turns in the coil
  • Speed of the magnet's movement
• size of induced current increased by

  • increasing amount of coils experiencing a changing magnetic field
  • change the magnetic field faster- moving the magnet faster
• Magnet moves into the coil of wire and ammeter registers positive current flow