Topic 7

• What happens to materials when placed in a magnetic field?

  They become magnetic
• What are the main topics covered in magnetism and electromagnetism?

  • Magnetic Fields
  • Types of Magnets
  • Induced Magnet
  • Permanent Magnet
  • Magnetic Materials
  • Generating Electricity
  • Compass
  • Forces (Repulsive and Attractive)
• What is an induced magnet?

  A magnet that becomes magnetic in a field
• What materials are considered magnetic?

  Iron, steel, cobalt, nickel
• How does a current-carrying wire affect its surroundings?

  It induces a magnetic field around it
• What do like poles of magnets do?

  They repel each other
• What do opposite poles of magnets do?

  They attract each other
• In which direction do magnetic field lines point?

  From North Pole to South Pole
• What does the Earth's core being magnetic indicate?

  It shows that the Earth's core is magnetic
• What happens when a coil of wire is rotated through a magnetic field?

  It generates a current
• What is Fleming’s Left Hand Rule used for?

  To determine the direction of force in motors
• What does a solenoid consist of?

  A coil of current-carrying wire
• What is the motor effect?

  Force exerted on a current-carrying conductor
• What is the formula for force in a magnetic field?

  Force (N) = magnetic flux density (T) x current (A) x length (m)
• What do the fingers represent in Fleming's Left Hand Rule?

  • Thumb: Force
  • Index Finger: Field
  • Middle Finger: Current
• What does a coil of wire with current flowing through it produce?

  A magnetic field
• What is the purpose of a compass?

  To point in the direction of Earth's magnetic North
• What are some applications of electromagnetism?

  • Microphones
  • Loudspeakers
  • Dynamo
  • Transformers
• What is a step-down transformer used for?

  To reduce voltage
• What is the National Grid's purpose?

  To distribute electricity efficiently
• What does induced potential refer to?

  Potential induced across a conductor
• How does a microphone work?

  It converts vibrations into current
• What does an alternator generate?

  Alternating current
• What does 100% efficiency in power transfer mean?

  Input power equals output power
• What does the equation $V_1 \times I_1 =$$V_2 \times I_2$ represent?


  Power conservation in transformers
• What does n₁ < n₂ indicate in transformers?

  Step-up transformer with increased voltage
• What does n₁ > n₂ indicate in transformers?

  Step-down transformer with decreased voltage
• What does the term 'efficiency' refer to in electrical systems?

  Ratio of useful output to input power
• What is the role of power lines in the National Grid?

  To carry current at high voltage
• What happens if a conductor or field moves relative to each other?

  A potential is induced across the conductor
• What does the term 'generator effect' refer to?

  Induction of potential through motion
• What is the function of a transformer?

  To change voltage levels
• What does the term 'direct current' refer to?

  Current that flows in one direction
• What does the term 'alternating current' refer to?

  Current that changes direction periodically
• What is the significance of the cone in a loudspeaker?

  It vibrates to produce sound
• What does the term 'microphone coil' refer to?

  Part that converts sound into current
• What is the role of a metal core in a transformer?

  To enhance magnetic coupling
• What does the term 'step-up transformer' indicate?

  Increases voltage from primary to secondary
• What does the term 'step-down transformer' indicate?

  Decreases voltage from primary to secondary
• What is the purpose of the National Grid?

  To distribute electricity across regions