Magnetism and Electromagnetism

• What are the two poles of a bar magnet?


  North Pole and South Pole
• What happens when unlike poles of magnets are brought together?


  They attract each other.
• Where is the strongest magnetic field in a bar magnet?


  At the poles.
• How can you visualize the magnetic field around a bar magnet?


  By using a small plot and compass to draw field lines.
• What is the shape of the magnetic field around a bar magnet?


  • Symmetrical
  • Field lines go from North to South
  • Strongest at the poles
• Why does a compass always point to the North?


  Because of the Earth's magnetic field.
• What is created when a current flows through a conductor?


  A magnetic field.
• How do the field lines look around a wire carrying current?


  They form concentric circles around the wire.
• What rule can be used to determine the direction of the magnetic field around a current-carrying wire?


  The right-hand rule.
• What is a solenoid?


  • A coil of wire that carries a current
  • Creates a magnetic field similar to a bar magnet
  • Field lines are close together in the center
• What happens when a current flows through a solenoid?


  It behaves like a bar magnet.
• What is the motor effect?


  The interaction between a magnetic field and a current that causes movement.
• What does Fleming's left-hand rule help to determine?


  The direction of force on a conductor in a magnetic field.
• What does the first finger in Fleming's left-hand rule represent?


  The direction of the magnetic field.
• What does the second finger in Fleming's left-hand rule represent?


  The direction of the conventional current.
• What does the thumb in Fleming's left-hand rule represent?


  The direction of the force experienced by the conductor.
• How does a motor work?


  A coil of wire moves due to the interaction of current and magnetic fields.
• What is the equation to calculate the force on a conductor in a magnetic field?

  $F =$$BIL$
• What do we measure the magnetic field strength in?

  Tesla.
• How does a loudspeaker work?


  It converts electrical energy into sound waves using a coil and a magnet.
• What is the generator effect?


  The induction of a potential difference when a conductor moves in a magnetic field.
• How can you increase the induced potential difference in a generator?


  By increasing the strength of the magnetic field or the speed of movement.
• What is the difference between an alternator and a dynamo?


  An alternator produces alternating current (AC), while a dynamo produces direct current (DC).
• What is the function of a transformer?


  • Changes current and potential difference in a circuit
  • Consists of primary and secondary coils
  • Induces potential difference through alternating magnetic fields
• What happens in a transformer when an alternating current flows through the primary coil?


  It creates an alternating magnetic field that induces a potential difference in the secondary coil.
• What is the relationship between the number of turns in the primary and secondary coils of a transformer and the potential difference?


  The potential difference increases in proportion to the number of turns.
• What is the equation relating the potential differences and number of turns in a transformer?


  $\frac{V_P}{V_S} =$$\frac{N_P}{N_S}$
• What is the equation for power in a transformer?


  $P_P =$$P_S$
• What is a step-up transformer?


  A transformer with more turns on the secondary coil than the primary coil, increasing potential difference.
• What is a step-down transformer?


  A transformer with more turns on the primary coil than the secondary coil, decreasing potential difference.
• Why is a step-up transformer used in the National Grid?


  To increase the potential difference for efficient long-distance transmission.
• Why is a step-down transformer used in homes?


  To reduce the potential difference to a safe level for household use.
• What are the key concepts of electromagnetism covered in this material?


  • Bar magnets and their poles
  • Magnetic fields and their visualization
  • Induced magnetism from current
  • Solenoids and their properties
  • Motor effect and its applications
  • Generator effect and its principles
  • Transformers and their functions