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?

  Using a small plot and compass
• In which direction do magnetic field lines go around a bar magnet?

  From north to south
• Why does a compass point to the north?

  Due to Earth's magnetic field
• What is induced magnetism?

  Magnetism created by electric current
• What shape do the magnetic field lines take around a straight wire with current?

  Concentric circles
• How can you determine the direction of the magnetic field around a wire?

  Using the right-hand rule
• What is a solenoid?

  A coil of wire carrying current
• How does a solenoid's magnetic field compare to a bar magnet's field?

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

  Movement caused by magnetic fields and current
• What does Fleming's left-hand rule help predict?

  The direction of force on a conductor
• What do the fingers in Fleming's left-hand rule represent?

  Magnetic field, current, and force
• How does reversing the direction of current affect a wire in a magnetic field?

  It changes the direction of movement
• What is the role of a split ring in a motor?

  To maintain current direction
• What is the formula for calculating the force on a conductor in a magnetic field?

  $F =$$BIL$
• What is the unit of magnetic field strength?

  Tesla
• How does a loudspeaker utilize the motor effect?


  By moving a cone to create sound waves
• What happens when a conductor moves inside a magnetic field?

  A potential difference is induced
• What is the generator effect?

  Inducing current by moving a conductor
• How can you increase the induced potential difference in a generator?

  By increasing the magnetic field strength
• What is the difference between an alternator and a dynamo?

  Alternators produce AC, dynamos produce DC
• What is the function of a transformer?

  To change voltage and current levels
• What happens in a transformer when alternating current flows through the primary coil?

  An alternating magnetic field is created
• How does the number of turns in a transformer affect voltage?

  More turns increase the voltage
• What is the relationship between primary and secondary voltage in a transformer?

  $\frac{V_P}{V_S} =$$\frac{N_P}{N_S}$
• What does the power conservation principle state in transformers?

  Input power equals output power
• What is a step-up transformer?

  Increases voltage with more secondary turns
• What is a step-down transformer?

  Decreases voltage with more primary turns
• Why is a step-up transformer used in power stations?

  To transmit electricity at high voltages
• What voltage is typically used in homes after stepping down?

  230 volts
• What are the key concepts of electromagnetism covered in this material?

  • Bar magnet properties: North and South poles
  • Attraction and repulsion of magnetic poles
  • Magnetic field visualization using compass
  • Induced magnetism from electric current
  • Solenoid and its magnetic field
  • Motor effect and its applications
  • Generator effect and induced potential difference
  • Transformer function and voltage relationships