4th Sep '25

Schemes of Work

P2
- P2.5
  - Lesson 01 - How could a magnetic field be visualised? Lesson Plan Lesson Title
    - Poles of a magnet
      - Suggested Activity:
        Describe two experiments that can be used to identify the magnetic field pattern of a permanent magnet.
        Describe what would happen if two North seeking Magnetic Poles were placed near each other, two South seeking Poles or one of each.
        Which part of a permanent magnet is the strongest?
        Investigate and draw the shape of the magnetic field pattern around a permanent magnet.
        Investigate the effect that two magnets have on each other in different orientations.
        Equipment Required:
        Bar magnets
        Iron filings
        A3 paper
        Plotting compass
    - The region around a magnet where a force acts on another magnet or on a magnetic material (iron, steel, cobalt and nickel) is called the magnetic field.
    - The force between a magnet and a magnetic material is always one of attraction.
    - When two magnets are brought close together they exert a force on each other.
    - The strength of the magnetic field depends on the distance from the magnet. The field is strongest at the poles of the magnet.
    - Two like poles repel each other.
    - The direction of the magnetic field at any point is given by the direction of the force that would act on another north pole placed at that point.
    - Two unlike poles attract each other.
    - The direction of a magnetic field line is from the north
      (seeking) pole of a magnet to the south(seeking) pole of the magnet.
    - Attraction and repulsion between two magnetic poles are examples of non-contact force.
    - A magnetic compass contains a small bar magnet. The Earth has a magnetic field. The compass needle points in the direction of the Earth's magnetic field.
    - A permanent magnet produces its own magnetic field.
    - Students should be able to describe how to plot the magnetic field pattern of a magnet using a compass.
    - An induced magnet is a material that becomes a magnet when it is placed in a magnetic field.
    - Students should be able to draw the magnetic field pattern of a bar magnet showing how strength and direction change from one point to another.
    - Induced magnetism always causes a force of
      attraction.
    - Students should be able to explain how the behaviour of a magnetic compass is related to evidence that the core of the Earth must be magnetic.
    - When removed from the magnetic field an induced magnet loses most/all of its magnetism quickly.
    - Students should be able to describe the attraction and repulsion between unlike and like poles for permanent magnets
    - Students should be able to describe the difference between permanent and induced magnets.
  - Lesson 02 - How are electromagnets made? Lesson Plan Lesson Title
    - When a current flows through a conducting wire a magnetic field is produced around the wire.
      - Suggested Activity:
        Describe how the magnetic effect of a current can be demonstrated.
        Use the ‘right hand thumb rule’ to draw the magnetic field pattern of a wire carrying an electric current.
        Demonstrate what happens when a foil strip with a current flowing through it is placed in a strong magnetic field. What happens if the direction of the current is reversed?
        Try to demonstrate the shape of the magnetic field by placing a wire through a piece of card with iron filings sprinkled near it. Apply a current through the wire.
        Equipment Required:
        Demo: Conducting Wire
        card
        Iron fillings
        Foil Strip
        Powerpack
        U shaped magnet
        leads
    - The strength of the magnetic field depends on the current through the wire and the distance from the wire.
    - Shaping a wire to form a solenoid increases the strength of the magnetic field created by a current through the wire.
    - The magnetic field inside a solenoid is strong and uniform.
    - The magnetic field around a solenoid has a similar shape to that of a bar magnet.
    - Adding an iron core increases the strength of the
      magnetic field of a solenoid.
    - An electromagnet is a solenoid with an iron core.
    - Students should be able to describe how the magnetic effect of a current can be demonstrated
    - Students should be able to draw the magnetic field pattern for a straight wire carrying a current and for a solenoid (showing the direction of the field)
    - Students should be able to explain how a solenoid arrangement can increase the magnetic effect of the current.
    - (Physics only) Students should be able to interpret diagrams of electromagnetic devices in order to explain how they work.
      - Suggested Activity:
        Give students diagrams of different devices which involve an electromagnet, such as a door bell. Students to explain how the device works.
  - Lesson 03 - What is meant by the motor effect? Lesson Plan Lesson Title
    - When a conductor carrying a current is placed in a magnetic field the magnet producing the field and the conductor exert a force on each other. This is called the motor effect.
      - Suggested Activity:
        Explain what is meant by the motor effect.
        Explain why a motor spins with respect to the magnetic field.
        Make an electric motor and investigate how the speed and direction of rotation can be changed.
        Equipment Required:
        Motor kit
        powerpacks
        leads
    - Students should be able to show that Fleming's left-hand rule represents the relative orientation of the force, the current in the conductor and the magnetic field.
    - Students should be able to recall the factors that affect the size of the force on the conductor.
    - For a conductor at right angles to a magnetic field and carrying a current:
      force = magnetic flux density ? current ? length
      F = B I l
      force, F, in newtons, N
      magnetic flux density, B, in tesla, T
      current, I, in amperes, A (amp is acceptable for ampere) length, l, in metres, m
  - Lesson 04 - How does an electric motor work? Lesson Plan Lesson Title
    - A coil of wire carrying a current in a magnetic field tends to rotate. This is the basis of an electric motor.
      - Suggested Activity:
        Explain why changing the direction of the electric current in an electric motor changes the direction of rotation.
        Explain why changing the polarity of the permanent magnets in the electric motor will change the direction of rotation.
        Recall and use Fleming’s left-hand rule.
        Equipment Required:
        Electric motor kit
        Powerpack
        leads
    - Students should be able to explain how the force on a conductor in a magnetic field causes the rotation of the coil in an electric motor.
  - Lesson 05 - How do loudspeakers and microphones work? Lesson Plan Lesson Title
    - (Physics only) Loudspeakers and headphones use the motor effect to convert variations in current in electrical circuits to the pressure variations in sound waves.
      - Suggested Activity:
        Explain how a moving-coil loudspeaker and headphones work.
        Make a working loudspeaker.
        If an unwanted loudspeaker is available take it apart to show the construction of the speaker and where the magnets and electromagnets are located.
        Equipment Required:
        Make a loudspeaker.
        
        A taken apart loudspeaker to show the construction of the speaker and where the magnets and electromagnets are located.
    - (Physics only) Students should be able to explain how a moving-coil loudspeaker and headphones work.
    - (Physics only) If an electrical conductor moves relative to a magnetic field or if there is a change in the magnetic field around a conductor, a potential difference is induced across the ends of the conductor.
    - (Physics only) If the conductor is part of a complete circuit, a current is induced in the conductor. This is called the generator effect.
    - (Physics only) An induced current generates a magnetic field that opposes the original change, either the movement of the conductor or the change in magnetic field.
    - (Physics only) Students should be able to recall the factors that affect the size of the induced potential difference/induced current.
    - (Physics only) Students should be able to apply the principles of the generator effect in a given context.
    - (Physics only) The generator effect is used in an alternator to generate ac and in a dynamo to generate dc.
    - (Physics only) Students should be able to explain how the generator effect is used in an alternator to generate ac and in a dynamo to generate dc
    - (Physics only) should be able to draw/interpret graphs of potential difference generated in the coil against time.
    - (Physics only) Microphones use the generator effect to convert the pressure variations in sound waves into variations in current in electrical circuits.
    - (Physics only) Students should be able to explain how a moving-coil microphone works.
  - Lesson 06 - How do step-up and step-down transformers work? Lesson Plan Lesson Title
    - (Physics only) Students should be able to apply the equation linking the pds and number of turns in the two coils of a transformer to the currents and the power transfer involved, and relate these to the advantages of power transmission at high potential differences.
      - Suggested Activity:
        Explain how a step-up transformer will increase the potential difference in the secondary coil compared to the primary coil but it will also decrease the current. This happens as the electrical power on both primary and secondary coils remains the same.
        GF: Research why American electricity companies switched from using d.c. to a.c. What are the advantages of sending electricity at high potential differences?
    - (Physics only) A basic transformer consists of a primary coil and a secondary coil wound on an iron core.
      - Suggested Activity:
        Demo:
        Making a transformer
        Institute of Physics: Episode 416 – Generators and transformers
        Equipment Required:
        EW: What are transformers?
        Where are transformers used?
        Draw a labelled diagram of a transformer. Students should be able to label the primary coil, secondary coil and the iron core.
        Describe why an iron core is used in a transformer.
        Why are the wires insulated?
    - (Physics only) Iron is used [for a core] as it is easily magnetised. Knowledge of laminations and eddy currents in the core is not required.
    - (Physics only) The ratio of the potential differences across the primary and secondary coils of a transformer Vp and Vs depends on the ratio of the number of turns on each coil, np and ns .
      EQUATION
    - (Physics only) In a step-up transformer Vs > Vp
    - (Physics only) In a step-down transformer Vs < Vp
    - (Physics only) If transformers were 100 % efficient, the electrical power output would equal the electrical power input.
    - (Physics only) Vs ? Is = Vp ? Ip
      Where
      Vs ? Is is the power output (secondary coil) and
      Vp ? Ip is the power input (primary coil).
      power input and output, in watts, W
    - (Physics only) Students should be able to explain how the effect of an alternating current in one coil in inducing a current in another is used in transformers
    - (Physics only) Students should be able to explain how the ratio of the potential differences across the two coils depends on the ratio of the number of turns on each
  - Lesson 07 - How can a specific output power be generated in a transformer? Lesson Plan Lesson Title
    - (Physics only) Students should be able to calculate the current drawn from the input supply to provide a particular power output
      - Suggested Activity:
        Stretch: Substitution questions relating to the power equations
        Challenge: Questions relating to rearranging the power equation.
        super challenge: Two step questions relating to other equations students need to have memorised.