Lesson Plan: P2.5.05

Hamble Lesson Observation Plan
Learning About
How do loudspeakers and microphones work?
Keywords:
  • Sound Waves: Longitudinal waves that transfer energy as vibrations in particles. (1)
  • Current: A flow of electrons (charge). (1)
  • Motor effect: The motor effect is the term used when a current-carrying wire in the presence of a magnetic field experiences a force. (1)
  • Loudspeaker: Loudspeakers transform electrical signals into sound. Inside a loudspeaker there is a permanent magnet. An electromagnet attached to the speaker cone is inside the magnet field of the permanent magnet. (1)
Memory Anchor:
Method Precise Learning Objective Linked Question / Activity
(Designed for maximum working out)		 Stepping Stones Pitstop Check
(Thinking Map)
(Physics only) Loudspeakers and headphones use the motor effect to convert variations in current in electrical circuits to the pressure variations in sound waves. (Physics only) How do loudspeakers and headphones use the motor effect?

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.
(Physics only) Students should be able to explain how a moving-coil loudspeaker and headphones work. (Physics only) How do moving coil loudspeakers 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) How are potential differences induced across the ends of conductors?
(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) What is 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) What effect does an induced current have?
(Physics only) Students should be able to recall the factors that affect the size of the induced potential difference/induced current. (Physics only) What factors affect the size of the induced potential difference or induced current?
(Physics only) Students should be able to apply the principles of the generator effect in a given context. (Physics only) What are the principles of the generator effect?
(Physics only) The generator effect is used in an alternator to generate ac and in a dynamo to generate dc. (Physics only) How does the generator effect generate A.C in an alternator? What factors can affect the current in an alternator?
(Physics only) should be able to draw/interpret graphs of potential difference generated in the coil against time. (Physics only) What would the graph showing potential difference generated in the coil against time look like?
(Physics only) Microphones use the generator effect to convert the pressure variations in sound waves into variations in current in electrical circuits. (Physics only) What do microphones convert into variations in current in electrical
(Physics only) Students should be able to explain how a moving-coil microphone works. (Physics only) Explain how a moving-coil microphone works?
(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) How does the generator effect generate D.C in an dynamo?
Links To the Big Ideas
ForcesParticlesEnergyCells