Loudspeakers (physics Only) (ht Only) (GCSE Physics)

When a loudspeaker is driven by an alternating current, what is the main cause of the audible sound produced in the air?

When voice-coil current is suddenly interrupted while the coil is moving in the magnet gap, an emf is induced across the coil which opposes the change. What practical effect does that induced emf have on coil motion?

When the alternating current in a loudspeaker coil is reversed, what happens to the instantaneous magnetic force on the coil?

What is the main purpose of the permanent magnet in a moving-coil loudspeaker?

Which factor will increase the magnitude of induced emf in a coil when it moves in a magnetic field?

Which of the following describes why a tweeter is often mounted on a small stiff dome rather than a large paper cone?

How does the cone area affect the acoustic output (sound pressure level) produced by a given cone acceleration?

A small section of voice-coil wire of length 0.65 m carries current 0.020 A in a field of 0.125 T. Use F = BIL to calculate the force and identify which option lists the correct calculation (showing the correct numeric result).

What design reason explains using a soft-iron pole piece and laminated magnetic structure around the loudspeaker gap (instead of a solid thick metal block)?

A loudspeaker voice-coil that moves through a magnetic field with velocity v will have an emf induced across the coil proportional to which quantity (for a single loop of length L in a uniform B)?

Which phenomenon causes some energy to be lost as heat when the voice-coil and magnet assembly moves rapidly inside a metallic structure?