Microphones (ht Only) (GCSE Physics)

A moving-coil microphone’s output leads must be connected to the preamplifier with correct polarity. If one mic sounds thin when added in parallel with another and cancels at some frequencies, what is the likely cause?

Which measurement would directly indicate the sensitivity (volts per pascal) of a dynamic microphone?

In a studio, two moving-coil microphones capture the same source and are summed. If one microphone has a much higher self-noise level, what is the effect on the combined signal-to-noise ratio (SNR)?

If you double the speed at which the coil cuts magnetic flux (for example, due to a louder sound producing larger diaphragm velocity), what happens to the instantaneous induced emf (ignoring nonlinearities)?

A moving-coil microphone is placed near the pole face of the magnet with the coil axis perpendicular to the field. For maximum induced emf the coil should:

When using a dynamic microphone as a pickup for a musical instrument string (e.g., acoustic guitar), why is placement crucial?

Why might a microphone’s output be inverted (180° phase shift) compared with a loudspeaker input, and why does phase matter in multi-mic setups?

A microphone’s output cable picks up a time-varying magnetic field from a nearby loudspeaker transformer, producing hum. Which engineering solution targets the problem most directly?

In a moving-coil (dynamic) microphone the sound causes the coil to move in a magnetic field and an electrical signal is produced by electromagnetic induction. Which equation gives the instantaneous emf induced across a straight wire of length l moving at speed v at right angles to a magnetic field of strength B?

Faraday’s law for a coil of N turns links induced emf to the magnetic flux F through the coil. Which is the correct form of Faraday’s law?

In a microphone, why is it important that the coil moves freely with minimal mechanical damping (apart from intended electrical damping)?