Microphones (ht Only) (GCSE Physics)

Which statement about shielding and magnetic interference for dynamic microphones is correct?

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?

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

A dynamic microphone converts mechanical power from sound into electrical power. Which statement about energy conversion is correct?

Why is Lenz’s law important to understand when designing a microphone’s suspension and restoring forces?

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?

A moving-coil microphone is tested with a signal generator driving a small mechanical shaker that produces uniform diaphragm velocity across a range. The measured induced emf is linear with diaphragm velocity but drops at low frequencies. What is the most likely explanation for the low-frequency drop?

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)?

Which factor most directly increases the induced emf in a microphone for a given diaphragm displacement amplitude?

Which property of the magnet in a moving-coil microphone most directly affects the sensitivity (voltage per unit diaphragm displacement)?

In Faraday’s law emf = -N dF/dt, if a microphone’s coil has N turns and the diaphragm causes the flux through each turn to change sinusoidally with time at fixed amplitude, how does induced emf scale with N?