Introduction:
A capacitive microphone is a type of microphone that uses a capacitor to convert sound waves into an electrical signal. It is widely used in various applications, including telecommunications, audio recording, and public address systems.

Explanation:
A) Capacitive displacement transducer: A capacitive microphone is an application of a capacitive displacement transducer. A capacitive displacement transducer is a device that measures changes in capacitance to determine the displacement or position of an object. In the case of a capacitive microphone, the diaphragm acts as the object whose displacement is measured.

Working Principle of a Capacitive Microphone:
A capacitive microphone consists of a diaphragm, a backplate, and a spacer. When sound waves hit the diaphragm, it vibrates, causing a change in the distance between the diaphragm and the backplate. This change in distance alters the capacitance between the two plates. The capacitance is directly proportional to the distance between the plates.

Conversion of Sound Waves to Electrical Signal:
As the capacitance changes, an electrical signal is generated. When a voltage is applied across the plates, the changing capacitance causes a varying voltage. This varying voltage is then amplified and processed to produce an electrical signal that represents the sound waves.

Advantages of Capacitive Microphones:
1. High sensitivity: Capacitive microphones are highly sensitive and can capture even the slightest variations in sound.
2. Wide frequency response: They have a wide frequency response, making them suitable for recording various types of sounds.
3. Low noise: Capacitive microphones have low self-noise, resulting in clear and accurate sound reproduction.
4. Compact size: They are compact in size and can be easily integrated into different devices.

Conclusion:
A capacitive microphone is an application of a capacitive displacement transducer. It converts sound waves into an electrical signal by measuring changes in capacitance. Capacitive microphones have several advantages, including high sensitivity, wide frequency response, low noise, and compact size.