What is a characteristic of carbon microphones?

Carbon microphones are characterized by their functioning mechanism, which involves varying resistance in response to sound waves. The microphone contains carbon granules where, when sound waves hit a diaphragm, they compress or expand these granules. This change in pressure alters the resistance of the carbon granules, effectively converting sound waves into an electrical signal.

This characteristic makes them similar to variable resistors, as the electrical resistance in the circuit changes with the input sound, allowing for the detection and transmission of audio signals. Unlike variable capacitors, which work based on changing capacitance rather than resistance, carbon microphones primarily rely on variations in resistance to operate. Furthermore, while carbon microphones can detect a wide range of sound frequencies, their fundamental principle does not restrict them to a particular frequency range or limit their application strictly to digital devices. They are primarily analog devices and have been widely used in various applications, including telephones and public address systems.