Consider the following statements about the microphone and the speaker of a mobile phone: 1. The microphone converts sound to a mechanical signal. 2. The microphone converts sound to an electrical signal. 3. The speaker converts a mechanical signal to sound. 4. The speaker converts an electrical signal to sound. Which of the statements given above are correct?

A microphone and a speaker are both electroacoustic transducers that convert energy between acoustic and electrical forms. A microphone functions as an acoustic-to-electric transducer, capturing sound waves (pressure variations) and converting them into electrical signals. This process often involves a diaphragm that vibrates in response to sound, inducing an electrical current. Conversely, a speaker (or loudspeaker) acts as an electric-to-acoustic transducer. It receives electrical signals from an amplifier and converts them back into sound waves. While the internal mechanism of a speaker involves converting electrical energy into mechanical movement of a diaphragm to push air, the primary functional conversion for the device as a whole is from an electrical signal to sound. Therefore, statements 2 and 4 are correct, while statements 1 and 3 are incorrect as they misidentify the output/input signals.