Which of the following best describes how wireless telephones are able to receive and produce sound from one person to another?

A.

Electromagnetic waves are received and then vibrate a speaker which produces additional electromagnetic waves.

B.

Sound waves are received and then vibrate a speaker which produces electromagnetic waves.

C.

Sound waves are received and then vibrate a speaker which produces additional sound waves.

D.

Electromagnetic waves are received and then vibrate a speaker which produces sound waves.

D.

Electromagnetic waves are received and then vibrate a speaker which produces sound waves.

Explanation:

The telephone has a receiver-transducer component that can receive electromagnetic wave - radio waves spectrum - and transform them into electric energy. This electric energy is then transformed into sound energy by a speaker. This is how we're able to listen to a phone call.

The opposite happens when we speak on the phone. The sound energy is transformed into electric energy by a microphone - the reverse of a speaker. The transducer now changes the electric energy into electromagnetic waves that travel through space to the recipient in the phone conversation.