Q.The output transducer of the communication system converts the radio signal into ----------------

Step 1. The output transducer is the very last block in the receiver chain (Elements of a Communication System, item 9). It takes the amplified, demodulated baseband electrical signal and converts it back into the original physical form of the information.

Step 2. The most familiar output transducer, the loudspeaker, is specifically designed to reconvert an electrical signal into sound -- the original information the system was built to carry (speech or music).

Step 3. Eliminating the other options: (b) Mechanical energy and (c) Kinetic energy are generic physics terms, not the specific information form (sound) that a communication receiver's output transducer is built to restore; (d) is wrong since a definite correct answer (a) exists.

Identify the output transducer's job: restore the electrical signal to the original information form (sound, for a typical voice/audio link).

• Confusing the output transducer's function with the receiving antenna's (which converts EM waves to an RF electrical signal, not to sound).
• Picking a generic energy term like 'kinetic energy' instead of naming the actual information form the system restores.