Which of the following is a transducer?(A) Loudspeaker(B) Amplifier(C…

The correct answer is Option (4) → (A) and (D) only

A transducer is a device that converts energy (or a signal) from one form into another, for example sound into an electrical signal or an electrical signal into sound.

(A) Loudspeaker — Correct. It changes an electrical signal into sound, so it converts electrical energy into sound energy.

(B) Amplifier — Incorrect. It makes a weak electrical signal stronger. The signal is electrical at the input and electrical at the output, so no change of form takes place.

(C) Rectifier — Incorrect. It changes alternating current into direct current. Both the input and the output are electrical, so it is not a transducer.

(D) Microphone — Correct. It changes sound into an electrical signal, so it converts sound energy into electrical energy.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), and it also appears to be out of the CUET 2026 syllabus.

NCERT (Pre-rationalised edition, 2022-23):
Basic Terminology Used in Electronic Communication Systems – “… (i) Transducer: Any device that converts one form of energy into another can be termed as a transducer.”