The process of superimposing message signal with the carrier wave is known as:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → modulation
A low-frequency message signal cannot be sent far by itself, so it is carried by a high-frequency carrier wave. Superimposing the message on the carrier, so that a property of the carrier (amplitude, frequency or phase) varies with the message, is called modulation.
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 – “… (x) Modulation: The original low frequency message/information signal cannot be transmitted to long distances because of reasons given in Section 15.7. Therefore, at the transmitter, information contained in the low frequency message signal is superimposed on a high frequency wave, which acts as a carrier of the information. This process is known as modulation. As will be explained later, there are several types of modulation, abbreviated as AM, FM and PM.”