Match List I with List II
| LIST I | LIST II | ||
|---|---|---|---|
| A. | Modulation | I. | Retrieval of information from the carrier wave at the receiver |
| B. | Baseband signals | II. | Frequency range over which an equipment operates |
| C. | Demodulation | III. | Superimposition of a signal on a high frequency wave |
| D. | Bandwidth | IV. | Band of frequencies representing the original signal |
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → A-III, B-IV, C-I, D-II
In a communication system the message (baseband) signal is too low in frequency to be sent directly, so it is carried by a high-frequency wave and recovered at the receiver.
(A) Modulation — this matches (III) Superimposition of a signal on a high frequency wave. The information is impressed on the carrier by varying its amplitude, frequency or phase.
(B) Baseband signals — this matches (IV) Band of frequencies representing the original signal. This is the range of frequencies of the original message signal itself.
(C) Demodulation — this matches (I) Retrieval of information from the carrier wave at the receiver. It is the reverse of modulation.
(D) Bandwidth — this matches (II) Frequency range over which an equipment operates. For example, the bandwidth of a channel is the range of frequencies it can handle.
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 – “… (ix) Bandwidth: Bandwidth refers to the frequency range over which an equipment operates or the portion of the spectrum occupied by the signal. (x) Modulation: … 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. … (xi) Demodulation: The process of retrieval of information from the carrier wave at the receiver is termed demodulation.”
Modulation and its Necessity – “… Message signals are also called baseband signals, which essentially designate the band of frequencies representing the original signal, as delivered by the source of information.”