In the detection of amplitude modulated wave, the carrier frequency is usually changed to a long frequency by:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → IF stage
In a typical AM receiver, the received signal is first amplified, and then the IF (intermediate frequency) stage changes the carrier frequency to a lower, fixed intermediate frequency before the signal reaches the detector. Working at one fixed, lower frequency makes the later amplification and detection easier.
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):
Detection of Amplitude Modulated Wave – “… In addition, to facilitate further processing, the carrier frequency is usually changed to a lower frequency by what is called an intermediate frequency (IF) stage preceding the detection.”