Verified Solution • 2025–26 Session moderate

QJEEM23Ph6908: JEE Main 2023 Physics - Class 12 JEEM23Ph6908 Solution: The amplitude of is modulated by signal. The amplitude…

The amplitude of 15sin⁡(1000πt)15 \sin (1000 \pi \mathrm{t}) is modulated by 10sin⁡(4πt)10 \sin (4 \pi \mathrm{t}) signal. The amplitude modulated signal contains frequencies of

A. 500 Hz500 \mathrm{~Hz}

B. 2 Hz2 \mathrm{~Hz}

C. 250 Hz250 \mathrm{~Hz}

D. 498 Hz498 \mathrm{~Hz}

E. 502 Hz502 \mathrm{~Hz}

Choose the correct answer from the options given below:

Multiple Choice Options

  • A A and C only
  • B A and B only
  • C A and D only
  • D A, D and E only

Step-by-Step Verified Solution

When an amplitude modulated signal is created, the frequency components of the resulting signal consist of the carrier frequency, the sum, and the difference of the carrier and modulating frequencies.

In this case, the carrier signal is 15sin⁡(1000πt)15 \sin (1000 \pi t) , which has a frequency of

1000π2π=500Hz\frac{1000 \pi}{2 \pi} = 500 \mathrm{Hz} (Option A).

The modulating signal is 10sin⁡(4πt)10 \sin (4 \pi t) , which has a frequency of 4π2π=2Hz\frac{4 \pi}{2 \pi} = 2 \mathrm{Hz} .

Now, we find the sum and difference of the carrier and modulating frequencies:

Sum: 500Hz+2Hz=502Hz500 \mathrm{Hz} + 2 \mathrm{Hz} = 502 \mathrm{Hz} (Option E)

Difference: 500Hz−2Hz=498Hz500 \mathrm{Hz} - 2 \mathrm{Hz} = 498 \mathrm{Hz} (Option D)

So, the amplitude modulated signal contains frequencies of 500 Hz, 2 Hz, 498 Hz, and 502 Hz.

The correct answer is (A, D, and E only).

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