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A message signal of frequency 20 KHz and peak voltage of 20 volts is used to modulate a carrier signal of frequency 2 MHz and peak voltage of 40 volts. Determine (i) modulation index, (ii) the side bands produced. Draw the corredponding frequency spectrum of amplitude modulated signal.

(i) modulation index =  Am/ Ac=20/40=0.5

    The side bands are (2000+20) KHz

                          =2020 KHz and (2000-20)KHz

                          = 12980 KHz                                           (1/2 +1/2) mark

 Amplitude versus w for amplitude modulated signal: page number 525 NCERT part (ii) Figure 15.9, Ac=40 volts, μAc/2=10 volts   (1) marks

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