# NCERT Physics Class 12 Exemplar Ch 15 Communication Systems Part 5 (For CBSE, ICSE, IAS, NET, NRA 2022)

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Q 28 An amplitude modulated wave is as shown in Fig. Calculate

(i) The percentage modulation,

(ii) Peak carrier voltage and,

(iii) Peak value of information voltage. An Amplitude Modulated Wave is as Shown in Fig

Ans:

From the figure

1. Percentage modulation

1. Peak carrier voltage
2. Peak information voltage =

Q 29 (i) Draw the plot of amplitude versus ‘ω’ for an amplitude modulated wave whose carrier wave is carrying two modulating signals, and

[Hint: Follow derivation from Eq 6 of NCERT Textbook of XII]

(ii) Is the plot symmetrical about ? Comment especially about plot in region .

(iii) Extrapolate and predict the problems one can expect if more waves are to be modulated.

(iv) Suggest solutions to the above problem. In the process can one understand another advantage of modulation in terms of bandwidth?

Ans: