Power dissipation calculation across resistor from FM equation

Q.  Calculate the dissipation in power across 20Ω resistor for the FM signal
v(t)= 20 cos(6600t+ 10sin2100t)
- Published on 14 Oct 15

a. 5W
b. 20W
c. 10W
d. 400W

ANSWER: 5W
 
A standard FM signal is represented by
v(t) = Ac cos(2πfct + kfsin2πfmt)
Ac = carrier amplitude
fc = carrier frequency
kf = modulation index
fm = modulating frequency
kf = frequency deviation/modulating frequency
the power dissipated across 20Ω resistor is given by
Vrms2/R
=(20/√2)2/R
= 5W

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    Discussion

  • umakanta bhatta   -Posted on 02 Jul 17
    sir ans will be 10. correct the calculation

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