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An audio signal of frequency 500 Hz and voltage 2.4 V is frequency modulated with a carrier wave, and a frequency deviation of 4.8 kHz occurs.If the audio voltage is increased to 5 V, the frequency deviation (in kHz)  will be : 

Option: 1

10


Option: 2

9.6


Option: 3

4.8


Option: 4

5


Answers (1)

best_answer

As we have learned

Value of frequency deviation (d) -

\delta = f-f_{c}
 

- wherein

d_{max}= f_{max}-f_{c}

= \pm KE_{m}

E_{m}= modulating  amplitude

 

 We know for frequency modulation , frequency devaition \delta \propto E_m

\delta= K E_m

Here 4.8 KHz = K(2.4 V)

K = 2 KHz / V

Now the audio voltage is incresed to 5V since the deviation is proportional to audio voltage , it shall also increase accordingly 

      \delta _{new}= K E_m | _{new }

= (2 KHz / V)  * 5V 

      \delta _{new}= 10KHz

 

 

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chirag

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