Question

the power of sound from the speaker of a radio is 20 Milli watt by turning the knob of the volume control the power of the sound is increased to 400 milliwatt .the power increase in decibles as compared to the original power is:
a. 13db
b. 10db
c. 20db
d. 800db​

Answer 1

Answer:A

Explanation:PαIL  

1 =10log  

10  (  I  0 I   )andL  

2 =10log  10  ( I  0 I  2  )

So, L  2 −L  

1  =10log 10  (  

I 1 I  2  )=10log  

10  (  P  1

​  

P 2  ) =10log  

10  (  

10

400

​  

)

=10log  

10

​  

20

=10log(2×10)

=10(0.301+1)

=13dB.

​  

 

Hence, the option A is the correct answer.