a. The input to an amplifier is 30 W. The output is 100 W. What is the gain?

b. A cable has an input 4 W and an output 1 W. What is the loss?

c. The output of a cable is measured to be 24 mW. The cable loss is –8 dB. What is the input power?

Question

a. The input to an amplifier is 30 W. The output is 100 W. What is the gain?

b. A cable has an input 4 W and an output 1 W. What is the loss?

c. The output of a cable is measured to be 24 mW. The cable loss is –8 dB. What is the input power?

Accepted Answer

a. From Formula (25-12),[latex]dB=10\log \frac{P_o}{P_i}[/latex]

[latex]dB=10\log \frac{100}{30}=10(0.523)[/latex]

=5.23

b. From Formula (25-12),[latex]dB=10\log \frac{P_o}{P_i}[/latex]

[latex]dB=10\log \frac{1}{4}=10(0.602)[/latex]

=-6.02

c. From Formula (25-13),[latex]\frac{P_o}{P_i} =\log ^{-1}\frac{dB}{10}[/latex]

[latex]P_o/P_i=\log ^{-1}(-8/10)=6.3[/latex]

[latex]24/P_i = 6.3[/latex]

[latex]P_i = 24(6.3) = 151.4 [/latex]

Question 25.2: a. The input to an amplifier is 30 W. The output is 100 W. W...