# Amplifier power dissipation excercise

#### andrew74

Joined Jul 25, 2022
55
Hi! I am having some difficulty solving this excercise:

An amplifier operates with a single 15V supply, delivers a peak-to-peak amplitude sinusoidal signal of 12V to a 1k load, and absorbs negligible current from the signal generator. The continuous current supplied by the 15V supply is 8mA.
What is the power dissipated in the amplifier and its efficiency?

(results: 102mW and 15%)

In the resolution pictured below I have assumed zero input power, because I have no data on it in the text

I solved it by recalculating using $V_{RMS}$

Last edited:

#### MrAl

Joined Jun 17, 2014
9,558
Hi! I am having some difficulty solving this excercise:

An amplifier operates with a single 15V supply, delivers a peak-to-peak amplitude sinusoidal signal of 12V to a 1k load, and absorbs negligible current from the signal generator. The continuous current supplied by the 15V supply is 8mA.
What is the power dissipated in the amplifier and its efficiency?

(results: 102mW and 15%)

In the resolution pictured below I have assumed zero input power, because I have no data on it in the textView attachment 272415

I solved it by recalculating using $V_{RMS}$

Hello,

Is your entire post showing up?

To calculate AC power you have to convert peak to RMS. Do you know how to do that with a sine wave?
Your power result for the output is incorrect so far.

#### andrew74

Joined Jul 25, 2022
55
Hello,

Is your entire post showing up?

To calculate AC power you have to convert peak to RMS. Do you know how to do that with a sine wave?
Your power result for the output is incorrect so far.
Yes, I was able to arrive at the result by using the RMS value in the calculations.
Thank you!

#### MrAl

Joined Jun 17, 2014
9,558
Yes, I was able to arrive at the result by using the RMS value in the calculations.
Thank you!
Hi,

Oh well i mentioned that because in your post it does not look like you did that it looks like you used the peak voltage.