# Instantaneous power

A sinusoidal voltage source v =10V sin(ωt) is connected across a 1k resistor.

1. Make a sketch of p(t), the instantaneous power supplied by the source.
2. Determine the average power supplied by the source.
3. Now, suppose that a square wave generator is used as the source. If the square wave signal has a peak-to-peak of 20 V and a zero average value, determine the average power supplied by the source.
4. Next, if the square wave signal has a peak-to-peak of 20 V and a 10 V average value, determine the average power supplied by the source.

This image has the picture of my partial solution:

• Can you mark up $t_1$ and $T$ on your graph so we know what you're talking about. The image quality is not good. See if you can improve the contrast. – Transistor Apr 14 at 13:39
• @Transistor The image contains my solution to the average power (2), kindly help with the others. – Ademola Apr 14 at 16:43
• Draw the voltage and power graphs for Q3 and things should get quite clear for that question. Post a (better) photo into your question. – Transistor Apr 14 at 17:08
• @Transistor I've been trying to upload my new solution but it fails – Ademola Apr 14 at 18:19

Your answer to part 2 is correct (although I didn't check all of the intermediate steps). The plot of instantaneous power is a sine wave that has a minimum of zero and a maximum of $$\\frac{{10 V}^2}{1000 \Omega} = 0.1 W\$$. The average value of this waveform is half the peak, or 0.05 W.