# Average power and diodes.

1. Apr 12, 2008

### Icetray

[SOLVED] Average power and diodes.

Hi,

I have this question. If a diode were connected to a circuit with an alternating current and there was a resistor was connected to it, will the average power change? For example, if we take the following values,

V max = 6.0 V
Resistance = 100 ohms,

the Average power will be 0.18 W and the max power 0.36W. When we plot the graph with respect to power dissipated by the resistor with a diode connected, we get a sinusoidal graph with it's second half cycle at a null value and it's first half at a peak value of 3.6W (assuming that the diode is forward biased at the start).

I'm not very sure how to calculate max power using graphs; but is the average power still 0.18W?

2. Apr 12, 2008

### Icetray

Anyway, I think I solved it. Thanking the Half Rectified wave to be H and the original unrectified full wave to be F, the mean power of the half rectified wave should be half that of the full wave.

Therefore,

<$$P_{H}$$> = 1/2<$$P_{F}$$>
= 1/2($$P_{o}$$/2)
= 1/4 $$P_{o}$$

where $$P_{o}$$ is the max power.

Last edited: Apr 12, 2008