Gary Schafer wrote:
>>Average power is not a measure of heating ability. RMS power is a
>>measure of heating ability.
>>cr
>>
>>
>
>That's a common misconception.
>
I agree with you Gary (not specifically that its a common
misconception), but that RMS power is not the same as average power for
a sinusoidal voltage applies to a resistor.
For 1V peak voltage and 1 Ohm.
RMS power=sqrt(3/2)/2 W
mean power = 1/2. W
So they differ by a factor sqrt(3/2) or 1.2247.
>You can not find RMS power by multiplying RMS voltage by RMS current.
>That gives average power.
>
Yes, agree with you there too.
>If you square RMS voltage and divide by resistance that gives average power.
>
Yep, I agree there too.
>If you square RMS current and multiply by resistance that gives average
>power.
>
Yep, I agree on that one too.
I'd never really thought about RMS power, as it does not seem a
particulary useful thing, but if you work out the maths, it is indeed
not the same as average power for a sine wave voltage waveform.
I think for a square wave they would be the same, but not for a
sinusoidal voltage (and hence current) waveform.
--
Dr. David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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