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Passive sign convention

Integrator741

Jun 16, 2013
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Hi.

So I am doing a bit of revision exercises, and I need to check with someone that I understood something.
Please see the picture attached.

Using passive sign convection topic, from uni lectures, I answered the question. Can somebody please have a quick look, and tell me if am right?

Thank you.
 

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Ratch

Mar 10, 2013
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Hi.

So I am doing a bit of revision exercises, and I need to check with someone that I understood something.
Please see the picture attached.

Using passive sign convection topic, from uni lectures, I answered the question. Can somebody please have a quick look, and tell me if am right?

Thank you.
I would think it would be 10 watts supplying, 50 watts supplying, 40 watts absorbing, 20 watts absorbing. Power generated is 60 watts, Power absorbed is 60 watts,

Ratch
 

Bluejets

Oct 5, 2014
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If one were to look upon the 40v as say a battery and the other 2 sources driving the 1A then power would be 60W.........(no?)
 

Sunnysky

Jul 15, 2016
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There is no doubt the total power transferred is 60W.
But by convention P= + for load and - for supply.

The voltage sources with current flowing in (+) convention regardless if a generator, battery or PSU appear as a load, however batteries undercharged, may store energy as this load, generators turn into motors as PSU's have to deal with reverse currents in some manner.

minor detail but important.
 

Ratch

Mar 10, 2013
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If one were to look upon the 40v as say a battery and the other 2 sources driving the 1A then power would be 60W.........(no?)
Battery or whatever else, the 40 volt source is absorbing energy.
 

hevans1944

Hop - AC8NS
Jun 21, 2012
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Looks good to me.
Except the OP got Question 2 wrong. The answer is 60 watts, as @Ratch said in post #4 and @Sunnysky implied in post #3.

Battery or whatever else, the 40 volt source is absorbing energy.
As is the 1A current "source" which is absorbing 20 watts, adding to the 40 watts absorbed by the 40 volt "source" to yield 60 watts total absorbed power from the 50 volt and 10 volt "sources".

If the OP (or anyone else) is still confused, take two aspirins and go read (and re-read) the Wikipedia article first linked by @Sunnysky in post #3.
 

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