# How to find the total power delivered in this circuit?

#### Withering

Joined Mar 25, 2018
8
Hello, I'm trying to find the total power delivered in this circuit (see attached image). I'm new to circuit theory; but, from my understanding...

The 40 V source delivers power; so, power will be negative for this element.

The 9 V element absorbs power. Power will be positive for this element.

The 48 V element absorbs power. Power will be positive for this element.

The 5 A source delivers power. Power will be negative for this element.

I don't know how to get the voltage across the 5 A source. I think I only need to calculate the power for the 5 A & 40 V sources in order to get the power delivered in the circuit.

Help is appreciated!

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Joined Mar 10, 2018
4,057
P = V x I
V = Sum of all voltages in series (observing polarities) , I you know.

Regards, Dana.

Joined Mar 10, 2018
4,057
I stand corrected orchardaudio, thanks for the lesson.

But then I think thevinin equivalent of V is algebraic sum of
all V sources, which is 17V x 5A = 85W.

orchardaudio, did you take down your post ?

Regards, Dana.

Last edited:

#### Withering

Joined Mar 25, 2018
8
Hello, that isn't the total power delivered to the circuit.

I ended up working this problem out & getting the correct answer.

Joined Mar 10, 2018
4,057
I am thinking physics definition of work (a scalar quantity) implies its the sum
of work being delivered by each element, so its

P = 48 x 5 + 9 x 5 + 40 x 5 + ( 48 + 9 - 40 ) x 5
= 240 + 45 + 200 + 85
= 570

Regards, Dana.

#### Dodgydave

Joined Jun 22, 2012
9,075
57V x 5A = 285W