Calculate the voltmeter reading for this circuit with 2 sources and 2 resistors

  • #1
songoku
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Homework Statement
Please see below
Relevant Equations
V = I.R
1685171477692.png


I find the current first, which is 2 A. Then the voltmeter reading would be 10 V - 1 x 2 = 8 V.

But the answer is 12 V.
I don't understand why it should be 10 + 1 x 2 = 12 V

Thanks
 
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  • #2
I agree with your answer. It obviously cannot be more than 10V.
 
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  • #3
Thank you very much haruspex
 
  • #4
Yes, I agree, 8V is correct.
 
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  • #5
Current returning to cell A = x
Current returning to cell B = y
Current entering the voltmeter = z

10- 1*x=0
4- 2*y = 0
z = y + x

X=10
Y=2
Z=12

U=RI

1/R=1/1+1/2
1/R=1,5
R=2/3

U = (2/3)*12 = 8

The reading is 8 Volts.
 
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  • #6
Welcome to PF, @erpelkon

erpelkon said:
Current returning to cell A = x
Current returning to cell B = y
Current entering the voltmeter = z

10- 1*x=0
4- 2*y = 0
z = y + x

X=10
Y=2
Z=12

U=RI

1/R=1/1+1/2
1/R=1,5
R=2/3

U = (2/3)*12 = 8

The reading is 8 Volts.
It is okay to offer alternate solutions to old schoolwork threads where the OP has already solved the problem. Please just keep in mind that in active threads, the OP must do the bulk of the work. We cannot offer solutions to them until after they have solved their schoolwork problem. Thanks. :smile:
 
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