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problem in simple resistor circuit

1 vote

Find the potential difference between point M and N.

I tried to do it by considering 0 potential at a point and taking out potential at other points wrt it and was able to solve it.

I want to solve this with kirchoff laws if so then how ?
I have not applied kirchoff law to circuits with many batteries and how shall I take out potential difference.

asked Mar 26, 2017 in Physics Problems by physicsapproval (2,290 points)
edited Mar 26, 2017 by physicsapproval
Is the answer is 2V
yes , but I want to solve it using kirchoff laws
Sorry the answer should be 7V
No answer is 2V
You apply Kirchhoff's Laws just the same  in circuits with few or many elements. You have not shown your attempt to do so.
I don't get how to apply KVL across the connecting wire .
how shall I distribute the current  I am unable to establish KCL
The current should not flow through connecting wire .
If there is no loop (circuit) there is no loop current. In the steady state, current only flows in circuits (loops).
Okay, So  A and B would be at potential difference of 4V .

1 Answer

0 votes

No current flows through the connection AB. Current flows in loops, and there is no other route by which the current could return to A. In order to sustain a current in wire AB there would have to be a source of electric charge at A and a sink to absorb electric charge at B.

The 4V cell maintains a potential difference of 4V between B and A, with A being more +ve.

In the loop at A, the 1V source is divided equally between the 5$\Omega$ resistors, so that M is 0.5V higher than A.

In the loop at B, the 3V source is divided in proportion between 3, 2 and 1$\Omega$ resistors, so there is a 0.5V drop across the 1$\Omega$ resistor. The potential of point N is -3+0.5 = -2.5V below that at point B.

So M is 2.5+4.0+0.5 = 7.0V above N.

answered May 11, 2018 by sammy gerbil (26,678 points)