Finding Voltage at D and Potential Difference Between B & E

AI Thread Summary
The voltage at point D is determined to be 3 V, but confusion arises as the expected answer is -3 V. The potential difference between points B and E is calculated to be 9 V by analyzing the changes in voltage as one moves through the circuit. A method to simplify the calculation without finding currents is suggested, focusing on the polarities of the batteries. The discussion emphasizes the importance of carefully tracing the voltage changes through the circuit. Ultimately, the correct approach to find the voltage at D is clarified through a step-by-step "walk" of the circuit.
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Homework Statement



What is the voltage at D ? What is the the potential difference between B and E?

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The Attempt at a Solution



The point D is connected to +6V and -3 V . So the effecting voltage at D is 3 V.
But the answer is -3 V.

For calculating the potential difference, I found out currents in all branches using KLR and JR.
Is there any shorter method without finding out the currents?
 

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Pay careful attention to the polarities of the batteries.

If you "walk" the loop from B to C to D to E, what's the change in potential?
 
From B to C, there is Vc - Vb = -3V and Ve-Vc=-6V (is it right?)
adding them Ve-Vb = -9V
so Vb-Ve = 9V

That answers my second question.
What about the first?
 
Abdul Quadeer said:
That answers my second question.
What about the first?

You passed by the answer when you "walked" from B to D! :smile:

"Walk" the loop from A to B to C to D.
 
I got it now.
Thanks!
 

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