Understanding Wheatstone Bridge Circuit: How to Solve for Unknown Voltages

AI Thread Summary
The discussion focuses on solving for unknown voltages in a Wheatstone Bridge circuit using Kirchhoff's laws. The user attempts to apply the laws but struggles with assumptions about voltage relationships, particularly whether Vbc equals Vdc. They derive equations based on current and voltage relationships but arrive at an incorrect final voltage of 0.94V instead of the expected value. Other participants clarify that the assumption of no current passing through BD is crucial and emphasize the importance of correctly applying Kirchhoff's laws to find the total current and measure voltage across points. The conversation highlights the need for careful analysis of voltage relationships in circuit problems.
needhelpperson
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How do i solve this? I wasn't given any examples at all. But I've tried to do this.

Iab + Iad = Ibc + Idc <--------- they have to or else Kirchoff's law violated.

so Vab = Vad but I'm not sure if Vbc = Vdc?
i'll continue assuming Vbc = Vdc

Vab/40 + Vad/20 = Vbc/70 + Vdc/50

Va=0.45714286 Vc

Vbd/60+ Vc/50 = Va/20

Vbd = 0.1714286Vc

i thought that Va + Vc + Vbd = 20

solved for Vc and i got Vbd as 2.105263 V

The answer is 0.94V. Obviously i got something wrong here. Can some one explain to me where I went wrong, and how i can fix this. Thanks
 

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I cannot download the attachment.Fix it pls
 
ColdRifle said:
I cannot download the attachment.Fix it pls

There's not anything he can do, since it's "pending approval"..
 
needhelpperson said:
Iab + Iad = Ibc + Idc <--------- they have to or else Kirchoff's law violetion

Tis is true only if at BD no current passes. moreover Vad=vdc and Vab=Vbc.
the special about that is that Iab=Ibc+Ibd and Iad=Idc+Idb. The one red is positive and the other negative...Since you find the total current that passes through bd you can measure the voltage across it :approve:
 

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