Wheatstone Bridge circuit [Archive]

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needhelpperson

Nov13-04, 11:37 AM

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

ColdRifle

Nov14-04, 07:41 AM

I cannot download the attachment.Fix it pls

Nylex

Nov14-04, 08:04 AM

I cannot download the attachment.Fix it pls

There's not anything he can do, since it's "pending approval"..

ColdRifle

Nov15-04, 04:31 AM

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: