Finding where my Kirchhoff's law circuit calculation went wrong

[needhelpperson]

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

 

[AVNguyen]

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

Your problem is you continue to asume that Vbc=Vdc, that lead you to the wrong answer.
First, you should find the current for the whole circuits, you can divide the circuits into parts .Then you can find the pottential of each part, then you can find the current of each resistance, then you subtract them to find the dirrection of the current through Rbd. Be careful at the last part.

 

[wais]

It seems like you have correctly applied Kirchoff's law to the circuit, but there may be some issues with your calculations. Here are some steps you can follow to solve the circuit problem:

1. Start by drawing the circuit diagram and labeling all the known values, such as the resistors and voltage sources.

2. Apply Kirchoff's voltage law to each closed loop in the circuit. This means that the sum of all voltage drops in a closed loop must equal the sum of all voltage sources in that loop.

3. Apply Kirchoff's current law at each junction in the circuit. This means that the sum of all currents entering a junction must equal the sum of all currents leaving that junction.

4. Use Ohm's law (V=IR) to calculate the voltage drops across each resistor.

5. Use the equations from steps 2 and 3 to create a system of equations. This will help you solve for the unknown voltages and currents in the circuit.

6. Solve the system of equations to find the values of Vab, Vad, Vbc, Vdc, and Vbd.

7. Double-check your calculations and make sure they are consistent with the given values and Kirchoff's laws.

If you are still having trouble, it may be helpful to consult with a classmate or your instructor for clarification. It's also important to carefully check your calculations and make sure you are using the correct units. Good luck with your circuit problem!