Theoretical electronics problem

[aranud]

Homework Statement

I have made a picture af a circuit that you can see in the attachment.
My teacher told me that at the points (A,C) and (B,D) the voltage (potential) is equal.
Because of that there won't be a current between A and C and B and D (Ohm's formule)
However, he has made an extra connection between A and D and now he asks us to find, for a given resistance of that connection, the current going through that connection.
The voltage between A and D is also given.
Also the two connections between + and - have a different resistance.
I would be very grateful if someone would be able to clear this up for me.
My whole class is unsure about the problem and although i don't really need the grades, i would still like to know answer out of pure interest in it.

Homework Equations

U/R=A
parallel connection: 1/R1+1/R2+...=1/Rn
serial connection: R1+R2+...=Rn

The Attempt at a Solution

Because there is difference in voltage (potential) between A and D, there should also be a current between A and D. However there are two different ways to get from A to -.
Via B or going via D. So the current should split up because it is a parallel connection.
But because i don't know the resistance between A and B ( i do know the resistance between A and D) i can't calculate the current through A and B.
Example problem :
resistivity: 49E-8
length: 25 m
A = 2E-6
difference in voltage between A and D ( potential) 10 Volt

 

[aranud]

I already managed to figure it out on myself so no help is needed anymore.
If anyone is interested: the current is divided over the two connections but because your resistance is known, and your voltage as well you immediately find the current through it.
It was actually the easiest question in the whole book! I still aced the test though :)

 

[thomate1]

The first step in solving this theoretical electronics problem would be to redraw the circuit with the new connection between A and D. This will help visualize the circuit and make it easier to analyze.

Next, we can apply Kirchhoff's laws to the circuit. Kirchhoff's current law states that the sum of currents entering a node must equal the sum of currents leaving the node. In this case, the node at A has two currents leaving it, one going to B and the other going to D. The current entering the node at A must equal the sum of these two currents.

Using Ohm's law, we can calculate the current through each resistor in the circuit. The current through the resistors between + and - will be equal, as they are in parallel. The current through the resistor between A and B can be calculated using the given resistance and the voltage between A and D.

Once we have calculated the currents through each resistor, we can use Kirchhoff's voltage law to determine the voltage at point D. This law states that the sum of voltage drops in a closed loop must equal the sum of voltage rises. In this case, the voltage drop across the resistor between A and D will be equal to the voltage rise across the resistors between + and -.

Now that we have determined the voltage at point D, we can use Ohm's law again to calculate the current through the resistor between A and D. This will be the same current that is going through the resistor between A and B.

In summary, to solve this theoretical electronics problem, we need to use Kirchhoff's laws and Ohm's law to calculate the currents and voltages in the circuit. The key is to properly apply Kirchhoff's laws and keep track of the different currents and voltages in the circuit.