Electrical networks(linear algebra)

[EV33]

Homework Statement

Determine the currents in the various branches.

Then there is a picture of the network which has batteries, resistors, and nodes.

Most of the problems have the currents labeled.

My question is when the currents are not labled how do you determine where to put them and what direction to give them?

Homework Equations

No equations.

The Attempt at a Solution

By looking at the the various electrical networks in the book it looks like you can put the currents anywhere and in any diretion.

 

[HallsofIvy]

Without the picture, this question makes no sense at all! In any case, it looks like a physics problem to me. The whole point is to find the currents using such physics laws as the drop in voltage over a resistor and "conservation of charge".

I'm going to move this to physics homework.

 

[kerimek]

Is this correct?

I would approach this problem by utilizing the principles of Kirchhoff's laws and Ohm's law. Kirchhoff's laws state that the sum of currents entering a node must equal the sum of currents leaving the node, and the sum of voltage drops in a closed loop must equal the sum of voltage sources in that loop. Ohm's law states that the current through a conductor is directly proportional to the voltage and inversely proportional to the resistance.

First, I would identify all the nodes and apply Kirchhoff's current law to each one. This would give me a system of equations that I can solve to determine the currents in each branch.

To determine the direction of the currents, I would use Ohm's law and the given voltage sources to calculate the voltage drops across each resistor. The direction of the current would be in the direction of the voltage drop.

If the problem does not provide any voltage sources, I would assume a direction for each current and solve the system of equations. If the calculated currents are negative, then I would know that the assumed direction was incorrect and I would have to reverse it. I would repeat this process until I get a consistent set of positive currents.

In summary, to determine the currents in a network, one must apply Kirchhoff's laws and use Ohm's law to find the direction of the currents. It is important to have a consistent direction for each current in order to get accurate results.