urgent help on these problems!

[phyznub]

1. The problem statement, all variables and given/known data

Questions 1:

http://g.imagehost.org/view/0961/DSC01830


Kirchoff's Rules problem on resistors...?

Four resistors are connected to a battery with a terminal voltage of 12 V, as shown below. Use Kirchoff's Rules to find the current in each branch of the circuit.




Question 2:


Physics Matrix problem involving circuits?


I have trouble with this problem.. So i have a ti-83 so, does that mean i put it into the matrix. But then what. How do i solve the problem. Could someone give me some steps and explaination on how to do so

Thanks!!

http://g.imagehost.org/view/0657/DSC01829


2. Relevant equations
I think there are the junction rule and loop rules. I1=I2+I3?
And use of calculator for matrix?


3. The attempt at a solution

1)So that would me loop and junction rule right?? how would i go about solving this problems, could someone show me the steps to do this?

2)I think I just need calculator help for this(ti-83) but what do they mean by solve it. SOlve what?

[Thaakisfox]

The first problem really cant be more straightforward...
You have two junctions and three loops, just write up the kirchoff laws.

For e.g. the loop rule for the lower loop will look like: 80\cdot I_2+30\cdot I_1 =12

The junction rule is self explanatory...

The second problem is basicaly a system of linear equations. You have to solve this system of equations, i.e. find I_1, I_2 etc.

Just write the respective coefficients of the unknowns, into a matrix, and use Gauss elimination.. you dont need a calculator, since this one is quite easy