Kirchhoff's voltage law problem: Batteries, switches, resistors

[kenok1216]

Homework Statement

for S1,S2,S3,S4 are all closed at the long time
find the current in each resistor

Homework Equations

The Attempt at a Solution

why I3 is not = i2?
the solution of this question is
24-28I₁-I₂12-12=0
7I₁-3₂=3-----(1)

12-12I₂-16₃=0
3I₂+4₃=3 ---(2)

I1+I2-I3=0---(3)

I1=0.492 I2=0.148 I3=0.639[/B]
why there are 3 current in 2loop and I2 is not =I3 and why at the top loop
the equation is not 24-28I₁-[I₁-I₂]12-12=0?

 

[andrewkirk]

why there are 3 current in 2loop

Currents are measured through wires, not in loops. There are three wires through which different currents are flowing (ignoring the wires with negligible resistance), so we measure three currents.

and I2 is not =I3

Because the currents going out rightwards from the top two wires return leftwards in the third wire.

 

[kenok1216]

Currents are measured through wires, not in loops. There are three wires through which different currents are flowing (ignoring the wires with negligible resistance), so we measure three currents.
Because the currents going out rightwards from the top two wires return leftwards in the third wire.

Thank