And that's = 0.

So that's our second equation we get from Kirchhoff's Voltage Law for loop two.

And now we have a third loop that we want to look at.

Our third loop is down here at the lower right hand corner of our circuit.

And if we look at that, the voltage drop again starting in the lower left hand

corner, we have a 2 ohm register that we can find the voltage drop for.

Then we encounter the dependent source and we don't know what the voltage drop is for

this dependent current source.

Again, we could find the voltage drop for the 3 ohm resistor as we did in the last

equation and for the 1 ohm resistor as well.

But we have a problem in that we have this voltage source, or

this current source in this loop.

So we really can't write an equation that sums these voltages up,

unless we want to introduce another unknown variable,

the voltage drop across this dependent source.

So in order to avoid that we use the concept of a super mesh and

we can define a super mesh around this circuit that allows

us to sum up the equation, sum up the voltages around another loop.

And so if we try to do that we can try to do perhaps a loop around the outer

portion, then coming down the center part of our circuit.

But we can't do that because we again encounter this 15A source.