- #1
dauto said:Don't waste time trying to guess the direction of the currents. Just chose one that seems reasonable. If you make a mistake somewhere, it is a self correcting mistake because the solution for those currents that were chosen in the wrong direction will turn out to be negative numbers indicating that the current is in the opposite direction.
baby_1 said:Dear Jhenrique
for writeing KVL equation at first you should define the direction of current or voltage of each element.it depends on you how you can assume the element voltage or current sign or direction.for example i set the voltage sign in this form
now for first loop we write KVL
-V1+V2+V5-V3=0
and for third loop we have
-V7-V4+V5=0
above equations were an example of setting voltage signs.after set the voltage sing and write KVL equation you should solve them.i assume that we find V5=2 and V3=-1 so the circuit could be same as this
or combine the sign of voltage that specified and the sign of voltage that you obtain. redraw the circuit like this
Jhenrique said:Ok... so why the my equations in the 1st post are wrong?
dauto said:I said don't waste time guessing the direction of the currents. Just chose one. Your 1st post is wrong because you didn't chose a direction
Jhenrique said:I found another way more easy of solve it (my ideia isn't solve the problem, is understand the dynamical of the electrical circuit)
if I apply the hydraulic analogy like this video:
and the superpostion theorem:
http://en.wikipedia.org/wiki/Superposition_theorem
together with KVL
##\oint \vec{E} \cdot d\vec{s} = 0##
in this case:
and choose a mesh and a sense of circulation, so the "ramps" (source or resistor) would have positive voltage and the declivities correspond to negative voltage!
dauto said:Yes, that's the way to solve the problem. Guess what you will get out of it. Yes, you get Kirchhoffs' laws. No kidding...
The 2nd Kirchhoff's Law, also known as Kirchhoff's Voltage Law (KVL), states that the sum of all voltages in a closed loop in an electrical circuit is equal to zero.
To apply the 2nd Kirchhoff's Law in electrical circuits, you need to identify all the voltage sources and resistors in the circuit. Then, using KVL, you can write an equation by summing up all the voltage drops and setting it equal to zero. This equation can be solved to find the unknown voltages or currents in the circuit.
Yes, the 2nd Kirchhoff's Law can be applied in any type of circuit, whether it is a series, parallel, or a combination of both. It can also be applied in more complex circuits with multiple loops.
No, the 2nd Kirchhoff's Law is not necessary in every circuit analysis. It is only necessary when the circuit includes multiple loops or when the unknown quantities cannot be determined using other circuit analysis methods.
Yes, the 2nd Kirchhoff's Law can be used in both DC and AC circuits. However, in AC circuits, the voltage sources and resistors are represented by complex numbers, and the sum of voltages in a closed loop is equal to the complex conjugate of zero.