Kirchoff's Voltage Rule

[MedPR]

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From EK.

Kirchoff's second rule states that the voltage around any path in a circuit must sum to zero. If we imagine voltage as the height difference between two points, this rule states the obvious that the height of the starting piont does not change when we go around some path (regardless of the path) and end up back where we started.

This makes absolutely no sense to me. Help please!

 

[SaintJude]

Don't take this a cop-out, but I highly recommend you watch a video on Kirchoff's rule. Circuits are best explained/understood visually or in person. It's so easy once you see it.

 

[MedPR]

Any suggestions on which vid to watch? I'm sure there are thousands out there on the internet.

 

[milski]

Don't forget that the source is included an counts in the opposite direction. All the rule is saying is that when you make a full loop and arrive at the same point in the circuit, the difference between the two voltages is zero. Anything else would imply that you could go around the circuit, return to where you started and have a different potential. In other words, you'll have two potentials at the same spot - something that makes no sense.

In a lot of sense, the rule is similar to saying that if you start from a place in the mountain, wonder around for awhile and come back to the same place, your change in potential energy will be zero.

 

[SaintJude]

Any suggestions on which vid to watch? I'm sure there are thousands out there on the internet.

I'm hesistant to make suggestions, because different learning styles may warrant different teaching approaches.

But this videos seems promising/highly rated:

http://www.youtube.com/watch?v=2Risrvhatbg

& His Simple Example has good responses
http://www.youtube.com/watch?v=KImEKebwudo&feature=related

 

[MedPR]

Don't forget that the source is included an counts in the opposite direction. All the rule is saying is that when you make a full loop and arrive at the same point in the circuit, the difference between the two voltages is zero. Anything else would imply that you could go around the circuit, return to where you started and have a different potential. In other words, you'll have two potentials at the same spot - something that makes no sense.

In a lot of sense, the rule is similar to saying that if you start from a place in the mountain, wonder around for awhile and come back to the same place, your change in potential energy will be zero.

Ok, but if your battery puts out 6 volts, and all 6 volts come back to the opposite side of the battery, you have a short-circuit. Every picture I've seen - TBR, Nova, EK - shows the returning voltage to be 0. If you put out 6, and return with 0, how is that "when you make a full loop and arrive at the same point in the circuit, the difference between the two voltages is zero"?

 

[milski]

Ok, but if your battery puts out 6 volts, and all 6 volts come back to the opposite side of the battery, you have a short-circuit. Every picture I've seen - TBR, Nova, EK - shows the returning voltage to be 0. If you put out 6, and return with 0, how is that "when you make a full loop and arrive at the same point in the circuit, the difference between the two voltages is zero"?

That is correct but you have to remember to include the batter itself in the circuit. So you start at 0 at one end of the battery, go across it up to 6, then go through any resistors or whatever in the circuit which lower the voltage and by the time you come back to the battery you're back at 0.

 

[MedPR]

That is correct but you have to remember to include the batter itself in the circuit. So you start at 0 at one end of the battery, go across it up to 6, then go through any resistors or whatever in the circuit which lower the voltage and by the time you come back to the battery you're back at 0.

Oh, duh.

The voltage is 0 at the anode, and 6 at the cathode = 6volts leaves the battery, but 0 volts must re-enter at the anode.

Thank you 🙂