What is an easy way to remember the rules in finding voltage, resistance and amps in parallel and series? eg: In series the value of current is same for all parts;in parallel the current is divided among the branches. How can I remember this and the other rules? What about voltage and resistance? What are the key things for me to remember to grasp this? I will have to do an analysis of DC circuits and analyze each one individually. The mix of parallel and series is confusing. Any ideas? I have been to a few sites but I still don't totally get it. Anyone else who can answer this without sending me to a website I don't understand, please answer.

I do understand Ohm's Law but I'm getting confused with the voltage drops and the differences in parallel and series.

It's getting worse! I'm trying to analyze a series-parallel circuit. The R1 and R2 are in parallel and those are in series with the R3. The combined resistance of R1,2 and 3 is in parallel with R4. The combined resistance of R1,2 3 and 4 is in series with R5. How do I simplify each circuit to determine my P and EIR?

Clare, dear. Off the top of my head, from which brain cells are flying at an alarming rate, I'll attempt this:

Combine R1 and R2 thus: Product over sum gives Rt of those two, Add that to R3 for total R of that leg of the combination. Now Repeat the product over the sum by taking that and R4 as the two quantities. The value you get for that can then be added to the value of R5. The same results would be obtained by adding the conductances for resistances in parallel. Thus: 1/R1 + 1/R2 = toatal conductance, the reciprocal of total conductance = total resistance. Remember that product over sum only applies when two parallel resistors are involved. For three or more use total conductance and invert for total resistance. Once you know the current total you would use Kirchoff's laws for voltage, I^2R for P, etc.

Thanks Frank.

More questions to come.

Clare, that's my great-granddaughter's name; Claire Frances Early; she's four years old going on twenty-four. I'm in the book if I can help, but I'm pretty old and decrepit and need a chalk board, so feel free to ask questions but don't expect too much "State of the Art". Here's a site that looks like it might be very helpful and thorough:Click on this for basic electricity instructions. E-mail me if I can help explain something.

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Originally posted by clarebear:
In series the value of current is same for all parts; in parallel the current is divided among the branches. How can I remember this...

Clare, take heart: it sounds like you've nailed the basic concept quite well! I can't improve on Frank's replies. Divide and conquer!

One old-fashioned concept that I haven't heard mentioned for years, that may prove helpful is the "hydraulic analogy". Think of the circuit as a bunch of pipes with water flowing through them. The generator or battery is the pump/tank source of pressure, the water is pumped through the network of pipe, where two pipes are parallel the water divides, more goes through the big pipe and less through the smaller (high resistance) pipe. The pressure (psi/volts)will be the same for each, but the gals. (gpm/amperes)will be in inverse proportion to the resistance; the total water/current coming out of the two pipes/resistors together will equal that going into the two. You can't have more or less current going out of a branch than is coming into it, whether that branch is the only one or a combination of several.

Frank and Professor,

Thank you both for your help and kind words. I finally figured it out! I got 100% on my test. Once I figure out that I could combine the parallel, I was fine. I figured out my ET of R1, R2 and R3 of the parallel and then added the series. I did this throughout the problem. It makes sense now.

I'm now working on sine waves. Fun.

Too cool, Clare! And for Frank (and Perf) who helped you get the ideas clear so you could get the answers! 100% ! That is so much up to you!