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The problem for theoretical current was:
List the resistnace of each resistor solve for the theoretical current and voltage drop for each resistor in the circuit. There was a circucit that was parallel. The resistances were the following: R1-55 R2-18 R3-10 R4-75 R5-100 R6-15 R7-22 . how would you then calculate the theoretical current and voltage drop???

I'm assuming every resistor was connected in parallel?

In that case I'm assuming they gave you the total voltage? In that case it's really easy. You know voltage in parallel always is the same, so just apply Ohm's Law to each individual resistor to find the current.

If you want to find total current, add the current of each resistor together (Kirchoff's Current Law) or find the total resistance (using the formula for resistance in parallel) and apply Ohm's Law.

If a component in a circuit was rated at 1 watt, would that mean that it uses 1 joule in 1 hour?

The values of the resistors that are given to you are nominal. All resistors have a tolerance. For example, the R5=100 ohms may have a 5% tolerance. That means the actual resistance measured may be as low as 95 ohms and as high as 105 ohms. The "theoretical" current and voltage drop across this resistor is calculated with the nominal value of 100 ohms. When you put a meter across the resistor the readings you take won't exactly match the "theoretical" current or voltage you calculated because of this tolerance. Furthermore, batteries put out more voltage than they are listed at. A fresh 1.5 volt battery puts out 1.6 volts, a 6 volt battery puts out 6.4 volts, a 9 volt battery puts out 9.6 volts, and a 12 volt battery puts out 12.8 volts. Again the "theoretical" calculation will use the nominal voltage of the battery and actual readings will not match.

1 watt = 1 joule/second
1 watt-hour= 1 joule/second * 3600 seconds/hour = 3600 joules
normally expressed in Kilowatt-hours
1 KW-hour = 1000 joules/sec * 3600 seconds = 3.6 x 10^6 joules

Thank you.

I was researching batteries, and I found plenty about wet cells, but is a dry cell basically just the same thing as a wet cell except that the electrolyte is in a paste? And since lemon juice is apparently an electrolyte (is there a specific reason why?) that's why when you stick two terminals of different metals (do the types of metals matter?) into a lemon you get voltage, correct?

And on my reference sheet, I have a resistor color code chart, formulas, and diagrams of a DC motor, a wet cell, and magnetism around a conducting wire. Is there anything I'm forgetting?

K, on soinc.org, there's the training handout. All it is, is questions, like in a test form. It doesn't actually give you information. Anywhere where we can find the answers??

EDIT: Nevermind, it's in the power point. Sorry.

blue cobra wrote:Thank you.

I was researching batteries, and I found plenty about wet cells, but is a dry cell basically just the same thing as a wet cell except that the electrolyte is in a paste? And since lemon juice is apparently an electrolyte (is there a specific reason why?) that's why when you stick two terminals of different metals (do the types of metals matter?) into a lemon you get voltage, correct?

And on my reference sheet, I have a resistor color code chart, formulas, and diagrams of a DC motor, a wet cell, and magnetism around a conducting wire. Is there anything I'm forgetting?

1)Yes, a dry cell is basically the same thing as a wet cell. Ideally, though, wet cells are better because of easier current-flow conditions. (Basically.)

2)Acids and electrolytes are almost completely "interchangeable" as scientific terms, because they both contain free ions. When a chemical is described as an acid, it is being noted that it has a composition that will attempt to dissolve objects placed within it. When a chemical is described as an electrolyte, it is being noted that it will conduct electricity. They are terms that have specific uses, but generally will describe the same objects. (did that make sense?)

3)When you are doing such a "lemon-battery" experiment you just described, it is best to select metals with high conductivity. However, the most power you'll get out of this experiment is perhaps .1 Volts. (So, yeah, a lemon will generate electricity.)

4)I put some stuff about inductance, because that's the only section about electricity that I have trouble with...but it depends on whether those notes are enough for you.

Edit: You may want to list some tools used when measuring electricity, and how they are used/how they function.

I've been to Invitationals at Pembroke Hill, and the test there was mostly composed of fill-in-the blank questions that word basic concepts in a strange way (i.e. "What creates electrical energy?" (might not be exact wording), the answer was "The separation of charges". Uh... what?)

So, my question is, should I be studying more about basic concepts, or should I be laerning about the superpositioning theorem?

...definitely basic concepts first.

I think I need more practice analyzing circuits. I thoroughly understand Ohm's law, but under the pressure of competition with kilo's and milli's thrown at me, I'm much less than accurate. Are there any good sites that have practice problems like that?