# Voltage Divider Circuits - calculation error?

Discussion in 'Feedback and Suggestions' started by zordiac, Sep 29, 2008.

1. ### zordiac Thread Starter New Member

Sep 29, 2008
3
0
In the voltage divider circuits article, there appears to be an error; though, I am a novice, so perhaps I don't understand something?

Below this line in the article:
From here, we can use Ohm's Law (I=E/R) to determine the total current, which we know will be the same as each resistor current, currents being equal in all parts of a series circuit:

The chart shows 2m as the result of I; however, with other calculators I've used, I get 1m, not 2m. I'm unable to produce 2m no matter what I do. Can someone clarify or correct this issue?

Thanks very much.

2. ### jpanhalt Expert

Jan 18, 2008
7,394
1,709
Can you show your actual calculation? 45V/22.5k =2mA

John

3. ### zordiac Thread Starter New Member

Sep 29, 2008
3
0
I think I just don't understand how it works... I assumed you should divide the total voltage by the total resistance. From your example, it looks like you're just using the highest resistance in the circuit? Is this how it should be done?

Thanks.

4. ### jpanhalt Expert

Jan 18, 2008
7,394
1,709
22.5k is the total resistance, composed of 5 + 10 + 7.5. The column labeled "total" is not a single resistance, but is a calculation of the sum of the three actual resistors.

Can you draw and post something to show what you understand the circuit to be -- just to be sure we are talking about the same circuit? John

5. ### zordiac Thread Starter New Member

Sep 29, 2008
3
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John, we're talking about the same circuit. I think this is a result of staying up a little too late. I didn't register that the column was "total" for some reason; though it's plainly obvious now that I look again. Sorry about the misconception.

6. ### jessica Guest

This site is awesome i learned more in this one day, then 2 months in class. Thanks all.

7. ### Unregistered Guest

I don't understand why there are so many lets say, unhappy comments on this site. I understood the material very well. kVL law and voltage and voltage divider law. It was put very simple and sweet.

8. ### raybo Member

Oct 18, 2008
22
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Is insane to suggest that a potentiometer can be used to obtain lower voltages. well it can provided that the load remains the same and the load is considered in the design. He forget to mention some potentiometers are notlinear but a log function like volume controls. Otherwise reinventing ohms law. but well illustrated. rheostat?