# Voltage Drop Of DC Resistors

Discuss Voltage Drop Of DC Resistors in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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#### SparkSmog

Welcome to ElectriciansForums.net - The American Electrical Advice Forum

Im currently doing a electrical course at college and im stupidly stuck on the most simple question. Due to my teacher not being the most approachable i thought id ask here for help, heres the question; http://img205.imageshack.us/my.php?image=71997536ox1.jpg

Im asked to calculate the amps and the voltag drop of the circuit, am i right in thinking that the sum of all voltage drops is equal to the voltage applied to the circuit (V1+V2+V3 would equal 12volts)?

Any help is appreciated as ive done all my kirchoffs law and the effects of capacitors etc but the simplest one has completely confused me

Thanks

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#### mrloy99

##### -
Im currently doing a electrical course at college and im stupidly stuck on the most simple question. Due to my teacher not being the most approachable i thought id ask here for help, heres the question; http://img205.imageshack.us/my.php?image=71997536ox1.jpg

Im asked to calculate the amps and the voltag drop of the circuit, am i right in thinking that the sum of all voltage drops is equal to the voltage applied to the circuit (V1+V2+V3 would equal 12volts)?

Any help is appreciated as ive done all my kirchoffs law and the effects of capacitors etc but the simplest one has completely confused me

Thanks
can't click on to your link and i'm fuk'd if I'm gonna type all that in.

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#### SparkSmog I understand that firstly you calculate I1 which is 12v/(15ohm+20ohm+10ohm)
v1 is then calculated by I1 x R1

V2 is then calculated by I1 x (20ohm+10ohm)????

I2 is then calculated by V2/R2??

I start to get myself a touch confused and start double guessing myself now....

Ignore this post - Im an idiot Thinking about th simplest of questions far too much

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#### Guest123

Thank God for that, I thought it was me. #### mrloy99

##### - I understand that firstly you calculate I1 which is 12v/(15ohm+20ohm+10ohm)
v1 is then calculated by I1 x R1

V2 is then calculated by I1 x (20ohm+10ohm)????

I2 is then calculated by V2/R2??

I start to get myself a touch confused and start double guessing myself now....

Ignore this post - Im an idiot Thinking about th simplest of questions far too much[/quote

I'll give you a clue.....Your current is the same throughout D

#### DanBrown

Very simple question this guys!.. Lol - we all know its been a long time but come on..

To start with find find the total resistance. (R1 + R2 + R3) = 45 ohms
To find the circuit current (I1)
I1 = V/R = 12v / 45 ohms = 0.26A or 260mA
Once we have calculated the I1, we automatically know I2 and I3 because the current is the same throughout the circuit.
No we have got our current value, we need to find the voltage drop across each resister.
V1 = I x R = 0.26A x 15 ohms = 3.9V
V2 = I x R = 0.26A x 20 ohms = 5.2V
V3 = I x R = 0.26A x 10 ohms = 2.6V

The volt drop across each resistor, will all add upto the supply voltage (12v) or near enough...

Hope this helps.. Reply to Voltage Drop Of DC Resistors in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net