# Ohm's Law - Finding Source Voltage

• Brian82784
Brian82784
TL;DR Summary: Ohms Law Source Voltage DC series Circuit

Hello,

I'm trying to figure out how to determine source voltage of a DC series circuit. The only information given is

Resistor 1 = 12ohm
Resistor 2 = 9ohm
Resistor 3 = 3ohm

And the voltage drop across R1 is 6V.

The answer is 12V for the DC battery. But I can't figure out how to get to 12.

If I put 12V down as the battery size, and combine all three resistors 24ohm and use ohms law I can't come up with 12V.

R total = 24ohm
12V source battery

24 divided by 12 = 2Amps

Now if I go to R1 and knowing that the circuit amperage is 2, I get a voltage drop of 2A * 12ohm = 24V not 6V.

Where am I going wrong?

Brian82784 said:
24 divided by 12 = 2Amps
Reminder: V=IR

Gavran
Brian82784 said:
And the voltage drop across R1 is 6V.
So this gives you the current through R1, and hence that same current flows through all 3 series resistors.

Brian82784 said:
Resistor 1 = 12ohm

And the voltage drop across R1 is 6V.
So what is the current?

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