# physics: Electricity/Resistance

posted by charlie

If I have a 9V circuit, with:

2 resistors in parallel; followed by:
2 single resistors in series;

and I calculate the effective R of the parallel pair (using 1/R=1/R1+1/R2); can i then add this value to the series resistors to get a total for the circuit? As in:

(1/R=1/R1+1/R2)+R3+R4 = Reff

If so, can I now use Ohm's Law to get the current flowing through the last single resistor?

Thanks

1. bobpursley

The way you did it in the formula, you added the reciprocal of the parallel resistance to R3 and R4.

Rparallel= (R1*R2/(R1+R2))
then add that to R3 and R4

2. charlie

I get it. My text shows your formula, but recommends 1/R= 1/R1+1/R2 etc as easier! I'm with you. If the numbers match, is my thinking ok?

3. charlie

I forgot to say "take the reciprocal". Does that make more sense?

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