Dissipation of Power by Resistors

1. Mar 16, 2009

cwesto

1. The problem statement, all variables and given/known data

2. Relevant equations

P=IV
I=V/R
P=(V/R)V
R=V2/R

3. The attempt at a solution

PR1: 122/12=12
PR2: 144/18

I'm not sure what to do from here. Thanks for any input and help!

2. Mar 16, 2009

LowlyPion

Your attempt incorrectly tried to use the total Voltage of the supply across the resistors singly. The question wants to know the power dissipated by each resistor.

Once you have the current then won't the power for any resistor be P = I2R ?

3. Mar 16, 2009

cwesto

I=V/R
Rtotal=12+18
I=12/30
PR1=RI2
PR1=12*$$\frac{2}{5}$$*$$\frac{2}{5}$$
PR1=48/25

PR2=$$\frac{72}{25}$$=2.88
Thanks!

4. Mar 16, 2009

LowlyPion

There you go. Good job.