# Power output

1. Feb 21, 2010

### jdoggigs

1. The problem statement, all variables and given/known data
A 580w heater is designed for use in Germany, where electric outlets supply 230V(rms) service. What is the power output of the heater when plugged into a 120V(rms) outlet in the U.S.? Ignore the effects of temperature on the heater's resistance.

2. Relevant equations

barP=I(rms)V(rms)

3. The attempt at a solution
I tried to fine I(rms) by first calculating for I in germany: I(rms)=(580w)/(230V).
Then I used this I(rms) to calaulate U.S. power output; barP=(I(rms))(120V).
This did not give the correct answer.
Would I have to consider that germany uses DC and U.S. uses AC, is there a conversion for this?
Thanks
jdoggigs

2. Feb 21, 2010

### Redbelly98

Staff Emeritus
Welcome to Physics Forums.

Irms will be different in the US than it is in Germany. However, one out of the 4 usual variables will be the same. Question for you: which one?

(The 4 usual variables are V, I, R, and P.)

3. Feb 21, 2010

### kbaumen

Btw, Germany does use AC. No country (as far as I know) uses DC as mains.

4. Feb 22, 2010

### jdoggigs

Irms is what I need to find th US power outout, I have no resistance, P is the answer I'm
looking for, so voltage is the same. I'm lost here how does this help?
I assumed that Europe used DC because You need different plugs there.

5. Feb 22, 2010

### jdoggigs

Okay after some consideration of the question asked, I figured it out.
Thanks for all the help'