Power and heaters

1. Mar 2, 2009

jakey

1. The problem statement, all variables and given/known data
A heater rated at 2000W operating at 250V is used on a supple of 230V. if the resistance of the heater will not be affected by temp, what is the power absorbed by the heater?

2. Relevant equations
i think that the only equation to use will be P=V^2/R

3. The attempt at a solution
because the resistance of the heater is its internal property, i would first compute for the resistance from: R=(230^2)/2000. afterwhich, i would compute the power absorbed by the heater through: V=250-230=20 -> P = (20^2)/R which will be computed from the previous equation. is this right?

thanks!

2. Mar 2, 2009

Redbelly98

Staff Emeritus
Not quite. At 230 V, the power will be different than 2000 W.

So, P is 2000W when V=?

3. Mar 2, 2009

jakey

oh sorry. so, i think it shouldve been R=V^2/P and V=250V while P=2000W.

so, the power when it operates at 230V is simply P= 230^2/R and the answer I would subtract from 2000W? is it right? thanks

4. Mar 2, 2009

Redbelly98

Staff Emeritus
Yes, correct up to this point.

Uh, no. The problem statement asks for the power when V=230V. So just use the power you get from
P= 230^2/R​
... and that's the final answer.

5. Mar 2, 2009

jakey

lol, i misinterpreted the question. thanks, really!!!:D

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