# Power and heaters

#### 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!

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#### Redbelly98

Staff Emeritus
Homework Helper
R=(230^2)/2000
Not quite. At 230 V, the power will be different than 2000 W.

A heater rated at 2000W operating at 250V ...
So, P is 2000W when V=?

#### jakey

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

So, P is 2000W when V=?
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

#### Redbelly98

Staff Emeritus
Homework Helper
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
Yes, correct up to this point.

and the answer I would subtract from 2000W? is it right? thanks
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.

#### jakey

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

"Power and heaters"

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