I know this is very simple task but I'm new to this so I just need someone to tell me if i solved it correctly. My english is not very good so I will use only P for power, R for resistance, I for current and U for voltage. The task is: In electric network that has voltage 220V, power of the device falls down from 1000W to 800W because of overload. I need to calculate fall of the voltage. The resistance stays constant. So i took $ P=R*I^2 $ and $I=\frac{U}{R} $ then $P=R*\frac{U^2}{R^2}$ i.e. $P=\frac{U^2}{R}$ If i calculate R i get $R=48.4 \Omega$. If I put that in second equation where $P=800W$ i get $U=196.7V$ so fall of the voltage would be $\Delta U =23.3V $ . I just need to know if this is correct. I am pretty new to this and there are no solutions in book so i need to check. Thank you.
Tell me more
×
Physics Stack Exchange is a question and answer site for
active researchers, academics and students of physics. It's 100% free, no registration required.
|
closed as too localized by David Zaslavsky♦ May 31 '12 at 6:50
This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, see the FAQ.
