Question

uma lampada tem potencia de 60w quando ligada a 200 v. se for liagada a 110v a potencia sera ?

Answer 1

$\dfrac{U^2_o}{P_o}=\dfrac{U^2}{P}\\\\\\\dfrac{(200V)^2}{60W}=\dfrac{(110V)^2}{P}\\\\\\P=\dfrac{60W\cdot(110V)^2}{(200V)^2}\\\\\\P=\dfrac{60W\cdot12100V^2}{40000V^2}\\\\\\P=\dfrac{726000W}{40000}\\\\\\\boxed{P=18,15W}$

A nova potência será 18,15 watts.