In a brownout the power company's voltage drops. Assuming the voltage drop is small, how would I figure out how much of a voltage drop it takes for a 60W light bulb to act like a 50W bulb? The relevant equation I am guessing would be P=V^2/R. I also know the resistance doesn't change. I tried P=(V-h)^2/R for small h, representing the power in a small voltage drop. thus P is approximately V-2Vh/R but I don't think this helps me any since I haven't eliminated h. What do you think?