What should be the value of the ressistor?

Science & Mathematics by Anonymous 2018-06-29 13:32:59

Social Science

3 answers

A bulb of 500w and 100v is to be connected in series with a ressistor so that the power of the bulb stays the same. The circuit supplies 200v. What is the value of the ressistor??

Anonymous

R = V^2/W Since V of bulb = V of R and they are connected in series, then R of bulb must = resistor value Resistor value = [(200 - 100)V^2]/(500W) = 20 Ohms (but it must also be a 500 Watt resistor)
Anonymous

The resistor must be the voltage drop, 200-100=100v @ 500/100= 5 A. So you need a 100 / 5 = 20 ohms 5*20=100 W resistor. 20Ω @ 100W resistor. https://www.mouser.com/ProductDetail/Ohm...
Anonymous

What current is drawn by a 500w bulb at 100v? I = P/V = 5A What resistor drops (200-100) volts when passing 5A? 100/5 ohms = 20 ohms <<<