Question

an electric bulb rated for 500 watts at 100 volts is used in a circuit having a 200 volt supply. the resistance that must be put in series with the bulb so that bulb draws 500 watts is

Answer 1

If the bulb has a nominal power 500 W, we can calculate the resistance of this bulb:
P=(V×V)/R
where P is the nominal power, W; V is the nominal voltage, V; R is the resistance of the bulb, Ω.
R=(100×100)/500=20Ω
current I=V/R=100/20=5amp
Then, total resistance at 200 V should correspond to the nominal current:200/5=40Ω
As you know, total resistance of resistors in series is equal to the sum of their individual resistances:40Ω-20Ω=20 Ω


Answer: 20 Ω.

Answer 2

${\huge{\blue{\boxed{\boxed{\pink{\underline{\underline{\mathfrak{\red{ ♡ANSWER ♡  }}}}}}}}}}$

HOPE IT HELPS YOU