An electric bulb has a rating of 500 W, 100 V. It is used in a circuit having a 200 V supply. What resistance must be connected in series with the bulb so that it deliver 500 W ?
(a) 10 Ω
(b) 20 Ω
(c) 30 Ω
(d) 40 Ω
Correct option (b) 20 Ω
Explanation:
If we connect a 20 Ω resistance in the series , the p.d. across the bulb will be 10 volt so power consumed will be 500 watt
