1.

An electric bulb is rated 220 V and 100 W. When it is operated on 110 V, the power consumed will be : (a) 100 W (b) 75 W (c) 50 W (d) 25 W​

Answer»

:-Required power CONSUMED by the electric BULB is 25 W [Option.d] .Explanation :-We have :-→ Initial voltage (V) = 220 V→ Initial power (P) = 100 W→ NEW voltage (V') = 110 VTo find :-→ New power (P') .________________________________Firstly, let's calculate the resistance of the electric bulb .P = V²/R⇒ 100 = (220)²/R⇒ 100R = 48400⇒ R = 48400/100⇒ R = 484 ΩWe have got the resistance of the bulb . Now, we can calculate the new power consumed .P' = (V')²/R⇒ P' = (110)²/484⇒ P' = 12100/484⇒ P' = 25 W



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