technical question, plz answer with explanation
Ques. An electric bulb is rated 220V and 100W.Wen it is operated on 110V,the power consumed will be? i)100W ii)75W iii)50W iv)25W
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Your Answer
Answer is option 4
Explaination:
Power
P=I*V
where I is the current, V is the voltage
But ohms law says:
I=V/R
where R is the resistance
so:
P=V^2/R
so we know that when operated at 220 volts, the power is 100w, so we can work out the resistance:
R=220^2/100
R= 484 ohms.
Now when operated at 110 volts:
P=V^2/R
=110^2/484
=25 Watts
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Ashly
- 14 Mar
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