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an electric bulb is rated 220V and 100W .When it is operated on 110V ,the power consumed will be?

Shruti Yadav , 10 Years ago
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KAPIL MANDAL

Last Activity: 10 Years ago

At first, you have to understand why bulb glows. It is because heat produced there due to resistance. 
The voltage V is related to power P by the formula,
P = I * V
I is the current through the resistance where the voltage is applied. Again,
V=IR.
So, P= V2 / R
Or,  R= V2/P 
Here, R = 2202 /100 = 484 ohms.
Putting this back in the eqn P= V2 / R, with V=  110, 
P= 1102/ 484 = 25 watts. 
 
 

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