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CBSE - XII Science - Physics - Current Electricity

A bulb is rated 120V.But it is to be connected to a mains supply of 80V.How does the current flow and brightness change?

Asked by Swarnalakshmi Murugan 2nd August 2012, 6:27 PM
Answered by Expert


In the given case,
rated voltage, V1= 120V
applied Voltage, V2= 80V
Let current in the rated case be: I1
and in second case: I2
Since resistance of the bulb be R.
I1 = 120/R
I2 = 80/R
thus I1/I2 = 3/2
and since power is dirctly proportional to I2
P1/P2 = 9/4
Answered by Expert 3rd August 2012, 7:24 PM

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