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The electric power consumed by a device may be calculated by using either of the two expressions P=I^2R or p=V^2/R. The first expression indicates that it is directy proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly dependence of P and R in this expression be explained?

The electric power consumed by a device may be calculated by using either of the two expressions P=I^2R or p=V^2/R. The first expression indicates that it is directy proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly dependence of P and R in this expression be explained?

Grade:10

2 Answers

Sujit Kumar
111 Points
6 years ago
Look Resistance is a constant. You can't say something is directly or inversely proportional to a constant
In the equation
V = iR
V is proportional to i, and R (Resistance) is the constant
Similarly Power is directly proportional to the square of the current and inversely proportional to the square of the voltage.
Hope it's clear now
 
Mubashir ah
38 Points
6 years ago
In the first expression,P is directly proportional to R & in second it is inversely protional to R.But it must be noted that in first we take I as constant and in 2nd we take V as constant.

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