# 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 directly proportional to R whereas the second expression indicates inverse proportionality. How can the seemingly different dependence of P on R in these expressions be explained.

420 Points
13 years ago

You are not looking at other variables. Other variables are V and I. Suppose in a circuit there is a battery of V volt and resistance R. then I=V/R

P=I2R

put V=IR

P=V2/R

hence I and V are not constant here They are dependent on each other and they are relatad using R.

So you cant say P is directly or inversely proportional to R as other variables are not constant.

All the best.

AKASH GOYAL

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