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The electric power consumed by a device ...

The electric power consumed by a device may be calculated by using either of the two expressions : `P = I^2 R` 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 ?

Text Solution

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`P=I^2R` is used to calculate electric power when the current flowing through the circuit is constant (Series combination).
`P = V^2//R` is used to calculate electric power when the potential difference flowing through the circuit is constant (Parallel combination).
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