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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 the power is directly proportional to R, whereas the second expression indicates inverse proportionally. How can the seemingly different dependence of P or R in these expression be explained ?

Text Solution

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`P = I^(2)R` is used when current flowing in every component of the circuit is constant. This is the case of series combination of the devices in the circuit.
`P = v^(2)//R` is used when potential difference (V) across every component of the circuit is constant. This expression is used in case of parallel combination in the circuit. In series combination ,R is greater than the value of R in parallel combination.
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