Derive the expression for power P consumed by a device having resistance R and potential difference V. A derive of resistance R is connected across a source of V voltage and draws a current I. Derive an expression for power in terms for voltage for current and resistance.

Derive the expression for power P consumed by a device having resistan

1.	Derive the expression for power P consumed by a device having resistance R and potential difference V. A derive of resistance R is connected across a source of V voltage and draws a current I. Derive an expression for power in terms for voltage for current and resistance.
Answer» SOLUTION :Amount of work done in carrying a charge Q through a POTENTIAL difference V is W=QV But `Q=It therefore W=Vit` As power is DEFINED as the rate of doing work, hence Power `P=W/t=(Vit)/t=VI` IF R be the value of resistance of the conductor , then V=RI and hence `P=VI=(RI)=I^2R` Again `P=VI=V.(V/R)=V^2/R` Thus, in general we can say that electric power is given by `P=VI=I^2R=V^2/R`