Definition:Power (Physics)

This page is about power in the context of physics. For other uses, see power.

Definition

Power is defined as the amount of energy transferred or converted per unit time.

That is, the rate at which energy is transformed.

Power is a scalar quantity.

Instantaneous

The instantaneous power transformed at an instant of time is defined as:

$\map p t = \dfrac {\d \map E t} {\d t}$

where:

$\map p t$ is the power as a function of time

$\map E t$ is the energy as a function of time.

Symbol

The usual symbols used to denote power are $P$ or $p$.

Dimension

The dimension of measurement of power is $\mathsf {M L}^2 \mathsf T^{-3}$.

This derives from its definition as:

$\dfrac {\text{Energy} } {\text {Time} }$

Unit

The SI unit of power is the watt $\mathrm W$.

Also see

• Results about power in the context of physics can be found here.

Sources

• 1969: J.C. Anderson, D.M. Hum, B.G. Neal and J.H. Whitelaw: Data and Formulae for Engineering Students (2nd ed.) ... (previous) ... (next): $1.$ Units and Abbreviations: $1.2$ SI units $(2)$ Derived units
• 1976: Ralph J. Smith: Circuits, Devices and Systems (3rd ed.) ... (previous) ... (next): Chapter $1$: Electrical Quantities: Definitions and Laws: Definitions: Table $1$-$2$: Important Derived Quantities
• 1976: Ralph J. Smith: Circuits, Devices and Systems (3rd ed.) ... (previous) ... (next): Chapter $1$: Electrical Quantities: Definitions and Laws: Definitions: Power
• 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): power: 4.
• 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): power: 4.