# What is the SI unit of power?

###### Wiki User

###### 2010-10-23 01:30:43

The SI units for mechanical and electrical Power are the Watt

(W), and the Watt (electrical) (We) respectively.

**Power** is the rate of doing work, or at which energy is

converted. It can be thought of as - *"amount of energy used to*

*perform work, or converted from one form to another, in a specified*

*period of time, namely, in a second".*

The equation is P=W/t, where P is Power, W is the work done and

t is the time taken. The equation, P=E/t, where E is the amount

energy used to do the work, means the same thing. The unit for

Energy is the *Joule (J)*, and the unit for time is the

*second (s)*. The unit of power is then the **watt,**

*which is equal to 1 Joule (J) per second (s)*.

**Electrical Power**

There are a few different formulae depending on whether voltage,

current or resistance are being considered. Electrical power is

equal to the amount of current times the voltage, or P=IV.

Electrical power is also equal to the current squared times the

resistance, P=I2R

There are other formulae for the average electrical power of a

sinusoidal voltage, but this is beyond the scope of this

question.