Electrical Watts

Electrical Watts – this web page provides a definition and explanation of the term ‘watt’.

What is a Watt?

A ‘watt’ is a unit of power – watts are the rate at which work is done.

Watts are used in many different fields of engineering but are most often used in an electrical context.

In electrical terms:

Power in Watts = voltage x current

Units of measurement: voltage = volts, current = amps,

If a machine uses a 20 volt power supply and draws 5 amps of current:

power in watts = voltage x current
power in watts = 20 x 5
power = 100 watts

‘in watts’ is usually left out of the equation to become:

power = voltage x current.

power = voltage x current
power = 20 x 5
power = 100 watts

If a machine uses a 100 volt power supply and draws 10 amps of current:

power = voltage x current
power = 100 x 10
power = 1000 watts

Wattage

It is common to refer to the power rating as ‘wattage’:

A 100 watt bulb – ‘the bulb wattage is 100 watts’.
A 60 watt bulb – ‘the bulb wattage is 60 watts’.

A bulb wattage rating is not a measure of the amount of light given off; the wattage is a measure of the electrical power a bulb consumes. The more power a bulb consumes the more light it gives off (the bulb is brighter). – Explanations Help Homepage