What is power (electricity)?

Power is a form of measurement used in electrical systems that denotes the rate per unit of time at which electricity is transferred through an electrical system.

Key Takeaways:

  • Power is the rate at which electricity is transferred through a system.
  • Power is measured in watts.
  • One watt equals one joule per second.

Understanding Power

Electric power is, essentially, a measurement of an electrical system to describe the rate at which electricity is transferred through an electrical system and typically measured in watts (1 watt = 1 joule per second). Sometimes the term wattage is colloquially used on its own to reference “electric power in watts”.

Power is generated by devices such as steam, solar, or wind generators that convert energy into electrical power. This power is then transmitted from the point of generation to the point of consumption by way of transmission lines.

From the standpoint of electric power, components in an electric circuit can be divided into two categories:

Passive devices (loads) which ‘consume’ electric power from the grid and convert it to other forms of energy such as mechanical work, heat, light, etc. Examples are electrical appliances, such as light bulbs, electric motors, and electric heaters. 

Active devices (power sources) which convert other types of energy such as mechanical or chemical energy into electrical power for future use. Examples of this type of device include electric power generators and batteries.

Related Terms

Rated Power – Rated power is the power output of a device under its ideal operating conditions.

Solar Energy – Electrical energy generated by the sun and harnessed for use by solar panels.

Power Density – Power density refers to the total amount of power per unit of volume that a device holds.