Watt W
About the Watt
One watt is one joule per second. The unit honours James Watt, whose steam-engine work also gave rise to the horsepower, about 745.7 W. Light bulbs, engines and power stations are all rated in multiples of the watt.
Related Units
Mechanical horsepower
hp550 ft·lbf/s ≈ 745.7 W
James Watt defined horsepower to market his steam engines against draught horses, settling on 33,000 foot-pounds per...
Hertz
Hz1 Hz = 1 s⁻¹
The hertz is one cycle or event per second and replaced the older expression cycles per second. It is named after...
Radian
rad1 rad = 1 m/m (dimensionless); 180°/π
A radian is the angle subtended at the centre of a circle by an arc equal in length to the radius, so a full turn is 2π...
Steradian
sr1 sr = 1 m²/m² (dimensionless)
The steradian is the solid angle that cuts out an area equal to the square of the radius on the surface of a sphere. A...