High
Intensity Discharge Lamps (HID.)
A
general group of lamps consisting of mercury, metal halide, high-pressure
sodium, and low pressure sodium lamps.
High-pressure Sodium Lamps
A
sodium vapor in which the partial pressure of the vapor during operation is
the order of 0.1 atmospheres.
Horsepower
The English unit of power, equal to work done at a rate
of 550 foot-pounds per second. Equal to 746 watts of electrical power.
Hot Cathode Lamp
An electrical
discharge lamp whose mode of operation is that of an arc discharge.
Hysteresis
A lagging of the magnetic flux in a
magnetic material behind the magnetizing force which is producing it.
