What is a high pressure mercury Vapour lamp?
High-pressure mercury gas-discharge lamp; High-pressure mercury-vapor lamp. Definition. Lamp that produces light as a result of an electrical discharge, generated between two electrodes, in a high-pressure mercury vapor that is contained in a transparent bulb.
Why is the mercury Vapour at low pressure?
The initial high voltage burst is necessary to produce electrons with enough kinetic eergy to ionise the mercury atoms – the atoms in the gas need to be sparse enough (low pressure) so that KE can be built up to a level that will allow ionisation of the mercury atoms.
What is the difference between sodium Vapour lamp and mercury Vapour lamp?
Answer: The light in Sodium Vapour lamp is from an atomic emission process whereas in Mercury Vapour Lamp it is, finally, from fluorescence emission. The mechanism of light emission in a sodium vapour lamp is simple and straight-forward.
How much power does a mercury vapor light use?
Compared with newer HID lighting, mercury vapor isn’t very energy efficient. The “efficacy”—or amount of light produced per unit of electricity consumed—is 20-60 lumens per watt. This is better than incandescent lamps (about 15-20 lumens per watt), but significantly lower than other HID lighting.
Is Mercury Vapour lamp monochromatic?
Filaments of the lamp sputter fast moving electrons, which hit the sodium atoms (vapour) causing the valence electrons of the sodium atoms to excite to higher energy levels and the electrons thus excited relax by emitting the characteristic monochromatic bright yellow light (589nm).
How many types of mercury Vapour lamps are there?
The bulbs have an inner quartz tube containing the mercury vapor discharge. This is enclosed by an outer glass bulb that filters out harmful short-wavelength ultraviolet (UV) radiation. There are two types of mercury vapor light bulbs sold in the U.S.
What is a multi vapor lamp?
Metal halide or multi vapor lamps are a form of the light source that creates light via passing an electric arc through a gaseous mixture of mercury vapor and vapor of some metal halides.