Light consists of electromagnetic waves
Luminous efficiency of a fluorescent tube is 60 lumen/watt. Luminous efficiency is the ratio of luminous flux output to input power. Its unit is Lumen/Watt.
Candela is the unit of Luminous intensity. Luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle. The SI unit of luminous intensity is Luminous flux per unit solid angle or Lumen per Steradian or Candela.
Both (a) and (b)
Illumination of one lumen per sq. meter is called Lux. One lux is equal to one lumen per square metre.
A solid angle is expressed in terms of Steradians.
The unit of luminous flux is Lumen.
Incandescent lamps (Filament lamps) operate normally at a power factor of Unity.
The filament of a GLS lamp is made of Tungsten.
Fine diameter tungsten wires are made by Wire drawing.
10 to 15 percent
10 to 15 percent of the input energy is radiated by filament lamps.
GLS lamps is the cheapest for the same wattage.
60 ? 65 lumens/watt
Lambert?s cosine law
The colour of sodium vapour discharge lamp is Yellow.
Carbon Arc lamps are commonly used in Cinema projectors.
All above factors
All of the above factors
3.5 percent loss in the light output