Correct Answer - Option 1 : Luminous flux
Explanation:
Luminous flux: It is defined as the energy in the form of light waves radiated per second from a luminous body. It is represented by the symbol ‘ϕ’ and measured in lumens.
Lumen: It is defined as the luminous flux emitted by a source of one candle power per unit solid angle in all directions.
Lumen = candle power of source × solid angle
Lumen = CP × ω
Total flux emitted by a source of one candle power is 4π lumens
llumination: It is defined as the luminous flux received by the surface per unit area. It is usually denoted by the symbol E and is measured in lux or lumen/m2 or meter candle or foot candle.
Illumination = (luminous flux/area) lux
The unit of illumination is lux.
Luminous intensity (Luminance) in a given direction is defined as the luminous flux emitted by the source per unit solid angle.
