Illumination : Study of light

 Luminous flux: 

The measure of the amount of light coming out of a light source.    S.I unit -> Lumen.

Luminous intensity:

The Intensity of light per unit solid angle in a particular direction.    S.I unit -> Candela

Laws of Illumination-

• Illumination at a point is directly proportional to the luminous intensity of the light source.
• Illuminance at a point is inversely proportional to the squared distance between the light source and the point.
• It is directly proportional to the cosine of the angle between the perpendicular and the line joining the point of consideration and the light source.