Vitamin A Capsule On Face

the light intensity is defined as the amount of luminous flux emitted by a source per unit solid angle . Its unit of measurement in the International System of Units is candela (cd), which is a fundamental unit of the system. Mathematically, the expression is:

In photometry, is called point source to one that emits the same light intensity in all directions considered. A practical example would be a lamp. On the contrary, it is called source or reflective surface of Lambert to one in which the intensity varies with the cosine of the angle between the direction considered and the normal to the surface