Law of Inverse squares:

Illumination at a point is inversely proportional to square of its distance from the point source and directly proportional to the luminous intensity (CP) of the source of light in that direction.

• If a source of light which EMITS light equally in all DIRECTIONS be placed at the centre of a hollow sphere, the light will fall UNIFORMLY on the inner SURFACE of the sphere. 
• If the sphere be replaced by one of the larger radius, the same total amount of light is spread over a larger area proportional to the square of the radius.

Lambert’s COSINE law:

The illumination at a point on a surface is proportional to cosine of the angle which ray makes with the normal to the normal to the surface at that point.

Law of Inverse squares:

Illumination at a point is inversely proportional to square of its distance from the point source and directly proportional to the luminous intensity (CP) of the source of light in that direction.

Lambert’s cosine law:

The illumination at a point on a surface is proportional to cosine of the angle which ray makes with the normal to the normal to the surface at that point.