PHOTOMETRY

Light is a physicaal quantoty. Hence as other physical quantity light is also must be measurable. The branch of light that deals with the measurement of light called photometry. In photometry, we have to know about some definitions as given below.
LUMINOUS ENERGY: Light is a measurable physical quantity. Just as electric current flows through a conducting wire the light is also the flow of flux or radiant energy called the luminous energy.Light can be taken as aform of energy since light can be converted to other forns of energy and similarly other forms of energy can also be converted to light for examples:

1. PHOTOCEL:It converts light to electrical energy.
2. SOLAR BATTERY:It converts light to electrical energy.
3. BULBS:It changes electrical energy to light energy and heat .

Hence according to the principle of conservation of energy, light must be a form of energy.