Many units are defined for measurement of light. For example candela, lumen, lux, as we will as many more If we’re interested in measuring the Luminous Intensity we use the unit Candela. The spectrum of electromagnetic radiation contains the range of all radiations. This spectrum is arranged in the sequence of increasing frequency or decreasing wavelength. We can’t see all the radiation. The high energy radiations can’t be seen by us. Only the visible rays can be seen by us like a rainbow. Thus, the measurement of light is done in terms of measuring the intensity of light, flux, efficiency, light speed etc. similar the intensity of light is measured by photometry. The measurement of light occurs with the use of two units that physical as we will as subjective units. When light is measured in terms of energy units due to the fact that it is also considered as energy then it is a physical unit. When it is measured on the bases of it is brightness then it is done with subjective unit’s candles or lux etc. Let’s discuss all the measuring units of light as we will as it is different sources .