How to measure the intensity of light in flouracent lamp?

Question

To check the efficiency of lamp with reference to input power.To find out heat loss to Environment.

Answer 1

I just read the label !

Answer 2

The instrument you need is called a luxmeter.

The intensity of light is measured in Lux which is equivalent to 1 Lumen/mm^2

This a luxmeter will record a different value based on the distance from the light source, due to the fact that the intensity of energy is inversely proportional to the square of the distance.

a lux meter works by using a silicon, GaAs or selenium wafer which is normally doped from the instrinsic. When light falls on the wafer, it creates a voltage across it by Einstein's photoelectric effect, proportional to the intensity of light incident. An amplifier is used to input the signal to an A to D converter, which then allows the value in Lux to be displayed on a 7 segment display. Most Luxmeters are calibrated to a standard, whereby a light source of a known intensity is placed in a laboratory, and the luxmeter to be calibrated is placed in light of known intensity, allowing any errors to be corrected and therefore calibrating the unit.