What is light industrial work?

Light is proportional to reciprocal of distance, but how do i work out what my values should be?

• I now understand that light is proportional to the reciprocal of distance but im confused as to what values i should get. Im doing an investigation whereby i change the height of a lamp, decreasing light intensity but i am unsure of how much to increase the light by etc. i originally chose the heights, 0, 50, 100, 150, 200 (mm) but are these of too big a distance to achieve reliable result i.e a straight line, or near to it on a graph?

• Answer:

  I don't understand the experiment but your 'understanding' is not quite right..... The intensity of the light is inversely (reciprocal) proportional to the square of the distance. This means if you double the distance then the intensity is reduced to 1/4 of its value and trebling the distance reduces the intensity to 1/9, and so on. Hope this helps.