optics.gif (6954 bytes)

INVERSE SQUARE LAW
(Propagation of Light)






EQUIPMENT
    redball.gif (326 bytes) Wire Model of Inverse Square Law
    redball.gif (326 bytes) Lamp
    redball.gif (326 bytes) Screen
    redball.gif (326 bytes) Power Supply
  


NARRATIVE
                 redball.gif (326 bytes)  Wire Inverse Square Model
               The wire model is a section of a sphere of radius 2 units. The surface areas at 1 unit and at 2 units from the center are shown. These surfaces are divided into areas of 1 unit square. This model is also useful to illustrate flux from a point source through a spherical surface.

                redball.gif (326 bytes)  Wire Frame and Lamp Demonstration
               Connect the power supply to 100 VDC. Place the wire frame over 1 section of the screen to show screen area = 4 times frame area. Position the frame at one-half the distance between the light source and screen to show that the projected frame area is squared. The light source is  connected to 100 VDC.