Ok-3 Inverse Square Law

Aim

To demonstrate the inverse square law

Apparatus

  • Optical bench
  • Screen
  • Camera
  • Special Square objects
  • Special Screen and camera mount
  • Power supply

Inverse Square Apparatus 1 Inverse Square Pic 1 Inverse Square Pic 2

Inverse Square Apparatus and Projections.

Description

A light source casts a shadow onto a reference grid. The CCD camera is attached at a fixed distance from this grid and focused on the image. The source to grid distance is adjusted to 20cm and the object moved to 10 cm from the source so that the shadow covers exactly 4 squares. The voltage to the light source is adjusted so as not to produce flaring in the camera image. If the distance between the source and grid is doubled the shadow is seen to now cover 16 squares.