Higher Physics

Particles and Waves - Activity 7

Variation of light intensity with distance away from a point source of light

Aim - To investigate the relationship between the light intensity with the distance away from a point source of light.     Instructions 
The light detector is connected to the light intensity meter and is placed 50 cm from the light source.
  • Take a reading of the light intensity when the light detector is at a distance of 50 cm.
  • Use the mouse to click and drag the light detector to a new position closer to the lamp. The light detector remains in the position when the mouse is released.
  • Take a reading of the light intensity when the light detector is at this distance.
  • Repeat these measurements for different distances between the detector and lamp.
  • Plot a graph of light intensity against distance from the lamp.
  • Plot a second graph of intensity against 1/(distance)2  to find the relationship between light intensity and distance from the lamp.
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