Photometric law of distance - inverse square law

Principle

The luminous intensity emitted by a punctual source is determined as a function of distance.

Benefits

• Find out how exactly it becomes darker with increasing distance from a light source
• Get results fast and reproducible with a data-logging system
• Analize results easily and compare them to theory using a computer

Tasks

1. The luminous intensity emitted by a punctual source is determined as a function of distance from the source.
2. The photometric law of distance is verified by plotting illuminance as a function of the reciprocal value of the square of the distance.

Learning objectives

• Luminous flux
• Quantity of light
• Luminous intensity
• Illuminance
• Luminance