Particles and Waves - Inverse Square Law

Question 1

What is irradiance?

Answer 1

The power per unit area incident on a surface

Question 2

What does a point source do in terms of radiation?

Answer 2

It emits radiation in all directions

Question 3

Irradiance is inversely proportional to…

Answer 3

The square of the distance from a point source

Question 4

Steps of an experiment to verify inverse square law

Answer 4

• set up a clear lamp, the point source, over a black surface in dark room with light sensor and ruler.
• Place light detector at a distance from the lamp
• Measure this distance and the intensity of the light at this distance
• Repeat at different distances
• As area of light is a constant, light sensor reading can be taken as irradiance