Distance vs brightness

When an object emits light it can be modeled as a point source. As the light travels away from the light it is spread out over an area..

In this activity you will investigate how intensity changes with distance from the source

You will need

a balloon

a permanent marker

a 1.5 cm square frame

You need to place the frame on the uninflated balloon and draw several small dots. Try to make them as dark as possible

Blow up the balloon and then let the air out until is is just inflated. Measure the diameter.

Place the frame over the section with the dots and could how many dots fit in the frame. Record you results in a table. continue to increase the diamter and take another reading. Try to place the frame in the same position.

Plot your data on using a spread sheet.

What do you notice about the darkness of the dot? What is happening?