 |
Explorations an Introduction to Astronomy Thomas T. Arny | ||||||||
|
|
Instructor
Resources |
||||||||
|
|||||||||
|
|||||||||||||||||||||||||
Chapter
Images
Chapter 12, Figure 5
Figure
12.5
The inverse-square
law. (a) Light spreads out from
a point source in all directions. (b) As photons move out from a source, they are spread over a
progressively larger area as the distance from the source increases. Thus
a given area intercepts fewer photons the farther it is from the source. (c) The area over which light a distance
d from the source is spread
is 4pd2.
