Discussion
My experiment was based on the Inverse Square Law,
which applies to electromagnetic waves, such as light and radio waves,
which spread outwards as they travel away from their source. So basically
the intensity or the strength of such waves is inversely proportional to
the square of the distance of the wave from its’ source, so in my experiment
I started out with a 60 watt bulb, a 13.5 watt bulb, and a laser pointer.
As I found in all three trials for all three light sources I did not get
the results of the Inverse Square Law. For ex., for the 60 watt bulb I had
an average of 239mV at 1m. And then at 2m I had an average of 169mV. However,
according to the Inverse Square Law, I should have had a reading of approximately
60mV at 2m.
1m. → 239mV
2m. → 1/4 x 239mV= 60 mV
For the 13.5 watt energy saving bulb, I had an
average reading of143mV at 1m distance. Then, when I measured at 2m distance,
I had a reading of 78mV, but according to the Inverse square law, I should
have had a reading of approximately 36mV at 2m.
1m → 143mV
2m → 1/4 x 143mV= 36mV
Then when I went on to test the laser light, I
got an average reading of 302mV at 1m. Then, when I measured the light intensity
from a distance of 2m, I had an average reading of 301mV. And then, after
I did the experiment I found out that the Inverse Square Law does not
apply to narrow beam light sources such as the laser because it is based
on the idea that incandescent bulbs give off many wavelengths of light
and spreads out, whereas a laser light only has one wavelength of light.
The Inverse Square Law only
seems to apply if you have no reflection of the light (everything has to
be black.) Also, it seems that the 60 watt bulb and the 13.5 watt bulb were
not equal in intensity. According to my results, the 13.5 watt light bulb
actually had a lower light intensity than the 60 watt bulb. Also, when I
touched the 60 watt light bulb after 30 minutes, it was extremely hot, but
when I touched the 13.5 watt bulb it wasn’t hot.
Next year, if I continue this project I would
use a 100 watt bulb and an energy efficient bulb. I would make sure to
do this project in a pitch black with no furniture.