Measuring a human hair

In this lab, we determined the width of a human hair by utilizing the properties of diffraction from a light source from two slit.  Interference between the light propograting from two source points will result in areas of maximum and minimum intensities.

The Setup:

A notecard has a hole punched through it.  A human hair is attached over the hole vertically and splits the single hole into two.  The width of the hair, 'd', is the width between the newly created dual source point.  A laser will be focused on the hair and will be split by the hair.  The laser will now propogate from two source points and interfere with itself.



Here, we are observing and marking diffraction maximas

A laser is focused on the hair that is attached to a notecard.
An interference pattern is now projected onto the whiteboard.



Measuring a group of maximum intensities.

A diagram of the experiment with known and calculated values. 
We have solved for the distance, d, between the two source points - the width of the human hair.

Conclusion:

We find that the human hair used is approximately 122.4 micrometers and are now familiar with the order of magnitude of the width of a human hair.