Experiment 11: Measuring a Human Hair

In this experiment we used the a micrometer and a laser to measure and compare the thickness of a human hair. We began by using the laser and pointing it directly at the hair. We then measured the diffraction of light, the distance our image was from the object, and knew that the wavelength of our laser to be about 670 nm +/- 20 nm.

We then took three trials and on each trial we measured the distance from the hair to the image on a board, the node number, y_m, and lamda which we took to be 670 nm +/- 20nm. We then used the equation d=L*m*(lamda)/y to find the thickness of the hair d.

Trial	Length (L, m)	Node Number (m)	y (m)	Lamda (m, +/- 20 nm)	d (m)
1	1.68	4	0.063	6.7E-07	7.15E-05
2	2	4	0.076	6.7E-07	7.05E-05
3	3.62	3	0.11	6.7E-07	6.61E-05

We found after three trails the thickness of the hair to be about  6.9*10^(-5) meters thick. This fits within our estimation that the thickness of the hair would be between 1.7*10^(-5) to 1.8*10^(-4) meters thick. Using the micrometer we found the thickness of the hair to be about 7*10^(-5) meters which falls well within our trials for the thickness of the hair.