Due Friday May 7th by in class.

A short one to end the semester.

1) Use Excel or Maple to actually add together the cosines or exponentials to describe the 3-slit interference pattern and thus compute the following.
a) The actual intensity distribution as a function of angle, θ.
b) The ratio of the intensity of the main bumps to the intensity of the little bumps.
c) The width (at half maximum intensity) of the main bumps compared to the width of the bumps in the two-slit interference pattern.

2) Red laser light, wavelength 632nm passes through a single slit 0.04mm wide and falls on a screen 1m away. Plot the intensity distribution seen on the screen assuming that the maximum intensity anywhere in the pattern is 1.

3) A mixture of red light, 632nm, green light, 500nm, and blue light, 430nm, falls onto a single slit 0.025mm in width. Assuming that the light is bright enough for you to see it clearly, describe what you will see on a screen 1m away. A picture would be nice, but the words explaining your reasoning are what really counts.

4) When both diffraction and interference are taken into account in the double slit experiment, discuss the effect of increasing
a) The wavelength,
b) The slit separation,
c) The slit width.

5) In a double-slit experiment, the slit separation, d, is 2.0 times the slit width, w. How many bright interference fringes are in the central diffraction envelope? (Remember I am more interested in how you justify your answer than in the number!)

6) People who work with high power optical lasers are at risk from light reflected from lenses in their optical setups.
a) Explain how a thin coating of Magnesium Oxide (MgO), refractive index n = 1.4, can be used to completely eliminate reflection from a glass lens when it is placed in the beam of a λ = 700nm ruby laser.
b) What must be the thickness of the layer?