Download Sample Problems for Final

Problem 1
NAME: ________________________
A wedge of glass increases in thickness with an angle of 2 mrad. Green light (wavelength
530 nm) illuminates the upper surface of the wedge at normal incidence. Approximately
how far from the edge of the wedge (where it tapers to zero thickness) does the first
maximum in the reflected light occur? Assume that the wedge is surrounded by air, and
that the index of refraction of the glass is n=1.5.
Problem 2
A 10cm high object rests 40cm to the left of a convex lens with a focal length of 20cm. A
second, concave lens with a focal length of -9cm is placed 30cm to the right of the
convex lens. Where is the image of the two-lens system relative to the second lens? Is the
image real or virtual? Is it upright or inverted? What is the absolute value of its height?
Problem 3
Two narrow slits are separated by 10 microns. Light that passes through the slits
illuminates a screen 1 meter away. Two separate colors of light, of approximately equal
intensity, are incident on the slit: yellow light of wavelength 480 nm and red light of
wavelength 640 nm. The central (m=0) maxima for both colors occur on the screen
straight ahead of the slits. How far away from this do you need to go to see purely yellow
light? Purely red light? The first point that is both at a red and yellow maximum?
Problem 4 [25 Points]
A beam of green light (wavelength 532 nm) is split into two beams, with one beam going
straight ahead, and the other diverging at a small angle  relative to the straight-ahead
beam. At a distance of 50cm the deflected beam is reflected back so that it meets the
straight-ahead beam 100cm beyond the point at which they were split. What is the
minimum angle  required so that the two beams exhibit perfectly destructive
interference when they meet?