1. Define wavelength and frequency in your own words and state the relation between them,
(equation statement). (0.5 point)
2. Describe the pattern observed from diffraction around a straight edge, for the straight
edge/opaque disks. Why do you think this pattern is diffraction and not interference? (1.0
point)
3. When you illuminate the opaque holes in the straight edge/opaque disk using the laser through
the lens, was there a light or dark spot at the center of the screen? (1.0 point)
4. Is there a specific reason for using lasers in this experiment, and not ordinary white light, if yes
what is it? (there may be more than one reason) (1.5 points)
5. For single slit diffraction how would the width of the central maxima or the central bright band
change
a) If the wavelength is increased (1.0 point)
b) If the slit width “a” is increased (1.0 point)
6. Pretend you redid the diffraction grating section and arrived at this data: L = 1m, d = 3.33 x
10-4cm, y (distance from center to first bright spot) = 22.1cm, λ=656nm (red light). (1.5 point)
Now pretend you leave the equipment setup the same but pass blue light (λ=396nm) through the
diffraction grating. What y distance will the blue light be diffracted to? Is this closer to or
farther away from the center? (1.0 point)
7. A light spectrum is formed on the screen using a diffraction grating. The entire apparatus made
up of laser, grating and the screen is now immersed in a liquid with refractive index 1.33. Do
the bright spots on the screen get closer together, farther apart, remain the same or disappear
entirely? Explain (1.5 points)
8. Light with wavelength of λ = 456 nm is incident on a diffraction grating. The screen is placed
at a distance L = 2m from the diffraction grating. The grating has N = 100 parallel slits (used to
calculate d). Find the distance y between the 2nd bright spots or the second order maxima on the
either side of the central bright spot. (2.0 point)
