Single Slit Diffraction and Resolution Practice
1. Describe the change in width of the central maximum of the single-slit diffraction pattern as the width
of the slit is made smaller.
2. Would orange light or blue light produce a wider diffraction pattern? Explain why.
3. Why are orbiting telescopes designed for use in all of the electromagnetic spectrum except for radio?
4. Globular clusters (such as M14 shown below), are spherical groupings of stars that form a ring around
the Milky Way. Because there can be millions of stars in a single cluster and because they are distant,
resolving individual stars within a cluster can be a challenge. Of the following conditions, which would
make it easier to resolve the component stars? Which would make it more difficult?
a) The number of stars per unit volume is half as great.
b) The cluster is twice as far away.
c) The cluster is observed in the UV potion instead of the visible
region of the EM spectrum.
d) The telescope’s mirror or lens is twice as wide.
5. A diffraction pattern forms when light passes through a single slit. The wavelength of
the light is 675 nm. Determine the angle that locates the first dark fringe when the slit
is a) 1.8 x 10-4 m b) 1.8 x 10-6 m.
6. Light that has a wavelength of 668 m passes through a slit 6.7 x 10 -6 m wide and falls
on a screen that is 1.85 m away. What is the distance on the screen from the central
bight fringe to the third dark fringe on either side?
7. How many dark fringes will be produced on either side of the central maximum if light (=651 nm) is
incident on a single slit that is 5.47 x 10-6 m wide?
8. In a single-slit diffraction pattern, the central fringe is 450 times as wide as the slit. The screen is
18 000 times further from the slit than the slit is wide. What is the ratio /W, where  is the wavelength
of the light shining through the slit and W is the width of the slit? Assume that the angle that locates a
dark fringe on the screen is small, so that sin  tan.
9. You are looking down at the earth from inside a jetliner flying at an altitude of 8690 m. The pupil of
your eye has a diameter of 2.00 mm. Determine how far apart two cars must be on the ground if you
are to have any hope of distinguishing between them in a) red light (=665 nm) and b) violet light
(=405 nm).
10. Astronomers have discovered a planetary system orbiting the star Upsilon Andromedae, which is a
distance of 4.2 x 1017 m from the earth. One planet is believed to be located at a distance of 1.2 x 10 11
m from the star. Using the visible light with a vacuum wavelength of 550 nm, what is the minimum
necessary aperture diameter that a telescope must have so that it can resolve the planet and the star?
11. A spotlight sends red light to the moon (=694.3 nm). At the surface of the moon, which is 3.77 x 10 8
m away, the light strikes a reflector left there by astronauts. The reflected light returns to earth, where
it is detected. When it leaves the spotlight, the circular beam of light has a diameter of about 0.20 m,
and diffraction causes the beam to spread as the light travels to the moon. In effect, the first circular
dark fringe in the diffraction pattern defines the size of the central bright spot on the moon. Determine
the diameter (not the radius) of the central bright spot on the moon.