Question 1

Coherent light of a single frequency passes through a double slit with a separation d, to produce a pattern on a screen a distance D from the slits. What would cause the separation between adjacent minima on the screen to increase?

Accepted Answer

A)  increase the index of refraction of the medium in which the setup is immersed 
B)  increase the separation d between the slits 
C)  increase the distance D 
D)  increase the frequency of the incident light

Question 2

For an angle of one degree, to how many significant figures do sin θ and θ (in radians) agree?

Accepted Answer

A)  3 
B)  4 
C)  5 
D)  6 
E)  7

Question 3

A thin film of magnesium fluoride (n = 1.38) is applied to glass (n = 1.50). If the thickness of the film is 100 nm, for what visible wavelength will it be nonreflecting?

Accepted Answer

A)  600 nm 
B)  578 nm 
C)  552 nm 
D)  504 nm 
E)  491 nm

Question 4

Max von Laue is known for his work with

Accepted Answer

A)  double-slit interference. 
B)  single-slit diffraction. 
C)  x-ray crystallography. 
D)  holography. 
E)  magnetic resonance imaging.

Question 5

In a single-slit experiment, light of wavelength 500 nm is used to produce a diffraction pattern on a screen 4.0 m away. If the distance between both third-order minima is 6.0 cm, what is the slit width?

Accepted Answer

A)  2.0 × 10-4 m 
B)  1.0 × 10-4 m 
C)  4.0 × 10-4 m 
D)  0.67 × 10-4 m 
E)  0.44 × 10-4 m

Question 6

A laser beam passes through a grating and produces a first-order maximum at an angle of 25°. At what angle is the second-order maximum?

Accepted Answer

A)  75° 
B)  58° 
C)  50° 
D)  35° 
E)  27°

Question 7

What kind of image does a holographic plate produce for the viewer?

Accepted Answer

A)  real 
B)  virtual 
C)  may be either virtual or real

Question 8

A thin film of soapy water (n = 1.37) is held vertical. Light of wavelength 600 nm is reflected from the film and horizontal dark lines appear. What is the difference in thickness of the soap film from one band to the next?

Accepted Answer

A)  600 nm 
B)  438 nm 
C)  300 nm 
D)  219 nm 
E)  900 nm

Question 9

A general condition for two coherent waves to undergo destructive interference is that

Accepted Answer

A)  their phase difference is zero. 
B)  their phase difference is π/2 rad. 
C)  their phase difference is ±π/2 rad. 
D)  their phase difference is an even integral multiple of π rad. 
E)  their phase difference is an odd integral multiple of π rad.

Question 10

A single slit of width 0.030 mm is used to produce a diffraction pattern of 500 nm light on a screen at a distance of 2.00 m from the slit. What is the width of the central maximum?

Accepted Answer

A)  1.7 cm 
B)  3.3 cm 
C)  6.7 cm 
D)  1.5 mm 
E)  3.0 mm

Question 11

What is the smallest thickness of a coating of magnesium fluoride (n = 1.38) applied to glass (n = 1.50) that gives minimum reflection for 600 nm light?

Accepted Answer

A)  600 nm 
B)  300 nm 
C)  435 nm 
D)  109 nm 
E)  100 nm

Question 12

A Michelson interferometer is used to measure the index of refraction of a gas by counting interference fringes as the gas is slowly leaked into a transparent vessel placed in one arm of the interferometer. The vessel initially contains a vacuum, and as the gas is let in, 397 bright fringes are counted. That is, the central region of the screen changes from bright to dark and back to bright 397 times. If the wavelength of light used is 560 nm, and the vessel containing the gas is 25.0 cm long, what is the index of refraction of the gas?

Accepted Answer

A)  1.000111 
B)  1.000222 
C)  1.000445 
D)  1.000889 
E)  1.00178

Question 13

When scattering 0.328 nm x-rays off a crystal, the first interference maximum occurs at an angle of 23.0 degrees relative to the crystal surface. At what angle does the second maximum occur?

Accepted Answer

A)  51.4° 
B)  46.0° 
C)  34.5° 
D)  There is no second maximum.

Question 14

When the slit width is doubled, what happens to the width of the central maximum in a single-slit diffraction pattern? Assume small angles.

Accepted Answer

A)  nothing 
B)  it doubles 
C)  it halves 
D)  it quadruples 
E)  it quarters

Question 15

What is the highest order maximum possible using a grating with 600 slits per mm for a wavelength of 700 nm?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 16

A two-slit apparatus is illuminated with red light of wavelength 660 nm, and 9 interference maxima are observed within the 4.5 cm-wide central diffraction maximum on a distant screen. If blue light of wavelength 440 nm is used instead, how many fringes will there be in the new central diffraction maximum?

Accepted Answer

A)  3 
B)  13 
C)  9 
D)  6

Question 17

Holography was invented by

Accepted Answer

A)  Max von Laue. 
B)  Sir David Brewster. 
C)  Rosalind Franklin. 
D)  Dennis Gabor. 
E)  Bill Gates.

Question 18

Light from a HeNe laser (632.8 nm wavelength) is directed upon a straightened strand of human hair, 7.5 m from the wall. By examining the diffraction pattern produced on the wall, the diameter of the hair can be determined (the diffraction pattern thus produced has minima in the same locations as if the hair were a slit of the same width in an otherwise opaque barrier). If the central diffraction maximum is measured to be 14.6 cm wide, what is the diameter of the hair?

Accepted Answer

A)  65 µm 
B)  32.5 µm 
C)  43.3 µm 
D)  86.6 µm

Question 19

Light of wavelength 450 nm produces a first-order maximum at 27° when viewed through a grating. At what angle would a first-order maximum occur for a wavelength of 600 nm viewed through this grating?

Accepted Answer

A)  54° 
B)  40° 
C)  36° 
D)  37° 
E)  14°

Question 20

If light of wavelength 690 nm is used in a double-slit experiment with slit separation 0.206 mm, what angle separates the two fourth-order maxima?

Accepted Answer

A)  0.768° 
B)  3.07° 
C)  0.307° 
D)  1.54° 
E)  0.154°

Exam 25: Interference and Diffraction