Question 1

The largest x-ray wavelength that can be diffracted by crystal planes with a separation of 0.316 nm is:

Accepted Answer

A)  0.158 nm 
B)  0.316 nm 
C)  0.474 nm 
D)  0.632 nm 
E)  1.26 nm D

Question 2

The dispersion D of a grating can have units:

Accepted Answer

A)  cm 
B)  1/nm 
C)  nm/cm 
D)  radian 
E)  none of these B

Question 3

A diffraction grating just resolves the wavelengths 400.0 nm and 400.1 nm in first order. The number of slits in the grating is:

Accepted Answer

A)  400 
B)  1000 
C)  2500 
D)  4000 
E)  not enough information is given D

Question 4

If 550-nm light is incident normally on a diffratction grating and exactly 6 lines are produced. The ruling eparation must be:

Accepted Answer

A)  between 2.75  x10-7m and 5.50  x10-7 m 
B)  between 5.50  x10-7m and 1.10  x10-7 m 
C)  between 3.30  x10-7and 3.85  x10-7 m 
D)  between 3.85  x10-7m and 4.40  x10-7 m 
E)  greater than 4.40  x10-7 m

Question 5

As more slits with the same spacing are added to a multiple-slit system the lines:

Accepted Answer

A)  spread further apart 
B)  move closer together 
C)  become wider 
D)  becomes narrower 
E)  do not change in position or width

Question 6

X rays are:

Accepted Answer

A)  electromagnetic waves 
B)  negatively charged ions 
C)  rapidly moving electrons 
D)  rapidly moving protons 
E)  rapidly moving neutrons

Question 7

When 450-nm light is incident normally on a certain double-slit system the number of interference maxima within the central diffraction maximum is 5. When 900-nm light is incident on the same slit system the number is:

Accepted Answer

A)  2 
B)  3 
C)  5 
D)  9 
E)  10

Question 8

In a Young's experiment, it is essential that the two beams:

Accepted Answer

A)  have exactly equal intensity 
B)  be exactly parallel 
C)  travel equal distances 
D)  come originally from the same source 
E)  be composed of a broad band of frequencies

Question 9

The rainbow seen after a rain shower is caused by:

Accepted Answer

A)  diffraction 
B)  interference 
C)  refraction 
D)  polarization 
E)  absorption

Question 10

Huygens' construction can be used only:

Accepted Answer

A)  for light 
B)  for an electromagnetic wave 
C)  if one of the media is vacuum (or air) 
D)  for transverse waves 
E)  for all of these and other situations

Question 11

Interference of light is evidence that:

Accepted Answer

A)  the speed of light is very large 
B)  light is a transverse wave 
C)  light is electromagnetic in character 
D)  light is a wave phenomenon 
E)  light does not obey conservation of energy

Question 12

The resolving power R of a grating can have units:

Accepted Answer

A)  cm 
B)  degree/nm 
C)  watt 
D)  nm/cm 
E)  watt/nm

Question 13

If two light waves are coherent:

Accepted Answer

A)  their amplitudes are the same 
B)  their frequencies are the same 
C)  their wavelengths are the same 
D)  their phase difference is constant 
E)  the difference in their frequencies is constant

Question 14

The shimmering or wavy lines that can often be seen near the ground on a hot day are due to:

Accepted Answer

A)  Brownian movement 
B)  reflection 
C)  refraction 
D)  diffraction 
E)  dispersion

Exam 19: Diffract and Interference