Question 1

A person with her eye relaxed looks through a diffraction grating at a distant monochromatic point source of light. The slits of the grating are vertical. She sees:

Accepted Answer

A)  one point of light 
B)  a hazy horizontal strip of light of the same color as the source 
C)  a hazy strip of light varying from violet to red 
D)  a sequence of horizontal points of light 
E)  a sequence of closely spaced vertical lines

Question 2

The diagram shows a single slit with the direction to a point P on a distant screen shown. At P, the pattern has its maximum nearest the central maximum. If X and Y are the edges of the slit, what is the path length difference (PX) - (PY)?

Accepted Answer

A)  $\lambda$/2 
B)  $\lambda$ 
C)  3$\lambda$/2 
D)  2$\lambda$ 
E)  5$\lambda$/2

Question 3

Which of the following is true for Bragg diffraction but not for diffraction from a grating?

Accepted Answer

A)  Two different wavelengths may be used 
B)  For a given wavelength, a maximum may exist in several directions 
C)  Long waves are deviated more than short ones 
D)  There is only one grating spacing 
E)  Maxima occur only for particular angles of incidence

Question 4

A plane wave with a wavelength of 500 nm is incident normally on a single slit with a width of 5.0*10-6 m. Consider waves that reach a point on a far-away screen such that rays from the slit make an angle of 1.0$\degree$ with the normal. The difference in phase for waves from the top and bottom of the slit is:

Accepted Answer

A)  0 
B)  0.55 rad 
C)  1.1 rad 
D)  1.6 rad 
E)  2.2 rad

Question 5

Two wavelengths, 800 nm and 600 nm, are used separately in single-slit diffraction experiments. The diagram shows the intensities on a far-away viewing screen as function of the angle made by the rays with the straight-ahead direction. If both wavelengths are then used simultaneously, at which angle is the light on the screen purely 800-nm light?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 6

When light of a certain wavelength is incident normally on a certain diffraction grating the line of order 1 is at a diffraction angle of 25$\degree$. The diffraction angle for the second order line is:

Accepted Answer

A)  25$\degree$ 
B)  42$\degree$ 
C)  50$\degree$ 
D)  58$\degree$ 
E)  75$\degree$

Question 7

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

Question 8

At the second minimum adjacent to the central maximum of a single-slit diffraction pattern the Huygens wavelet from the top of the slit is 180$\degree$ out of phase with the wavelet from:

Accepted Answer

A)  a point one-fourth of the slit width from the top 
B)  the midpoint of the slit 
C)  a point one-fourth of the slit width from the bottom of the slit 
D)  the bottom of the slit 
E)  none of these

Question 9

At a diffraction line phasors associated with waves from the slits of a multiple-slit barrier:

Accepted Answer

A)  are aligned 
B)  form a closed polygon 
C)  form a polygon with several sides missing 
D)  are parallel but adjacent phasors point in opposite directions 
E)  form the arc of a circle

Question 10

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

Question 11

The widths of the lines produced by monochromatic light falling on a diffraction grating can be reduced by:

Accepted Answer

A)  increasing the wavelength of the light 
B)  increasing the number of rulings without changing their spacing 
C)  decreasing the spacing between adjacent rulings without changing the number of rulings 
D)  decreasing both the wavelength and the spacing between rulings by the same factor 
E)  increasing the number of rulings and decreasing their spacing so the length of the grating remains the same

Question 12

Sound differs from light in that sound:

Accepted Answer

A)  is not subject to diffraction 
B)  is a torsional wave rather than a longitudinal wave 
C)  does not require energy for its origin 
D)  is a longitudinal wave rather than a transverse wave 
E)  is always monochromatic

Question 13

If we increase the wavelength of the light used to form a double-slit diffraction pattern:

Accepted Answer

A)  the width of the central diffraction peak increases and the number of bright fringes within the peak increases 
B)  the width of the central diffraction peak increases and the number of bright fringes with the peak decreases 
C)  the width of the central diffraction peak decreases and the number of bright fringes within the peak increases 
D)  the width of the central diffraction peak decreases and the number of bright fringes within the peak decreases 
E)  the width of the central diffraction peak increases and the number of bright fringes within the peak stays the same

Question 14

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 *10-7 m and 5.50 *10-7- m 
B)  between 5.50 *10-7 m and 1.10 *10-7 m 
C)  between 3.30 *10-7 m and 3.85 *10-7 m 
D)  between 3.85 *10-7 m and 4.40 *10-7 m 
E)  greater than 4.40 *10 - 7 m

Exam 36: Diffraction

A person with her eye relaxed looks through a diffraction grating at a distant monochromatic point source of light. The slits of the grating are vertical. She sees:

Which of the following is true for Bragg diffraction but not for diffraction from a grating?

When light of a certain wavelength is incident normally on a certain diffraction grating the line of order 1 is at a diffraction angle of 25 $\degree$ . The diffraction angle for the second order line is:

The dispersion D of a grating can have units:

At the second minimum adjacent to the central maximum of a single-slit diffraction pattern the Huygens wavelet from the top of the slit is 180 $\degree$ out of phase with the wavelet from:

At a diffraction line phasors associated with waves from the slits of a multiple-slit barrier:

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

The widths of the lines produced by monochromatic light falling on a diffraction grating can be reduced by:

Sound differs from light in that sound:

If we increase the wavelength of the light used to form a double-slit diffraction pattern:

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

Exam 36: Diffraction

A person with her eye relaxed looks through a diffraction grating at a distant monochromatic point source of light. The slits of the grating are vertical. She sees:

The diagram shows a single slit with the direction to a point P on a distant screen shown. At P, the pattern has its maximum nearest the central maximum. If X and Y are the edges of the slit, what is the path length difference (PX) - (PY) ?

Which of the following is true for Bragg diffraction but not for diffraction from a grating?

When light of a certain wavelength is incident normally on a certain diffraction grating the line of order 1 is at a diffraction angle of 25 °\degree° . The diffraction angle for the second order line is:

The dispersion D of a grating can have units:

At the second minimum adjacent to the central maximum of a single-slit diffraction pattern the Huygens wavelet from the top of the slit is 180 °\degree° out of phase with the wavelet from:

At a diffraction line phasors associated with waves from the slits of a multiple-slit barrier:

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

The widths of the lines produced by monochromatic light falling on a diffraction grating can be reduced by:

Sound differs from light in that sound:

If we increase the wavelength of the light used to form a double-slit diffraction pattern:

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

When light of a certain wavelength is incident normally on a certain diffraction grating the line of order 1 is at a diffraction angle of 25 $\degree$ . The diffraction angle for the second order line is:

At the second minimum adjacent to the central maximum of a single-slit diffraction pattern the Huygens wavelet from the top of the slit is 180 $\degree$ out of phase with the wavelet from: