Question 1

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

Question 2

An x-ray beam of wavelength 3*10-11 m is incident on a calcite crystal of lattice spacing 0.3 nm.The smallest angle between crystal planes and the x-ray beam which will result in constructive interference is:

Accepted Answer

A) 2.9° 
B) 5.7° 
C) 12° 
D) 23° 
E) none of these 
A) 2.9° 
B) 5.7° 
C) 12° 
D) 23° 
E) none of these

Question 3

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 
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 4

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 
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 5

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

Question 6

A beam of x rays of wavelength 0.10 nm is found to diffract in second order from the face of a LiF crystal at a Bragg angle of 30 $\degree$.The distance between adjacent crystal planes is about:

Accepted Answer

A) 0.10 nm 
B) 0.20 nm 
C) 0.25 nm 
D) 0.30 nm 
E) 0.40 nm 
A) 0.10 nm 
B) 0.20 nm 
C) 0.25 nm 
D) 0.30 nm 
E) 0.40 nm

Question 7

Monochromatic plane waves of light are incident normally on a single slit.Which one of the five figures below most correctly shows the diffraction pattern observed on a distant screen?

Accepted Answer

A) I 
B) II 
C) III 
D) IV 
E) V 
A) I 
B) II 
C) III 
D) IV 
E) V

Question 8

Monochromatic light is normally incident on a diffraction grating that is 1 cm wide and has 10,000 slits.The first order line is deviated at a 30 $\degree$ angle.What is the wavelength of the incident light?

Accepted Answer

A) 300 nm 
B) 400 nm 
C) 500 nm 
D) 600 nm 
E) 1000 nm 
A) 300 nm 
B) 400 nm 
C) 500 nm 
D) 600 nm 
E) 1000 nm

Question 9

A light beam incident on a diffraction grating consists of waves with two different wavelengths.The separation of the two first order lines is great if:

Accepted Answer

A) the dispersion is great 
B) the resolution is great 
C) the dispersion is small 
D) the resolution is small 
E) none of the above (line separation does not depend on either dispersion or resolution) 
A) the dispersion is great 
B) the resolution is great 
C) the dispersion is small 
D) the resolution is small 
E) none of the above (line separation does not depend on either dispersion or resolution)

Question 10

An N-slit system has slit separation d and slit width a.Plane waves with intensity I and wavelength $\lambda$ are incident normally on it.The angular separation of the lines depends only on:

Accepted Answer

A) a and N 
B) a and $\lambda$ 
C) N and $\lambda$ 
D) d and $\lambda$ 
E) I and N 
A) a and N 
B) a and $\lambda$ 
C) N and $\lambda$ 
D) d and $\lambda$ 
E) I and N

Question 11

A mixture of 450-nm and 900-nm light is incident on a multiple-slit system.Which of the following is true?

Accepted Answer

A) All lines of the 900-nm light coincide with lines of the 450-nm light 
B) All lines of the 450-nm light coincide with lines of the 900-nm light 
C) None of the lines of the 900-nm light coincide with lines of the 450-nm light 
D) None of the lines of the 450-nm light coincide with lines of the 900-nm light 
E) None of the above 
A) All lines of the 900-nm light coincide with lines of the 450-nm light 
B) All lines of the 450-nm light coincide with lines of the 900-nm light 
C) None of the lines of the 900-nm light coincide with lines of the 450-nm light 
D) None of the lines of the 450-nm light coincide with lines of the 900-nm light 
E) None of the above

Question 12

Light of wavelength 550 nm is incident on a diffraction grating that is 1 cm wide and has 1000 slits.What is the dispersion of the m = 2 line?

Accepted Answer

A) 2.0 x 105 rad/m 
B) 2.0 x 104 rad/m 
C) 2.0 x 103 rad/m 
D) 2.0 x 102 rad/m 
E) 2.0 x 101 rad/m 
A) 2.0 x 105 rad/m 
B) 2.0 x 104 rad/m 
C) 2.0 x 103 rad/m 
D) 2.0 x 102 rad/m 
E) 2.0 x 101 rad/m

Question 13

Light of wavelength $\lambda$ is normally incident on a diffraction grating G.On the screen S, the central line is at P and the first order line is at Q, as shown.The distance between adjacent slits in the grating is:

Accepted Answer

A) 3$\lambda$/5 
B) 3$\lambda$/4 
C) 4$\lambda$/5 
D) 5$\lambda$/4 
E) 5$\lambda$/3 
A) 3$\lambda$/5 
B) 3$\lambda$/4 
C) 4$\lambda$/5 
D) 5$\lambda$/4 
E) 5$\lambda$/3

Question 14

The diagram shows a single slit with the direction to a point P on a distant screen (not shown).At P, the pattern has its second minimum (from its 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" 
A) "$\lambda$/2" 
B) "$\lambda$" 
C) "3$\lambda$/2" 
D) "2$\lambda$" 
E) "5$\lambda$/2"

Question 15

A beam of white light (from 400 nm for violet to 700 nm for red)is normally incident on a diffraction grating.It produces two orders on a distant screen.Which diagram below (R = red, V = violet)correctly shows the pattern on the screen?

Accepted Answer

A) I. 
B) II. 
C) III. 
D) IV. 
E) V. 
A) I. 
B) II. 
C) III. 
D) IV. 
E) V.

Question 16

X rays are:

Accepted Answer

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

Question 17

In a double-slit diffraction experiment the number of interference fringes within the central diffraction maximum can be increased by:

Accepted Answer

A) increasing the wavelength 
B) decreasing the wavelength 
C) increasing the slit separation 
D) decreasing the slit width 
E) increasing the slit width 
A) increasing the wavelength 
B) decreasing the wavelength 
C) increasing the slit separation 
D) decreasing the slit width 
E) increasing the slit width

Question 18

To obtain greater dispersion by a diffraction grating:

Accepted Answer

A) the slit width should be increased 
B) the slit width should be decreased 
C) the slit separation should be increased 
D) the slit separation should be decreased 
E) more slits with the same width and separation should be added to the system 
A) the slit width should be increased 
B) the slit width should be decreased 
C) the slit separation should be increased 
D) the slit separation should be decreased 
E) more slits with the same width and separation should be added to the system

Question 19

Consider a single-slit diffraction pattern caused by a slit of width a.There is a minimum at sin$\theta$equal to:

Accepted Answer

A) exactly $\lambda$/a 
B) slightly more than $\lambda$/a 
C) slightly less than $\lambda$/a 
D) exactly $\lambda$/2a 
E) very nearly $\lambda$/2a 
A) exactly $\lambda$/a 
B) slightly more than $\lambda$/a 
C) slightly less than $\lambda$/a 
D) exactly $\lambda$/2a 
E) very nearly $\lambda$/2a

Question 20

The spacing between adjacent slits on a diffraction grating is 3$\lambda$.The deviation $\theta$of the first order diffracted beam is given by:

Accepted Answer

A) sin($\theta$/2)= 1/3 
B) sin($\theta$/3)= 2/3 
C) sin($\theta$)= 1/3 
D) tan($\theta$/2)= 1/3 
E) tan($\theta$)= 2/3 
A) sin($\theta$/2)= 1/3 
B) sin($\theta$/3)= 2/3 
C) sin($\theta$)= 1/3 
D) tan($\theta$/2)= 1/3 
E) tan($\theta$)= 2/3

Exam 36: Diffraction

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

An x-ray beam of wavelength 3*10-11 m is incident on a calcite crystal of lattice spacing 0.3 nm.The smallest angle between crystal planes and the x-ray beam which will result in constructive interference is:

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:

Sound differs from light in that sound:

A beam of x rays of wavelength 0.10 nm is found to diffract in second order from the face of a LiF crystal at a Bragg angle of 30 °\degree° .The distance between adjacent crystal planes is about:

Monochromatic plane waves of light are incident normally on a single slit.Which one of the five figures below most correctly shows the diffraction pattern observed on a distant screen?

Monochromatic light is normally incident on a diffraction grating that is 1 cm wide and has 10,000 slits.The first order line is deviated at a 30 °\degree° angle.What is the wavelength of the incident light?

A light beam incident on a diffraction grating consists of waves with two different wavelengths.The separation of the two first order lines is great if:

An N-slit system has slit separation d and slit width a.Plane waves with intensity I and wavelength λ\lambdaλ are incident normally on it.The angular separation of the lines depends only on:

A mixture of 450-nm and 900-nm light is incident on a multiple-slit system.Which of the following is true?

Light of wavelength 550 nm is incident on a diffraction grating that is 1 cm wide and has 1000 slits.What is the dispersion of the m = 2 line?

Light of wavelength λ\lambdaλ is normally incident on a diffraction grating G.On the screen S, the central line is at P and the first order line is at Q, as shown.The distance between adjacent slits in the grating is:

The diagram shows a single slit with the direction to a point P on a distant screen (not shown).At P, the pattern has its second minimum (from its central maximum).If X and Y are the edges of the slit, what is the path length difference (PX)- (PY)?

A beam of white light (from 400 nm for violet to 700 nm for red)is normally incident on a diffraction grating.It produces two orders on a distant screen.Which diagram below (R = red, V = violet)correctly shows the pattern on the screen?

X rays are:

In a double-slit diffraction experiment the number of interference fringes within the central diffraction maximum can be increased by:

To obtain greater dispersion by a diffraction grating:

Consider a single-slit diffraction pattern caused by a slit of width a.There is a minimum at sin θ\thetaθ equal to:

The spacing between adjacent slits on a diffraction grating is 3 λ\lambdaλ .The deviation θ\thetaθ of the first order diffracted beam is given by:

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An x-ray beam of wavelength 3*10^-11 m is incident on a calcite crystal of lattice spacing 0.3 nm.The smallest angle between crystal planes and the x-ray beam which will result in constructive interference is:

A beam of x rays of wavelength 0.10 nm is found to diffract in second order from the face of a LiF crystal at a Bragg angle of 30 $\degree$ .The distance between adjacent crystal planes is about:

Monochromatic light is normally incident on a diffraction grating that is 1 cm wide and has 10,000 slits.The first order line is deviated at a 30 $\degree$ angle.What is the wavelength of the incident light?

An N-slit system has slit separation d and slit width a.Plane waves with intensity I and wavelength $\lambda$ are incident normally on it.The angular separation of the lines depends only on:

Consider a single-slit diffraction pattern caused by a slit of width a.There is a minimum at sin $\theta$ equal to:

The spacing between adjacent slits on a diffraction grating is 3 $\lambda$ .The deviation $\theta$ of the first order diffracted beam is given by: