DP IB Physics: HL

Topic Questions

Syllabus Edition

First teaching 2014

Last exams 2024

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9.2 Single-Slit Diffraction

1
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Light incident on a single slit creates a diffraction pattern on a screen a certain distance away.

What is the definition of a single slit diffraction pattern?

  • A single slit diffraction pattern is represented as dark fringes of light on the screen separated by coloured strips that show areas of constructive and destructive interference.

  • A single slit diffraction pattern is represented as a single white band of light in the centre of the screen with black surrounding it.

  • A single slit diffraction pattern is represented as a series of light and dark fringes which show the areas of maximum and minimum intensity. 

  • A single slit diffraction pattern is represented as a series of wide and narrow strips of light which show the areas of constructive and destructive interference. 

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2
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When white light is diffracted through a single slit which colour appears closest to the central maximum when viewed on a screen?

  • Violet

  • Blue

  • Red

  • Green

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3
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Light of different wavelengths is incident on a single slit. A diffraction pattern is created on a screen a distance away.

What is the relationship between the wavelength of the light and the width of the bright fringe on the diffraction pattern? 

  • Blue light produces a diffraction pattern with the widest fringes

  • Red light produces a diffraction pattern with the widest fringes

  • All wavelengths of light produce bright fringes of equal width

  • Changing the width of the slit is the only variable that affects the width of the bright fringes

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4
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Monochromatic light is incident on a narrow slit and a diffraction pattern of bright and dark fringes is observed on a screen some distance away.

How does making the single slit narrower affect the spacing of the bright fringes on the screen?

  • The fringe spacing increases with diffraction angle away from the central maximum

  • The fringe spacing is narrower

  • The fringe spacing is wider

  • It has no effect

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5
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What is the equation for the angle of diffraction of the first minima for light diffracted through a single slit that creates a diffraction pattern onto a screen?

  • theta space equals space lambda over b

  • n lambda space equals space d sin theta

  • s space equals space fraction numerator lambda D over denominator d end fraction

  • theta space equals space s over d

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6
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Light of the same wavelength is incident on a single slit. The width of the slit is changed. A diffraction pattern for each slit width is observed on a screen some distance away.

Which diffraction pattern represents that of the narrowest slit?

9-2-ib-hl-emcq6-q

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7
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Monochromatic light of different wavelengths is incident on a single slit. A diffraction pattern is observed on a screen some distance away.

Which diffraction pattern represents the longest wavelength of light?

9-2-ib-hl-emcq7-q

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8
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Monochromatic light is incident on a single slit and the interference pattern is observed on a screen some distance away.

What is the expression for the path difference between two rays that interfere destructively at a point P on the screen?

  • fraction numerator n lambda over denominator 2 end fraction

  • n lambda

  • d sin theta

  • fraction numerator lambda D over denominator d end fraction

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9
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Monochromatic light is incident on a single slit with a diffraction pattern created on a screen some distance away.

What small angle approximation is used in obtaining the equation theta space equals space lambda over b to calculate the angle of diffraction of the first minimum of the single slit diffraction pattern?

  • tanθ ≈ sinθ

  • sinθ ≈ θ 

  • tanθ ≈ θ

  • cosθ ≈ θ

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10
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Monochromatic light is incident on a single slit and a diffraction pattern is observed on a screen some distance away.

How does the diffraction pattern change when the single slit and the screen are moved further apart?

  • Fringe intensity is decreased

  • Fringe intensity is increased

  • Fringe width is decreased

  • Fringe width is increased

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The diffraction pattern for light passing through a single slit is shown on the graph below.  

9-2-ib-hl-hmcq1-q9-2-ib-hl-hmcq1-q

What is the fraction numerator s l i t space w i d t h over denominator w a v e l e n g t h space o f space l i g h t end fraction?

  • 0 m

  • 1 × 10−2 m

  • 2 × 10−2 m

  • 100

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2
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Monochromatic light is incident on two slits that are identical. An interference pattern is produced on a screen some distance away. Upon returning to the experiment a Physicist notices that there are fewer maxima now present on the screen.

What aspect of the equipment set up has been changed?

  • The screen and slits have been moved further apart

  • The wavelength of the light used is longer

  • The wavelength of the light used is shorter

  • One of the slits has become blocked

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3
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When monochromatic light is incident on a single slit a diffraction pattern forms on a screen. The width of the slit is increased. 

What are the changes in the width of the central and subsidiary maxima and in the intensity of the central and subsidiary maxima of the single slit diffraction pattern?

 

Width of central maximum

Intensity of central maximum

Width of subsidiary maximum

Intensity of subsidiary maximum

A.

decreases increases decreases increases

B.

increases increases increases decreases

C.

decreases decreases decreases increases

D.

increases increases decreases decreases

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4
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A beam of photons moving in the direction shown is incident on a rectangular slit of width, b. The angle produced at X by the interference pattern of the photons diffracting through the slit is θ

 

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What is the component of the energy of the photons at point X on the screen?

  • E space equals space fraction numerator theta b space over denominator h c end fraction

  • E space equals space theta b

  • E space equals space fraction numerator h c over denominator theta b end fraction

  • E space equals space fraction numerator theta b over denominator c end fraction

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5
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A beam of light of wavelength λ is incident upon a single slit of width w. After passing through the slit, the light is incident on a screen at a distance Q from the slit. 

Which of the following changes, carried out separately, will result in an increased width of the central maxima observed on the screen?

 

λ

w

Q

A.

increase increase increase

B.

decrease increase decrease

C.

decrease decrease decrease

D.

increase decrease increase

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6
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A parallel beam of coherent light of wavelength p nm is incident on a rectangular slit of width p µm. After passing through the slit the light is incident on a screen a distance m away. 

What is the width of the central maximum of the diffraction pattern as measured on the screen?

  • p × 10−6

  • p2 × 10−3

  • 2p2 × 10−3

  • 2p2

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7
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A parallel beam of light of wavelength 400 nm is incident normally on a slit of width b. The distance between the slit and the screen is 0.2 m and the distance of the second order of maximum from the centre of the screen is 10 mm. 

9-2-ib-hl-hmcq7-q

What is the width of the slit?

  • 1 × 10−4 m

  • 1 × 10−2 m

  • 0.1 m

  • 1 m

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8
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A parallel beam of light of wavelength λ passes through a slit of width b. The transmitted light is collected on a screen m away where ≫ b.

What is the distance between the two second-order minima?

  • fraction numerator D lambda over denominator 2 b end fraction

  • fraction numerator 2 D lambda over denominator b end fraction

  • fraction numerator 4 D lambda over denominator b end fraction

  • fraction numerator 8 D lambda over denominator b end fraction

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9
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Radiation is incident on a single rectangular slit. The diffracted beam that emerges from the slit is incident on a screen. Both the slit width and the wavelength of the radiation are tripled. The intensity of the radiation remains the same. 

Which answer option correctly describes the total number of photons incident every second on the screen and the angular width of the central maximum of the diffracted beam?

 

Number of photons incident every second 

Angular width of the central maximum

A

tripled unchanged

B

a third unchanged

C

unchanged tripled

D

tripled a third

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10
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A monochromatic source of light of wavelength λ is incident on a single slit of width b. The interference pattern is visible on the screen where the angle of the third minima is θ.

What is the wavelength of the light?

  • fraction numerator b theta over denominator 6 end fraction

  • fraction numerator b theta over denominator 3 end fraction

  • fraction numerator b theta over denominator 2 end fraction

  • b theta

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1
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In two separate experiments, monochromatic light is incident on a single slit. The diagrams show the interference patterns obtained on a screen far from the slit. In diagram 1, the wavelength of light is λ1 and the slit width is b1. In diagram 2, the wavelength of light is λ2 and the slit width is b2.

9-2-hl-mcq-1-medium-diffraction-patterns

What is the correct expression linking wavelength and slit width of the two interference patterns?

  • λ2 < λ1

  • b2 < b1

  • lambda subscript 1 over b subscript 1 greater than lambda subscript 2 over b subscript 2

  • lambda subscript 1 over b subscript 1 less than lambda subscript 2 over b subscript 2

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2
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Which of the statements are true for single-slit interference? 

  1. Blue light produces a larger angle of diffraction than red light
  2. The smaller the slit width, the larger the angle of diffraction for a constant wavelength 

  • Neither

  • I only

  • II only

  • Both

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3
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Several diffraction experiments are performed with light diffracted through different numbers of slits. Which row. in the table below, correctly matches the number of slits and the intensity pattern observed on the screen?

 

Experiment 1

Experiment 2

Experiment 3

Experiment 4

A.

5-slit diffraction grating

Single Slit

Double Slit

10-slit diffraction grating

B.

10-slit diffraction grating

Single Slit

Double Slit

5-slit diffraction grating

C.

10-slit diffraction grating

Double Slit

Single Slit

5-slit diffraction grating

D.

5-slit diffraction grating

Double Slit

Single Slit

10-slit diffraction grating

9-2-hl-mcq-medium-q3-ans-options-1

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4
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Monochromatic light is incident on a narrow rectangular slit in an optical experiment. The diffracted light is observed on a distant screen. The graph below shows how the intensity of light varies with position on the screen.

9-2-hl-mcq4-medium-q4-diag

The width of the slit is increased. The original diffraction pattern is shown by the solid line.

Which graph shows how the intensity of light observed varies with position on the screen? 

9-2-hl-mcq4-medium-ans-options

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5
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The diagram shows the diffraction pattern for light travelling through a single slit of width 2.0 mm. 

9-2-hl-mcq5-medium-diag

What is the wavelength of the light used?

  • 2.0 cm

  • 2.0 mm

  • 20 μm

  • 20 nm

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6
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White light is diffracted through a single slit.

Which row in the table indicates the correct positions of red (R), violet (V) and white (W) light on the intensity pattern seen on a screen?  

9-2-hl-mcq6-medium-medium-ans-table

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7
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A single slit diffraction pattern is performed several times using light of different colours, slits of different widths and different distances to the screen. Which change will decrease the width of the central peak?

  • Change the light source from red to blue

  • Change the light source from blue to red

  • Make the slit width narrower

  • Move the screen further away

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8
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A parallel beam of coherent light of wavelength λ is incident on a rectangular slit of width b. After passing through the slit the light is incident on a screen a distance D from the slit where is much greater than b.  

What is the width of the central maximum of the diffraction pattern as measured on the screen? 

  • fraction numerator b over denominator D lambda end fraction

  • fraction numerator D lambda over denominator b end fraction

  • fraction numerator 2 b over denominator D lambda end fraction

  • fraction numerator 2 lambda D over denominator b end fraction

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9
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In a diffraction experiment with a single slit, the first minimum is observed at a diffraction angle θ. The intensity of the central maximum of the diffraction pattern is I. The light source stays the same. What is the effect on I and θ of reducing the slit width?

 

θ

I

A.

decreases

increases

B.

increases

decreases

C.

decreases

decreases

D.

increases

increases

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10
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A single slit produces a diffraction pattern. The angle from the centre of the pattern to the first minimum point is Y. The slit width is then halved and the frequency of light is doubled. 

What is the new angle from the centre of the pattern to the first minimum point?

  • 4Y

  • 1 halfY

  • Y

  • 1 fourthY

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