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A LevelPhysicsCIEExam Questions8. Superposition8.2 Diffraction & Interference

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First teaching 2020

Last exams 2024

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Diffraction & Interference (CIE A Level Physics)

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8.2 Diffraction & Interference

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8.2 Diffraction & Interference

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11 mark

Which of the following is the definition of diffraction?

  • change of direction when waves cross the boundary between one medium and another

  • splitting of white light into colours

  • addition of two coherent waves to produce a stationary wave pattern

  • bending of waves around an obstacle

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21 mark

Two fringes were created on a screen in a double-slit experiment; the distances were too small to measure.

 Which of the following would increase the distance between the fringes?

  • increasing the frequency of the light source

  • increasing the distance between the light source and the slits

  • increasing the distance between the slits and the screen

  • increasing the distance between the slits

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31 mark

The diagram shows the pattern of waves. The source of the waves was unable to be seen.

cie-ial-images398png

Which of the following would cause this pattern?

  • diffraction only

  • interference only

  • coherence only

  • diffraction and interference

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41 mark

An atomic lattice has a spacing of around 10-10 m, which electromagnetic wave would cause the most significant diffraction effect?

  • X-ray

  • infra-red

  • microwave

  • ultraviolet

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51 mark

A ripple tank was used to demonstrate plain wavefronts passed through a gap, as shown in the diagram.

cie-ial-images399png

Which property would be different at S compared to T?

  • frequency

  • amplitude

  • wavelength

  • velocity

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61 mark

A student investigates the interference of light using two identical green LEDs.

 Which statement would explain why the investigation will not work ?

  • the light waves from the sources have a range of wavelengths

  • the light waves from the sources are not monochromatic

  • the light waves from the sources are not coherent

  • the light waves from the sources do not have the same amplitude

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71 mark

A diffraction pattern is observed when monochromatic light was incident on a diffraction grating.

 Which row describes the effect of replacing the grating with one that has more lines per metre?

 

Number of orders of diffraction visible

Angle between first and second orders of diffraction

A

B

C

D

increases

increases

decreases

decreases

increases

decreases

increases

decreases

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    81 mark

    Two loudspeakers are connected to a signal generator, as shown in the diagram.

    cie-ial-images400png

    As the student walks between S to T she notices that the loudness of the sound increases then decreases repeatedly.

     Why does the loudness change?

    • polarisation of the sound waves

    • reflection of the sound waves

    • diffraction of the sound waves

    • interference of the sound waves

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    91 mark

    When a wave passes an obstruction diffraction can be observed, this effect is greatest when the wavelength and obstruction are similar in size.

     When waves are travelling through the air, which of the following would best demonstrate diffraction?

    • radio waves passing a copper wire

    • visible light waves passing a gate post

    • microwaves passing a steel post

    • sound waves passing human hair

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    101 mark

    A student set up an experiment with a diffraction grating. They put a narrow beam of monochromatic light incident along the normal. They found that the third-order diffracted beams are formed at angles of 45° to the original direction.

     Which of the following gives the highest order of diffracted beam produced by this grating ?

    • 6th

    • 5th 

    • 4th 

    • 3rd 

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    11 mark

    Two wave generators are placed at points S and R to produce water waves with an identical wavelength. At point T both waves have the same amplitude. The distances from S to T and R to T are shown on the diagram below

    cie-ial-images401png

    As the student walks between S to T she notices that the loudness of the sound increases then decreases repeatedly.

     What is the wavelength of the waves when the wave generators are in phase and the amplitude at T is zero?

    • 6 cm

    • 4 cm 

    • 3 cm 

    • 2 cm

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    21 mark

    A diffraction grating with 1000 lines per cm has light passed through it. An identical light source is also passed through two slits 0.5 mm apart.

     Both will produce intensity maxima and minima on a screen.

     Which of the following statements about the separation and sharpness of the maxima is correct?

    • the diffraction grating maxima are more widely spaced and are less sharp than the two-slit maxima

    • the diffraction grating maxima are less widely spaced and are sharper than the two-slit maxima

    • the diffraction grating maxima are more widely spaced and are sharper than the two-slit maxima

    • the diffraction grating maxima are less widely spaced and are less sharp than the two-slit maxima

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    31 mark

    The effect of a double slit on monochromatic light is observed by set up in the diagram

    cie-ial-images402png

    Interference fringes are seen on the screen.

     Which of the following changes would increase the distance between the adjacent fringes?

    • decrease the width of each slit

    • decrease the distance between the two slits

    • use light of a higher frequency

    • move the screen closer to the double-slit

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    41 mark

    The equipment was set up as in the diagram to investigate the interference of a double slit.

    cie-ial-images403png

    Which of the following changes would increase the fringe spacing?

    • decreasing the wavelength of the light

    • decreasing distance y

    • decreasing distance x

    • decreasing the distance w

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    51 mark

    A beam of monochromatic light is directed at a diffraction grating as shown in the diagram

    cie-ial-images404png

    Which of the following diagrams show the possible directions of the light that will give maximum intensity ?

    cie-ial-physics-images-8-2-m-q5-answer

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      61 mark

      A beam of monochromatic light with a wavelength of 690 nm is directed at a diffraction grating with 300 lines per mm as shown in the diagram

      cie-ial-images409png

      This set up produces a series of maxima on the screen, what is the greatest number that can be observed?

      • 9

      • 8

      • 5

      • 4

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      71 mark

      A student is investigating the interference of waves. They set up coherent waves produced at points S and T and travel outwards in all directions.

       The line XY is halfway between S and T and perpendicular to the joining line S and T. The distance XY is much greater than the distance ST.

      cie-ial-images410png

      Which line or lines would an interference pattern be seen?

      • WZ only

      • XY only

      • Both XY and WZ

      • Neither XY or WZ

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      81 mark

      Certain circumstances will produce visible interference fringes from two light sources.

       Which of the following conditions will enable visible interference fringes to be seen?

       

      • using one light which is polarised at right angles to light from the other source

      • using incoherent sources

      • using a blue light source

      • using sources from which the light does not overlap

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      91 mark

      Monochromatic light with a wavelength of 600 nm is observed through a diffraction grating with 500 lines per mm.

       The light is passed through a narrow slit the lines from the slit is parallel to the grating. The light goes through the slit then the grating.

      cie-ial-images415png

      The observer changes position to; R – parallel with the grating, S – opposite the slit, T – parallel to the grating on the opposite side.

       What is the number of images he would see?

      • 7

      • 6

      • 4

      • 3

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      101 mark

      Monochromatic light produces interference fringes with a separation of x on a screen with distance D with a pair of slits with separation a.

      The student doubles a and D.

      What would be the new fringe separation?

      • 2x

      • 4x

      • x

      • x over 2

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      11 mark

      Yellow light with a wavelength of 600 nm is used in a diffraction grating experiment. The grating has a separation of 2.00 μm.

      cie-ial-images416png

      What would be the angular separation between the first order and second order maxima?

      • 54.3°

      • 36.9°

      • 19.4°

      • 17.5°

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      21 mark

      Yellow light with a wavelength of 600 nm is used in an experiment to show interference fringes produced by double-slit interference. The fringe separation in 4.0 mm and the separation of the slits is 0.60 mm.

       What would be the distance between the double slit and the screen?

      • 4.0 m

      • 2.5 m

      • 0.4 m 

      • 0.25 m

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      31 mark

      An experiment was set up to investigate two-source interference. Microwaves of wavelength λ passed through S1 and S2.

      cie-ial-images417png

       

      The detector is moved in the direction of the arrow from Y to W. The signal detected decreased to point W then starts to increase again as it continues past W.

      Which of the following would be the equation to determine the position of point W?

      • S subscript 2 W minus S subscript 1 W equals lambda over 2

      • S subscript 2 W minus S subscript 1 W equals lambda

      • Y W equals lambda over 2

      •  Y W equals lambda

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      41 mark

      An experiment was set up to investigate light passing through a diffraction grating with slit spacing d. The fringe pattern was observed on a screen.

      cie-ial-images418png

      Which of the following gives the angle between the two first-order lines?

      • 2 space s i n to the power of negative 1 end exponent open parentheses fraction numerator lambda over denominator 2 d end fraction close parentheses

      • 2 space sin to the power of negative 1 end exponent open parentheses lambda over d close parentheses

      • sin to the power of negative 1 end exponent open parentheses fraction numerator lambda over denominator 2 d end fraction close parentheses

      • sin to the power of negative 1 end exponent open parentheses lambda over d close parentheses

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      51 mark

      Yellow light with a wavelength of 600 nm is used in an experiment to show interference fringes produced by double-slit interference. The fringe separation is 4.0 mm on the screen.

       What would be the fringe spacing be if the wavelength is changed to 400 nm and the separation of the slits is doubled ?

      • 12.0 mm

      • 5.3 mm

      • 3.0 mm 

      • 1.3 mm

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      61 mark

      A student carried out an experiment on monochromatic light with a wavelength of 5.30 × 10–7 m. They set up the source so that it was incident normally to the diffraction grating.

      The student observed that the first-order maximum of was 15.4° to the direction of the incident light.

       What would be the angle between the first order and second order maxima?

      • 32.1°

      • 16.7°

      • 15.4°

      • 7.6°

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      71 mark

      A student carried out an experiment on Young's slits using a laser light. There is also a section of the pattern produced with a ruler placed next to it.

      cie-ial-images420png

      What is the wavelength of the light?

      • 540 nm

      • 3.4 µm

      • 480 nm

      • 3.2 µm

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      81 mark

      A student carried out an experiment on interference patterns from a diffraction grating and double-slit and compared the results.

       Using the diffraction grating, yellow light with the first order at 30° to the normal and the grating was seen.

       Using the same light interference fringes were seen on a screen 1.0 m from the double slit. The slit separation was 500 times greater than the line spacing of the grating.

       What fringe separation did the student see on the screen?

      • 10 cm

      • 1 mm

      • 250 nm

      • 10 μm

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      91 mark

      The wavelength of monochromatic light can be determined using a diffraction grating. This is shown in the diagram.

      cie-ial-images422png

      The angle between the first-order diffraction maxima is 60°, and the spacing of the slits is 1.15 × 10–6 m.

       What is the wavelength of the light?

      • 575 nm

      • 498 nm

      • 996 nm

      • 287 nm

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      101 mark

      When a parallel beam of white light is incident to normally on a diffraction grating the second-order and third-order spectra partially overlap.

       When the second order wavelength is 600 nm, which of the following third-order wavelengths would appear at the same angle?

      • 900 nm

      • 600 nm

      • 400 nm

      • 300 nm

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