Question 1

In a diffraction-grating experiment the maxima are produced on a screen.

What causes the separation of the maxima of the diffraction pattern to decrease?

  A  

using light with a longer wavelength

  B  

increasing the distance between the screen and grating


  C  

increasing the distance between the source and grating


  D  

using a grating with a greater slit separation

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Question 2

White light passes through a single narrow slit and illuminates a screen.

What is observed on the screen?

  A  

a set of equally spaced white fringes

  B  

a central maximum made up of a spectrum surrounded by white fringes

  C  

a white central maximum surrounded by coloured fringes


  D  

a single narrow white line

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Question 3

When a monochromatic light source is incident on two slits of the same width an interference pattern is produced.

One slit is then covered with opaque black paper.

What is the effect of covering one slit on the resulting interference pattern?

  A  

the intensity of the central maximum will increase


  B  

the width of the central maximum decreases

  C  

fewer maxima are observed

  D  

the outer maxima become wider

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Question 4

When light of wavelength 5.0 × 10−7 m is incident normally on a diffraction grating the fourth-order maximum is observed at an angle of 30°.

What is the number of lines per mm on the diffraction grating?

  A  

2.5 × 102

  B  

2.5 × 105

  C  

1.0 × 103

  D  

1.0 × 106

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Question 5

Monochromatic light of wavelength 490 nm falls normally on a diffraction grating that has 6 x 105 lines per metre. Which one of the following is correct?

  A  

the first order is observed at angle of diffraction of 17o

  B  

the second order is observed at angle of diffraction of 34o

  C  

the third and higher orders are not produced


  D  

A grating with more lines per metre could produce more orders


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Question 6

In a Young’s double-slit experiment, monochromatic light is incident on two narrow slits and the resulting interference pattern is observed on a screen.

Which change decreases the fringe separation?

  A  

decreasing the separation between the two slits

  B  

increasing the distance between the slits and the screen


  C  

using monochromatic light of higher frequency


  D  

using monochromatic light of longer wavelength


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Question 7

A diffraction grating is illuminated normally.

The second-order maximum for light of wavelength 650 nm occurs at the same angle as the third-order maximum for light of wavelength λ.

What is λ?

  A  

217 nm

  B  

325 nm

  C  

433 nm

  D  

975 nm

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Question 8

A narrow beam of monochromatic light is incident normally to a diffraction grating.

The first-order diffracted beam makes an angle of 20° with the normal to the grating.

What is the highest order visible with this grating at this wavelength?

  A  

2

  B  

3

  C  

4

  D  

5

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Question 9

Monochromatic light is incident normally on a diffraction grating that has 4.50 × 105 lines m−1.

The angle between the second-order diffraction maxima is 44°.

What is the wavelength of the light?

  A  

208 nm

  B  

416 nm

  C  

772 nm

  D  

832 nm

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Question 10

Monochromatic electromagnetic radiation of wavelength 5.8 × 10–7 m is incident normally on a diffraction grating with  3.0 × 105 lines per metre. 

What is the highest order maximum produced?

  A  

5

  B  

6

  C  

10

  D  

13

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Question 11

A diffraction grating has 500 lines per mm. When monochromatic light is incident normally on the grating the third-order spectral line is formed at an angle of 60° from the normal to the grating.

What is the wavelength of the monochromatic light?

  A  

220 nm

  B  

580 nm

  C  

960 nm

  D  

1700 nm

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