exam questions Flashcards

1
Q

Give possible applications of the spectrometer & diffraction grating.

A
  • (spectral) analysis of light from stars
  • (analyse) composition of stars
  • chemical analysis
  • measuring red shift
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2
Q

Explain the meaning of the term monochromatic light.

A

single frequency

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3
Q

Describe how the pattern on a single slit screen would change if light of a longer wavelength was used.

A

the maxima are further apart and wider.

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4
Q

State two ways in which the appearance of the fringes would change if the slit was
made narrower. (single slit)

A
  • wider fringes
  • lower intensity
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5
Q

White light passes through a single narrow slit and illuminates a screen. What is observed?

A

a white central maximum surrounded by coloured fringes

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6
Q

What causes the separation of the maxima of the diffraction pattern to decrease? (diffraction grating)

A

using a grating with a greater slit separation

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7
Q

Explain what is meant by a progressive wave.

A

A wave transfers energy from one point to another
without transferring material

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8
Q

Describe how microwaves are used to demonstrate stationery waves.

A
  • microwave source directed at reflective metal surface
  • probe detector picks up antinodes and nodes
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9
Q

Describe the apparatus to show how sound waves can produce stationery waves.

A

→ heaps of dry powder placed in glass tube/air column
→ a loudspeaker is placed at the open end
→ powder is shaken away at antinodes & left undisturbed at nodes

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10
Q

Explain what frequencies would be produced for larger tensions in an investigation of vibrations in a
stretched nylon string.

A
  • diameter reduced when string is stretched
  • lower mass per unit length
  • frequency is higher
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11
Q

Explain the graph for spring immersed in oil.

A
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12
Q

Describe the pattern produced on a fluorescent screen when electrons are incident on it and they behave as a stream of particles.

A

only produce a small patch of light as particles are scattered randomly.

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13
Q

State one application of optical fibres.

A

endoscopes

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14
Q

State and explain one reason why the core of an optical fibre is made as narrow as possible.

A

→ to reduce multimode dispersion
→ causes light travelling at different angles to arrive at different times (pulse broadening)

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15
Q

State how each of speed, frequency and wavelength changes, if at all, when light travels from air to
glass.

A

speed → decreases
frequency → stays constant
wavelength → decreases

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16
Q

explain why the amplitude of a pulse at the end of a fibre may be less than its initial amplitude.

A

energy loss within the fibre

17
Q

State two differences in the appearance of the pattern obtained with a laser and that
produced by a white light source such as a candle

A

→ white light contains central white fringe with rainbow outer fringes
→ maxima further apart for a red laser