exam questions Flashcards
Give possible applications of the spectrometer & diffraction grating.
- (spectral) analysis of light from stars
- (analyse) composition of stars
- chemical analysis
- measuring red shift
Explain the meaning of the term monochromatic light.
single frequency
Describe how the pattern on a single slit screen would change if light of a longer wavelength was used.
the maxima are further apart and wider.
State two ways in which the appearance of the fringes would change if the slit was
made narrower. (single slit)
- wider fringes
- lower intensity
White light passes through a single narrow slit and illuminates a screen. What is observed?
a white central maximum surrounded by coloured fringes
What causes the separation of the maxima of the diffraction pattern to decrease? (diffraction grating)
using a grating with a greater slit separation
Explain what is meant by a progressive wave.
A wave transfers energy from one point to another
without transferring material
Describe how microwaves are used to demonstrate stationery waves.
- microwave source directed at reflective metal surface
- probe detector picks up antinodes and nodes
Describe the apparatus to show how sound waves can produce stationery waves.
→ 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
Explain what frequencies would be produced for larger tensions in an investigation of vibrations in a
stretched nylon string.
- diameter reduced when string is stretched
- lower mass per unit length
- frequency is higher
Explain the graph for spring immersed in oil.
Describe the pattern produced on a fluorescent screen when electrons are incident on it and they behave as a stream of particles.
only produce a small patch of light as particles are scattered randomly.
State one application of optical fibres.
endoscopes
State and explain one reason why the core of an optical fibre is made as narrow as possible.
→ to reduce multimode dispersion
→ causes light travelling at different angles to arrive at different times (pulse broadening)
State how each of speed, frequency and wavelength changes, if at all, when light travels from air to
glass.
speed → decreases
frequency → stays constant
wavelength → decreases
