Waves Flashcards
How should you draw the wavelength on a diagram of a wave
Lines/arrows at both ends to show when it stops
A light source is 1.5 m below the water and shines in all directions. How do you find the diameter of the disc through which light emerges from the water
The light only emerges from the water if TIR does not occur. Therefore you are finding the distance across the water from when TIR happens to the left and the right of the light source
How does a longer wavelength affect the appearance of the interference pattern
The maxima become wider (maxima, not the interference pattern)
Subsidiary maxima are spectrum of colours
What is the purpose of the core
Transmission medium for the light to progress by TIR
What is the relationship between wave speed and refractive index
Increased refractive index means the light is slower as n = C/Cs and Cs is decreasing for n to get bigger
What are 2 ways of reducing material dispersion
monochromatic light
monomode fibre
How is a standing wave formed
reflection causing 2 progressive waves travel in opposite directions and meet, leading to superposition
(you have to say they meet and don’t say superimpose)
How do you draw, on a graph, the intensity of light reaching observer as a polarising filter is turned 360 degrees
- Imagine it starts at Maximum
- Go down to minimum at 90
- Maximum at 180
- Minimum at 270
- Maximum at 360
(the lines curve around the maximum intensity a bit, so not a fully straight line
Why should the single slit be narrow
So more diffraction at the single slit so the double slits are both illuminated
How are amplitude and energy related, how is this shown in a microwave?
Directly proportional, so most energy at the antinodes and least at the nodes
Microwave without turntable would only heat the antinodes. This is why a turntable is used to change the position of antinodes constantly
How can you get a more accurate result for wavelength in young’s double slit experiment
Measure across more maxima and divide
Use a large D value to increase fringe width so it is easier to measure
describe the motion of a point on a stationary wave
Oscillates up and down about the equilibria position with a constant amplitude
What is the time period of a stationary wave
Time taken for a point to move down and up back to where it started
What is the advantage of using a narrower core
Less multipath dispersion so less signal degradation so BETTER QUALITY SIGNAL
Describe why a diffraction grating is a better image
Its brighter
Its sharper
The angles between fringes are larger
