2.2 Optics Flashcards
What happens to the angle of light after it enters a denser medium (a higher refractive index)?
The angle is reduced
What happens to a light ray if the angle of incidence equals the critical angle?
The light will emerge along the boundry between the 2 materials
If you increase the refractive index, what happens to the critical angle?
It gets smaller
What happens when the angle of incidence is greater than the critical angle?
The light ray is totally internally reflected
What are the 2 conditions for total internal reflection
- The incident angle must be greater than the critical angle
- The light must be moving from a larger refractive index to a lower refractive index
Why do optical fibres have cladding around them?
So the light is likely to be totally internally reflected and to protect the cores from breaking or losing data being sent along them
What is multipath dispertion?
Where the core of fibre optic cables is too wide so when some light is reflected, other rays aren’t meaning the data reaches the computer at diffrent times making it corrupt.
What is spectral dispersion?
Where white light is sent through fibre optic cables meaning the colours are dispersed and will corrupt data, therefore monochromatic light is used
What is seen as a result of Young’s double slit experiment?
Fringes of light and dark where the light is interfering with another source of light causing constructive and destructive interference
What does W represent in the double slit equation?
The fringe seperation, the distance between the centre maxima and the next maxima
What does s represent in the double slit equation?
The slit spacing, the distance between the centre of the double slits
Define coherent sources
Sources with the same frequency and a constant phase difference
What is the diffrences between monochromatic interference patterns and white light interference patterns?
Monochromatic light sources: One colour More intense Narrower maxima Fringes on dots White light sources: Contains all colours with a single white central maxima Less intense Wider maxima Fringes in lines
What does d represent and how is it calculated in the diffraction grating equation?
The grating spacing, the distance between adjacent slits. It is found 1/the number of slits per metre
What effect will increasing the number of slits have on the interference pattern shown on the screen?
The maximas will have larger gaps between them
