Optics Flashcards
What is a normal
90 degrees to surface
Which way does light bend when moving air to glass
Towards the normal
Which way does light bend as it goes glass to air
Away from the normal
Which way does light bend when going to a more dense substance
Towards normal
Which way does light bend when it passes into less dense substance
Away from the normal
What law tells you the ratio of refractive index
Snells law
Equation of refractive index
Sine of angle of incidence /sine of angle of refraction (n=sin i /sin r)
Why does refraction occur
As the speed of light is different in different substances
How does speed of light relate to angle of incidence and refraction
Sin i /sin r = c/c
How does speed of light relate to wavelength
C1/C2= wavelength 1/wavelength 2
Refractive index between 2 substances
N1sinx1=n2sinx2
How can we split a beam of white light
Using a glass prism
Approximate wavelength of red light
650nm
Approximate wavelength of violet light
350nm
Why does the white light spectrum work
As violet slows down more that red light causing the light to spread out more.
Total internal reflection
When the light wave refracts through a barrier and moves along a boundary
What makes the curved edge of a semi Circe interesting
As all light directed at it is at 90 degrees to the surface
What must be present for total internal reflection to occur
Large refractive index compared to other substances
The angle of incidence exceeds the critical angle
Uses of optical fibres
Medical endoscopes
Communication
What is the composition of a fibre optic
Glass core and cladding
What’s the reason for cladding on fibre optic
To make it possible to run many strands next to each other
Why are optical fibre cores narrow
To prevent modal dispersion
What is modal dispersion
When some light waves take a longer route through a fibre compared to others
Why is modal dispersion not wanted
Can lead to data being spread,jumbled and becoming unusable
