Refraction Flashcards
what is refraction?
the fact or phenomenon of light, radio waves, etc. being deflected in passing obliquely through the interface between one medium and another or through a medium of varying density
when light goes from less dense to more dense…
it SLOWS down and bends TOWARDS the normal
when light goes from more dense to less dense…
it SPEEDS up and bends AWAY from the normal
the wavelength changes the changes, what happens to the frequency?
it stays the same
when does dispersion occur?
a prism splits the colours of white light into the spectrum
why dispersion occur?
the refractive index of the glass or perspex of the prism varies with the colours of the spectrum that make up white light
what colour has the greatest refractive index and deviates the most?
violet
what colour has the lowest refractive index and deviates the least?
red
what is the critical angle?
angle of incidence that produces an angle of refraction of 90 degrees
if the angle of incidence is LESS than the critical angle so the ray is…
refracted with a very small reflection
if the angle of incidence is EQUAL to the critical angle so the ray is…
emerges along the edge of the block
if the angle of incidence is GREATER than the critical angle so the ray is…
totally internally reflected
what is total internal reflection?
- light going from MORE to LESS dense
- at an angle bigger than the CRITICAL ANGLE…
- is ALL reflected
- from the INSIDE SURFACE
what does total internal reflection allow?
light signals to be transmitted down glass fibres as an alternative to electrons moving in conductors
what has the introduction of optical fibres been totally dependent on?
the ability of manufacturers to produce very thin fibres of highly transparent glass
what are optical fibres?
a thin rod of high-quality glass
advantage #1 of optical fibre over copper wire?
has a higher bandwidth and therefore can carry more information
advantage #2 of optical fibre over copper wire?
less attenuation of signal over distance
advantage #3 of optical fibre over copper wire?
not prone to electromagnetic interference
advantage #4 of optical fibre over copper wire?
signal is less likely to be intercepted / read by third parties since it does not emit EMR signal
disadvantage of optical fibre
connecting two optical fibres is more complicated
what is diffraction?
the process by which a beam of light or other system of waves is spread out as a result of passing through a narrow aperture or across an edge
what is reflection?
the change in direction of a wavefront at an interface between two different media so that the wavefront returns into the medium from which it originated
what is refraction?
the change in direction of a wave passing from one medium to another medium caused by its change in speed.
what is the angle of incidence?
the angle between the normal and the ray of light
what is the normal?
an imaginary line perpendicular to the surface reflecting the light
