refraction of light Flashcards
refraction
the bending of light as it travels at an angle from one medium to a different medium
how does light travel in the same medium?
in a straight line and at a constant speed
what happens when light travels from one medium to another?
the light rays refract (“bend”)
fermat’s principle
when light travels from one point to another, it follows the path that will take the least time
in a single medium, the path that takes the least time is a straight line
refracted ray
ray that is bent upon entering a second medium
angle of refraction
the angle between the normal and a refracted ray
angle of incidence ___ angle of reflection
=
when does the light ray bend towards the normal?
a light ray travels from a medium in which its speed is faster (less dense medium) to a medium in which its speed is slower (denser medium)
when does the light ray bend away from the normal?
a light ray travels from a medium in which its speed is slower (denser medium) to a medium in which its speed is faster (less dense medium)
how much a light ray refracts is determined by _____________
the extent of the change in the speed of light as it travels from one medium to another
when light passes from one medium to the next and the change in the speed of light becomes greater (faster), the angle of refraction becomes ________
greater
index of refraction (n)
ratio of the speed of light in a vacuum divided by the speed of light in a given medium
what does the n stand for in n = c/v?
index of refraction
what does the c stand for in n = c/v?
speed of light in a vacuum
the speed of light in a vacuum
3 x 10 to the power of 8 m/s
what does the v stand for in n = c/v?
speed of light in a particular medium
why is the index of refraction always greater than 1?
the speed of light is always higher in a vacuum than in a medium
dispersion
the process of separating colours by refraction
each colour of light travels at ______________ in any medium
a slightly different speed
when do all the wavelengths of light and all the other forms of electromagnetic waves travel at the same speed (speed of light)?
only in a vacuum
when does partial reflection and refraction occur?
as light reaches a boundary between two media
in partial reflection and refraction, some light is reflected and some is refracted, but ___________
not equally
as the angle of incidence increases, more light will be _______ and less _________
reflected / refracted
critical angle
angle of incidence that produces an angle of refraction at 90 degrees and no light passes into the second medium
what does the critical angle depend on?
the optical densities of the 2 media
when does total internal reflection occur?
when the angle of incidence increases past the critical angle
how can total internal reflection occur?
light travels from a more dense medium (speed is lower) to a less dense medium (speed is higher)
the refracted ray angle increases more than the incident angle moving away from the normal towards the boundary of the two media
total internal reflection
eventually the refracted ray hits 90 degrees, the incident angle at which this occurs is called the __________
critical angle
total internal reflection
as the incident ray angle increases beyond the critical angle, the light no longer refracts because ___________
the refracted ray would no longer be in the second medium; all the light is reflected back into the first medium
for angles of incidence greater than the critical angle, _________ occurs
total internal reflection
what is the equation for the index of refraction (n)?
n = c/v
