Refraction - (Physics 3)

refraction

the bending of light as it travels from one medium to another

if light travels from one transparent medium to another at any angle other than straight on,

the light ray changes direction when it meets the boundary

the angle between the refracted ray and the normal is called

the angle of refraction, θ_r

the angle of incidence is designated as

θ_i

examples of transparent media through which light can pass

glass, water, ice, diamonds, and quartz

the speed of light in water is less than

the speed of light in air

the speed of light in glass is less than

the speed of light in water

if a ray moves from a material in which its speed is lower to one in which its speed is higher,

the ray is bent away from the normal

the normal

the imaginary line drawn perpendicular (90 degrees) to the surface at the point where light enters or exits a new medium

if the incident ray of light is parallel to the normal,

then no refraction (bending) occurs in either case

the path of a light ray that crosses a boundary between two different media is

reversible

index of refraction

the ratio of the speed of light in a vacuum to the speed of light in a given transparent medium

the index of refraction for a substance is the ratio of

the speed of light in a vacuum to the speed of light in that substance

light ray

the direction of propagation of the wave is perpendicular to the wave front

the frequency of light does not change when

the light passes from one medium to another

index of refraction formula

n = c/v

index of refraction = speed of light in vacuum/speed of light in medium

the index of refraction is a

dimensionless number that is always greater than 1 (because light always travels slower in a substance than in a vacuum)

the larger the index of refraction is,

the slower light travels in that substance and the more a light ray will bend when it passes from a vacuum into that material

when light passes from the water to the air,

the light rays are bent away from the normal

(for air) n =

1.00

the amount of light bends when entering a different medium depends on

the wavelength of light as well as the speed

since each color of light has a different wavelength,

each color of the spectrum is refracted by a different amount

snell’s law

a way to find either the angle of incidence or the angle of refraction

( how the light bends when passing from one medium to another )

snell’s law formula

n_1 sine(θ_1) = n_r sine(θ_r)

the index of refraction of a material can be used to figure out

how much a ray of light will be refracted as it passes from one medium to another

the greater the index of refraction,

the more refraction occurs

speed of light ( c )

3 × 10^8 m/s

calculate the speed of light in any material

v = c/n