5.1- REFRACTION OF LIGHT Flashcards
What theory can be used to explain reflection and refraction of light?
wave theory
When we consider the effect of lenses or mirrors on the path of light, what do we usually prefer to draw diagrams using?
light rays and normals
What do light rays represent?
direction of travel of wavefronts
What is the normal?
imaginary line perpendicular to a boundary between to materials or a surface
What is refraction?
change of direction that occurs when light passes at an angle across a boundary between two transparent substances
Where would light ray bend towards when it passes from air into glass?
towards normal when it passes from air into glass
Where would light ray bend towards when it passes from glass into air?
away from normal when it passes from glass to air
When does no refraction take place?
if the incident light ray is along the normal
At boundary between two transparent substances, where does light ray bend towards when it passes into more dense substance?
towards normal if it passes into a more dense substance
At boundary between two transparent substances, where does light ray bend towards when it passes into less dense substance?
away from normal if it passes into a less dense substance
Investigating the refraction of light by glass method?
use ray box to direct light ray into rectangular glass block at different angles of incidence at midpoint P of one of the longer sides
What is the angle of incidence?
angle between incident light ray and normal at point of incidence
What is the angle of refraction?
angle between the normal and refracted ray
What does the measurements of the angles of incidence and refraction for different incident rays show? (2) (investigating the refraction of light by glass)
angle of refraction at P always less than angle of incidence
ratio of sin i / sin r same for each light ray
What is the ratio of sin i / sin r known as?
Snell’s law
What is the ratio sin i / sin r referred to as?
refractive index
For light ray travelling from air into transparent substance, how is the refractive index of the substance worked out?
sin i / sin r
What else occurs when a light ray in air enters glass (or any other refractive substance)?
partial reflection
Why would the angle of refraction of light ray emerging from block be same as angle of incidence of light ray entering block?
two sides of block at which refraction occurs are parallel to each other
Refraction of light ray by triangular prism
light ray refracts towards normal where it enters glass prism then refracts away from normal where it leaves prism
