Reflection and refraction Flashcards
the normal
a line drawn at 90 degrees to the mirror surface at the point that the arriving/incident ray meets the mirror
angles r and i are measured from this line
angle i and r
angle of incidence (between the incident ray and the normal)
angle of reflection/refraction (between the reflected ray and the normal)
incident ray and reflected ray
the ray of light that meets the mirror/substance
the reflected ray of light
law of reflection
angle i = angle r
refraction
change in direction of a light ray when it travels from one transparent material into another
Describe the effect of density on light rays in regards to the angle of incidence and reflection and wave speed
when light enters a more dense substance it bends towards the normal and slows down
when light enters a less dense substance it bends away from the normal and speeds up
What happens if a ray of light meets a material at 90 degrees?
nothing, it travels along the normal so the direction doesn’t change
Why does refraction happen?
because light waves travel at different directions at different speeds in different materials
State the law of reflection [1]
the angle of incidence is equal to the angle of reflection
Explain what happens during refraction [3]
the speed of the wave changes as it moves from one medium to another
its direction also changes unless it is travelling along the normal
A ray of light strikes a plane mirror at 42 degrees to the normal.
State the angle of reflection [1]
42 degrees
A ray of light is travelling through a glass block before entering into air. The angle of incidence in the glass block is 34 degrees.
Estimate the angle of refraction once it has entered the air and give a reason [2]
greater than 34 as it speeds up and bends away from the normal
(e.g. 45 degrees)
State the factors that influence the angle of refraction for a material [2]
the ratio of refractive indices wither side of the boundary
the optical density of the material
material and speed of waves in different materials
Describe how each of these change during refraction:
a) wave speed [2]
b) wavelength [2]
c) frequency [1]
a) speeds up when moving from more to less dense medium
b) decreases when moving from less dense to more dense material
c) no change