Application
of
Refraction
Laws of refraction
Snell’s Law
Index of refraction
Critical Angle and Total Internal Reflection
Lenses and Application
Lens Equations
Ray Diagram for Lenses
Reflection
Definition: bouncing back of light rays after hitting a surface.
Incident ray - The ray of light falling on the surface.
Normal
reflected
ray
incident
ray
Reflected ray - The Incident ray bouncing
back In the same medium after striking the
reflecting surface.
Normal - It is the line drawn perpendicular to
the reflecting surface at the point of incidence.
i
r
mirror
Angle of Incidence - The angle formed
between the incident ray and the normal.
Angle of reflection - The angle formed between
the normal and the reflected ray.
Law of Reflection
1. The incident ray, the reflected ray and the normal
ray at the point of incidence, all lie in the same
plane.
2. The angle of incidence is equal to the angle
of reflection.
Incident
ray
Reflected
ray
Refraction of Light
→ Bending of light
i > r
air
i
r
glass
Law of Refraction
Snell’s Law:
1. The incident ray refracted
ray, and the normal to the
interface of two media at the
point of incidence all lie on
the same plane.
2. The ratio of the sine of the
angle of incidence to the sine
of the angle of refraction is a
constant.
air
i
r
glass
sin 𝑖
sin 𝑟
= 𝑐𝑜𝑛𝑠𝑡𝑎𝑛𝑡
Snell’s Law
The refractive index is related to
the speed of light in the material
(which is less than its speed in a
vacuum):
i. A ray of light from car 1 is shown.
On the diagram, clearly draw the normal to the
plane mirror where this ray
hits the plane mirror. Label the normal N.
ii. On the diagram, carefully draw the reflected ray
of light.
iii. State the law used in your answer to (a)(ii).
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iv. Can each driver see the other car? Explain your
answer.
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Explain why the ray does not change
direction as it enters the plastic block.
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