Reflection & Refraction Of light

By: Ahmed

Definitions

Luminous objects – generate their own light (the sun)

Illuminated objects – reflect light (the moon)

Definitions

Line of Sight – a line from an object or image to your eyes (light from the object travels along this line to your eyes)

Rays of Light

Incident Ray – leaves the object and strikes the mirror

Reflected Ray – leaves mirror and strikes your eye

The reflected ray is on the line of sight from the image to your eye.

Law of Reflection

Angle of incidence equals angle of reflection.

Law of Reflection

Normal – line perpendicular to the mirror surface

Angle of incidence – angle between incident ray and normal

Angle of reflection – angle between reflected ray and normal

Diffuse Reflection

Diffuse Reflection

RefractionThe change in direction of a wave as is

crosses the boundary between two media in which the wave travels at different speeds.

Snell’s Law

2211 sinsin nn

Problem 1

Substance Index of RefractionAir (vacuum) 1.00Water 1.33Alcohol 1.36Quartz 1.46Lucite 1.50Benzene 1.50Glass – Crown 1.52Plexiglas 1.55Glass – Flint 1.61Diamond 2.42

A ray of light in air is approaching theboundary with water at an angle of 52 degrees. Determine the angle of refraction of the light ray. Refer to the table of indices of refraction if necessary.

Answer 1

Given:ni = 1.00 (from table)nr =

1.333 (from table)Θi = 52 degrees

Find:

• Θr =??

Problem 2

A ray of light in air is approaching the boundary with a layer of crown glass at an angle of 42.0 degrees. Determine the angle of refraction of the light ray upon entering the crown glass and upon leaving the crown glass. 

Answer 2

Given:Boundary #1

ni = 1.00 (from table)

nr = 1.52 (from table)

Θi = 42.0 degreesBoundary #2

ni = 1.52 (from table)

nr = 1.00 (from table)

Find: Θr atboundary #1

and Θr at boundary #2

Worksheet