Resource Lesson
Snell's Law
Printer Friendly Version
To determine the degree to which a light ray bends as it obliquely transitions from one medium to another, we will use our knowledge of refraction and Snell's Law. For those interested in seeing a derivation of Snell's Law, please reference this
accompanying lesson
.
n
_{1}
sin θ
_{1}
= n
_{2}
sin θ
_{2}
where
n
_{1}
is the
index of refraction
for the first medium
n
_{2}
is the index of refraction for the second medium
that angles θ
_{1}
and θ
_{2}
are always measured from the normal, NEVER from the interface.
Here is a list of common indices for the 589 nm wavelength in
sodium's spectrum
.
medium
index
medium
index
vacuum
1.00000
fused quartz
1.46
air (STP)
1.00029
crown glass
1.52
water (20ºC)
1.33
polystyrene
1.55
acetone
1.36
carbon disulfide
1.63
ethyl alcohol
1.36
flint glass (heavy)
1.65
sugar solution (30%)
1.38
sapphire
1.77
sugar solution (80%)
1.49
diamond
2.42
If n
_{2}
> n
_{1}
, then the light is entering an optically more dense medium and the ray will bend "towards the normal" as it enters n
_{2}
.
This phenomena occurs because the
wavelength shortens in the second medium
resulting in the light having a slower average velocity.
Note that the ray bends towards the normal as the light enters the glass and that θ
_{glass}
is smaller than θ
_{air}
.
If n
_{2}
< n
_{1}
, then the light is entering an optically less dense medium and the ray bends "away from the normal" when it enters n
_{2}
.
This phenomena occurs because the wavelength lengthens in the second medium resulting in the light having a faster average velocity.
Note that the ray bends away from the normal as the light exits the glass as it returns into the air and that θ
_{air}
is greater than θ
_{glass}
.
Refer to the following information for the next question.
If a ray of light strikes the top surface of a dish of water at an angle of 37º to the vertical, at what angle will it be refracted as it enters the water?
Refer to the following information for the next six questions.
Suppose a ray of light enters a glass slab (n = 1.56) that is covered with water (n = 1.33) as shown in the diagram below. Each layer is 10 mm thick and the initial angle of incidence equals 30º. Our goal in the following series of questions is to determine the beam's linear displacement, X, from its initial straight-line path when it emerges from the bottom of the glass.
At what angle does the ray enter the water?
What is the value for x
_{1}
in the diagram shown in the hint?
At what angle does the ray enter the glass?
What is the value for x
_{2}
in the diagram shown in the hint?
What is the value for x
_{3}
in the diagram shown in the hint?
What is the value for X?
Related Documents
Lab:
Labs -
A Simple Microscope
Labs -
Blank Ray Diagrams for Converging Lenses
Labs -
Blank Ray Diagrams for Converging, Concave, Mirrors
Labs -
Blank Ray Diagrams for Diverging Lenses
Labs -
Blank Ray Diagrams for Diverging, Convex, Mirrors
Labs -
Determining the Focal Length of a Converging Lens
Labs -
Index of Refraction: Glass
Labs -
Index of Refraction: Water
Labs -
Least Time Activity
Labs -
Man and the Mirror
Labs -
Man and the Mirror: Sample Ray Diagram
Labs -
Ray Diagrams for Converging Lenses
Labs -
Ray Diagrams for Converging Mirrors
Labs -
Ray Diagrams for Diverging Lenses
Labs -
Ray Diagrams for Diverging Mirrors
Labs -
Reflections of a Triangle
Labs -
Spherical Mirror Lab
Labs -
Student Lens Lab
Labs -
Target Practice - Revised
Resource Lesson:
RL -
A Derivation of Snell's Law
RL -
Converging Lens Examples
RL -
Converging Lenses
RL -
Demonstration: Infinite Images
RL -
Demonstration: Real Images
RL -
Demonstration: Virtual Images
RL -
Dispersion
RL -
Diverging Lenses
RL -
Double Lens Systems
RL -
Lensmaker Equation
RL -
Mirror Equation
RL -
Properties of Plane Mirrors
RL -
Refraction of Light
RL -
Refraction Phenomena
RL -
Snell's Law: Derivation
RL -
Spherical Mirrors
RL -
Thin Lens Equation
Review:
REV -
Drill: Reflection and Mirrors
REV -
Mirror Properties
REV -
Physics I Honors: 2nd 9-week notebook
REV -
Physics I: 2nd 9-week notebook
REV -
Spherical Lens Properties
Worksheet:
APP -
Enlightened
APP -
Reflections
APP -
The Librarian
APP -
The Starlet
CP -
Lenses
CP -
Plane Mirror Reflections
CP -
Refraction of Light
CP -
Snell's Law
CP -
Snell's Law
NT -
Image Distances
NT -
Laser Fishing
NT -
Mirror Height
NT -
Mirror Length
NT -
Reflection
NT -
Underwater Vision
WS -
An Extension of Snell's Law
WS -
Basic Principles of Refraction
WS -
Converging Lens Vocabulary
WS -
Diverging Lens Vocabulary
WS -
Lensmaker Equation
WS -
Plane Mirror Reflections
WS -
Refraction and Critical Angles
WS -
Refraction Phenomena
WS -
Refraction Through a Circular Disk
WS -
Refraction Through a Glass Plate
WS -
Refraction Through a Triangle
WS -
Snell's Law Calculations
WS -
Spherical Mirror Equation #1
WS -
Spherical Mirror Equation #2
WS -
Spherical Mirrors: Image Patterns
WS -
Thin Lens Equation #1: Converging Lenses
WS -
Thin Lens Equation #2: Converging Lenses
WS -
Thin Lens Equation #3: Both Types
WS -
Thin Lens Equation #4: Both Types
WS -
Two-Lens Worksheet
WS -
Two-Mirror Worksheet
TB -
27B: Properties of Light and Refraction
TB -
Refraction Phenomena Reading Questions
PhysicsLAB
Copyright © 1997-2020
Catharine H. Colwell
All rights reserved.
Application Programmer
Mark Acton