Physics Chapter 14 Study Guide
Refraction

Christiaan Huygen (1629 - 1695) - Dutch mathematician, astronomer, and physicist

huygens

 

Refraction

Refraction – the bending of a wave front as the wave front passes between two substances in which the speed of the wave differs or the bending of a wave disturbance as it passes at an angle from one medium into another

 

Some examples of refraction

refraction of light

 

refraction

 

Java Applet for Refraction

 

Why does refraction happen?

refraction

 

refraction

 

Law of Refraction

Index of Refraction – the ratio of the speed of light in a vacuum to the speed of light in a given transparent medium.

index of refraction

 

Indices of Refraction for Various Substances

Solids at 20˚C
n
Liquids at 20˚C
n
Cubic zirconia
2.20
Benzene
1.501
Diamond
2.419
Carbon disulfide
1.628
Fluorite
1.434
Carbon tetrachloride
1.461
Fused quartz
1.458
Ethyl alcohol
1.361
Glass, crown
1.52
Glycerine
1.473
Glass, flint
1.66
Water
1.333
Ice (at 0˚C)
1.309
   
Polystyrene
1.49
Gases at 0˚C, 1 atm
n
Sodium chloride
1.544
Air
1.000293
Zircon
1.923
Carbon dioxide
1.000450

 

Applications of Refraction

cat and fish

 

fish and cat

 

Snell's Law

Snell's Law

snell's law

 

Example 1

A light beam in air hits a sheet of crown glass at an angle of 30.0˚. At what angle is the light beam refracted?

 

 

 

 

 

 

 

 

 

Example 2

A laser beam in air is incident upon ethanol at an angle of incidence of 37.0˚. What is the angle of refraction?

 

 

 

 

 

 

 

Example 3

A block of unknown material is submerged in water. Light in the water is incident on the block at an angle of incidence of 31˚. The angle of refraction of the light in the block is 27˚. What is the index of refraction of the material of the block?

 

 

 

 

 

 

 

 

Thin Lens

Lens – a transparent object that refracts light rays, causing them to converge or diverge to create an image

 

Ray Diagrams for Lenses

Convex Lenses

ray diagram 1

 

 

ray diagram 2

 

 

ray diagram 3

 

 

ray diagram 4

 

 

ray diagram 5

 

 

ray diagram 6

 

Concave Lenses

ray diagram 7

 

 

Thin Lens Equation

 

lens equation

 

Magnification Equation

magnification equation

 

Example 4

An object is placed 32.0 cm from a convex lens that has a focal length of 8.0 cm.

a. Where is the image?

 

 

 

 

b. If the object is 3.0 cm high, how tall is the image?

 

 

 

 

c. What is the orientation of the image?

 

 

 

 

 

Corrective Lenses for Nearsightedness

nearsightedness

 

Corrective Lenses for Farsightedness

farsightedness

 

 

Combination of Thin Lenses

Compound Microscopes

microscope

 

 

Refracting Telescopes

telescope

 

 

Example 5

Two converging lenses are placed 20.0 cm apart, as shown in the figure. If the first lens has a focal length of 10.0 cm and the second has a focal length of 20.0 cm, locate the final image formed of an object 30.0 cm in front of the first lens. Find the magnification of the system.

problem figure

 

 

 

 

 

Answer Figure

problem answer

 

 

Optical Phenomenon

dispersion

 

Total Internal Reflection

Total Internal Reflection–the complete reflection of light at the boundary of two transparent media; this effect occurs when the angle of incidence exceeds the critical angle.

Critical Angle–the minimum angle of incidence for which total internal reflection occurs

total internal reflection

 

Calculating a Critical Angle

critical angle

critical angle

 

Example 6

What is the critical angle for light emerging from carbon disulide into air?

 

 

 

 

 

 

 

 

 

Example 7

One method of determining the refractive index of a transparent solid is to measure the critical angle when the solid is in air. If the critical angle is found to be 40.5˚, what is the index of refraction of the solid?

 

 

 

 

 

 

 

 

Application of Internal Reflection

fiber optics

 

 

 

Dispersion

Dispersion–the process of separating polychromatic light into its component wavelength

 

dispersion

 

Rainbows

rainbow

 

Double Rainbow

double rainbow

double rainbow

 

 

Mirages

inferior mirage

 

inferior mirage

 

superior mirage

superior mirage

 

Chromatic Aberration

Chromatic Aberration–the focusing of different colors of light at different distances behind a lens

chromatic aberation

correcting chromatic aberation