Review on Ray Optics and Atmospheric Optics

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The Electromagnetic Spectrum

Lenses

-

8

-10

Convex

19

8

10 - 10 m in wavelength

10 - 10 Hz in frequency

EM waves emitted by radioactive nuclei - waves are

highly penetrating and cause serious damaged when

absorbed by living tissue. Astronomers observe strong gamma jets at the core of every blackhole and supergalactic nuclei.

Microwaves

X-rays

Concave

-7

14

10 - 10 m in wavelength

10 - 10 Hz in frequency

Most abundant lightsource produced by the sun,

Visible light is made by the rearrangement of electrons

in atoms and molecules. When electrons lower the energy level

They release a photon.

Visible

Principal axis

Infrared

-7

-9

-8

-12

18

15

Focal length

-6

-3

14

11

10 - 10 m in wavelength

10 - 10 Hz in frequency

Most of the UV light from the sun is absorbed by the upper atmosphere, however long term exposure to direct sunlight can be dangerous, as UV light can penetrate skin and change the molecular arrangement of DNA, causing cancer.

16

20

10 - 10 m in wavelength

10 - 10 Hz in frequency

Known as 'heat rays' IR waves are produced by hot objects and molecules, and can be easily absorbed by all materials. The IR energy absorbed by a substance agitates the atoms of the object, increasing

vibrational or translational energy

Radio

Ultraviolet

10 - 10 m in wavelength

10 - 10 Hz in frequency

Created by the acceleration of high energy electrons. X rays have the ability to probe the interatomic distances, and can be used to see how matter is structured.

-4

1

Gamma rays

12

9

-2

8

Focal point

10

0

10 - 10 m in wavelength

10 - 10 Hz in frequency

Microwaves are lightwaves with micron sized wavelengths. Microwaves are used in radar and aircraft systems, wavelengths small enough to study moelcular properties of matter. Microwave ovens and cellphones utilize EM radiation from this range.

10 - 10 m in wavelength

10 - 10 Hz in frequency

Radiowaves are the result of accelerating slow electron through conducting wires. Radiowaves are used in telecommunications and probing deep space

Ray Diagrams

1st ray runs parallel to the

principal axis, refracts towards

the focal point.

What is reflection?

2nd ray begins from obect,

runs straight towards the center of

the lens.

Light: Ray and Atmospheric

Optics Review

Angle of incidence = Angle of reflection

What is refraction?

Index of refraction

Why concave lenses?

c

n =

-

v

unitless ratio to

describe how much light slows down when entering a new medium

Object outside the focal length

n

Light bends away from the normal, when entering a lower indexof refraction

Light bends towards the normal,

when entering a higher index

of refraction

Real image (rays of light cross path)

Inverted (image upside down)

When object is inside the focal length

How is a rainbow formed?

d

How is the secondary bow formed?

Can you provide a ray diagram?

All parallel rays focus an image

at the focal point

As light enters the water droplet, it refracts toward normal

What causes the

Alexander's Dark band?

How is a mirage formed?

Virtual image formed (rays do not cross paths)

Upright image (above principal axis)

Internal reflection occurs, reversing

color of dispersing light

The Eye

Light strongly disperses as it

refracts outward,

bending away from normal

A real, inverted image is formed

Atmosphere acts like

lens, refracting light

towards the viewer

Light is a photon , both particle and wave.

Comprised of oscillating electric and magnetic fields

Speed of light c is constant (in vacuum)

c = 300,000,000 m/s or .3 Gm/s

Light follows wave speed equation:

Dispersion

Why is the Sky blue?

More Atmospheric Optics

Sundogs

Atmosphere acts like a double sided convex lens,

inverting a real image whose.

the index of refraction is temperature dependent,

inversion layers bend/refract light strongly

Blue light (shorter wavelength) is refracted at a greater angle than red light

Noctilucent clouds

Why are cones and rods useful?

How is light captured by the eye?

Speed of light

Wavelength

Frequency

Light pilars

Blindness vs. Corrective lenses

Fogbows

The earth's atmosphere is filled with minute dust and water particles that act like a filter, scattering the light rays. The rays of light with the longer wavelengths, such as reds and yellows, tend to pass more easily through the atmosphere, while the rays with the shorter wavelengths, like blues and indigos, tend to be randomly scattered more easily. These more easily dispersed shorter light rays are what give the sky its blue color.

Crepuscular Rays

Glory

inversely proportional