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Optical Phenomenal Chapter 14 section 3

Optical Phenomenal

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Optical Phenomenal. Chapter 14 section 3 . Objectives . Predict whether light will be refracted or undergo total internal reflection. Recognize atmospheric conditions that cause refraction. - PowerPoint PPT Presentation

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Page 1: Optical Phenomenal

Optical PhenomenalChapter 14 section 3

Page 2: Optical Phenomenal

Objectives Predict whether light will be refracted or

undergo total internal reflection.

Recognize atmospheric conditions that cause refraction.

Explain dispersion and phenomena such as rainbows in terms of the relationship between the index of refraction and the wavelength.

Page 3: Optical Phenomenal

Total Internal Reflection Total internal reflection can occur when light

moves along a path from a medium with a higher index of refraction to one with a lower index of refraction.

At the critical angle, refracted light makes an angle of 90º with the normal.

Above the critical angle, total internal reflection occurs and light is completely reflected within

Page 4: Optical Phenomenal

Critical Angle Snell’s law can be used to find the

critical angle.

sin for

index of refraction of second mediumsine critical angleindex of refraction of first medium

rC i r

i

n n nn

•Total internal reflection occurs only if the index of refraction of the first medium is greater than the index of refraction of the second medium.

Page 5: Optical Phenomenal

Example Find the critical angle for a water-air

boundary if the index of refraction of water is 1.333

Page 6: Optical Phenomenal

Atmospheric Refraction Refracted light can create a mirage. What is a mirage? A mirage is an optical effect of the atmosphere caused by refraction

when light passes from air with one density into air with a different density and the object appears displaced from its true position.

The mirage called an inferior mirage occurs when the image appears below the true location of the observed object.

During a phenomenon called looming, objects sometimes appear to be suspended above the horizon.

Looming is considered a superior mirage because the image is seen above its true position.

A mirage that changes the apparent size of an object is called towering.

A type of towering, called Fata Morgana, is frequently observed in coastal areas as towering castles that appear out of thin air.

Page 7: Optical Phenomenal

Mirages A mirage is produced

by the bending of light rays in the atmosphere where there are large temperature differences between the ground and the air.

Page 8: Optical Phenomenal

Mirages

Page 9: Optical Phenomenal

Dispersion Dispersion is the process of separating

polychromatic light into its component wavelengths.

White light passed through a prism produces a visible spectrum through dispersion.

Page 10: Optical Phenomenal

Rainbows Perhaps the most spectacular and best known

atmospheric optical phenomenon is the rainbow. Sunlight and water droplets are necessary for the

formation of a rainbow. Furthermore, the observer must be between the Sun

and rain. When a rainbow forms, the water droplets act as

prisms and refraction disperses the sunlight into the spectrum of colors, a process called dispersion.

The curved shape of the rainbow results because the rainbow rays always travel toward the observer at an angle between 40 and 42° from the path of the sunlight.

Page 11: Optical Phenomenal

Rainbows

Page 12: Optical Phenomenal

Lens Aberration Chromatic aberration is the focusing

of different colors of light at different distances behind a lens.

Chromatic aberration occurs because the index of refraction varies for different wavelengths of light.

Page 13: Optical Phenomenal

Lens aberration

Page 14: Optical Phenomenal

Video Watch a video

Page 15: Optical Phenomenal

Go over lab Lets go over lab

Page 16: Optical Phenomenal

Homework Do problems 1-4 pg .502

Page 17: Optical Phenomenal

ClosureToday we learned about optical phenomenaNext class we are going to have a lab