Optical phenomena

Chapter 14-Refraction

Section 3: Optical phenomena

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 wavelength.

Open Ended

Describe what you see in the picture.

Open Ended

Describe what you see in the picture.

Open Ended

Define critical angle Θ_c .

Open Ended

Based on the picture you see, try to define total internal reflection.

Open Ended

Based on what we discussed earlier, list the conditions for total internal reflection to occur.

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.

higher index means denser medium (speed slower)

• 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 a substance.

Total Internal Reflection

Atmospheric Refraction

• The mirage is another phenomenon of nature

produced by refraction in the atmosphere

• Refracted light can create a mirage.

• 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.

The sun can be seen even after it has passed below the
horizon. Rays of light from the sun strike Earth’s
atmosphere and are bent because the atmosphere has
an index of refraction different from that of the near-
vacuum atmosphere of space. Our eyes follow them
back along the direction from which they appear to have
come.

Snell's Law for total internal

Multiple Choice

The critical angle is defined as the angle of incidence at which the total internal reflection starts to occur.

• True

• False

Multiple Choice

The angle of incidence is equal to the angle of reflection for perfect reflection.

• True

• False

Multiple Choice

For a critical angle of 60 degree and the refractive index of the first medium is 1.732, the refractive index of the second medium isa) 1b) 1.5c) 2d) 1.66

• 1

• 1.5

• 2

• 1.66

Open Ended

Describe the phenomenon that you see in the picture.

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.

The blue light is bent more that the red light and then the spectrum that we see starts from high wavelength to low wavelength

Give one application for dispersion of light.

Rainbows
https://www.youtube.com/watch?v=lUjvmgDaKCs

https://www.youtube.com/watch?v=q73VNpFA-0Q

Open Ended

What is atmospheric refraction?

Open Ended

Try to search for the optical phenomenom seen in the picture.

Describe what you see.

Open Ended

Describe what you see in the picture.

Open Ended

Based on the picture you see, how do we correct chromatic aberration?

Lens Aberrations

• 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.

• Chromatic aberration can be greatly

reduced by the use of a combination of
converging and diverging lenses made
from two different types of glass.

https://www.youtube.com/watch?v=EL9J3Km6wxI