# Application of reflected and refracted light #### Everything You Need in One Place

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##### Intros
###### Lessons
1. Application of Reflected and Refracted Light
2. Introduction to total internal reflection
3. The condition of total internal reflection, critical angle
##### Examples
###### Lessons
1. Total Internal Reflection
Calculate the critical angle of the following materials
1. Glass with refractive index of 1.54
2. Ice with refractive index of 1.31
1. A beam of light is refracted by a type of glass as shown below
Angle of incidence: 30°
Angle of refraction: 22° 1. Calculate the refractive index of this type of glass.
2. Calculate the critical angle of the glass.
1. A ray of light enters a glass prism with a refractive index of 1.50, as shown below; 1. Explain what happens as the ray enters the prism
2. Find the value of angle X
3. Explains what happens as the ray reaches point O
###### Topic Notes

In this lesson, we will learn:

• The total internal reflection conditions
• Solving problems on total internal reflation
• Formation of Mirage
• Dispersion of light
• The use of optical fibers

Notes:

• Total Internal Reflection:

Complete reflection, there is NO refraction
It occurs under the following circumstances:

1. The ray of light travels from a more optically dense medium to a less optically dense medium.
2. The angle of incidence is greater than a certain limiting angle (the critical angle).

• Critical Angle

The incident angle that causes the refracted ray to lie right along the boundary of the substance, angle $\theta _{c}$, is it unique to the substance.

In other words;
The measure of angle of incidence when angle refraction is 90°
OR
The measure of angle of incidence when the refracted ray grazes the boundary.

< $r$ = 90° $\Rightarrow$ <$i$ = < $\theta _{c} \qquad$ Reflection and Refraction • The angle of incidence is greater than the critical angle; the ray of light is totally reflected, No refraction • The angle of incidence is smaller than the critical angle; the ray of light gets both reflected and refracted. • Effect of refraction and reflection: Mirage, Dispersion of light, and Optical fiber

• Mirage:
An optical effect that is seen above the hot road, the road looks like a pool or mirror due to the total internal reflection of light.
The layers of air above the ground are colder and less dense
Layers at the surface of the ground are hotter and denser
As light travels from less dense to denser layer with an angle of incidence greater than the critical angle, it gets totally reflected, no refraction Dispersion of light: White light directed thorough a prism is dispersed into bands of different colors.
Example: Rainbow, it is the dispersion of sun light through water droplets. • Optical Fiber: It is a long thin flexible sample of a transparent medium. Any light ray entering the optical fiber will remain trapped inside, even if the fiber is bent.
The total internal reflection occurs.
Light energy stays the same throughout the fibers.
• Use of optical fibers
1. Surgical tools to treat illness, without deterioration of image quality
2. Telecommunication, to transfer video and audio information with no loss of signals. 