# Define Critical Angle and Explain Total Internal Reflection. What Are the Conditions Necessary for Total Internal Reflection? - Physics

Short Note
Define critical angle and explain total internal reflection. What are the conditions necessary for total internal reflection?

#### Solution

Critical angle: The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90o.
Total internal reflection: It is an optical phenomenon that occurs when a ray of light strikes the boundary of denser medium at an angle greater than the critical angle w.r.t. the normal of the surface; this ray is then totally reflected back into the denser medium.
The two necessary conditions for total internal reflection to take place are:
1.The light ray must proceed from denser to rarer medium.
2. Angle of incidence in denser medium should be greater than the critical angle for the pair of media in contact.

Is there an error in this question or solution?

#### APPEARS IN

Frank ICSE Class 10 Physics Part 2
Chapter 2 Light
Exercise | Q 1 | Page 117