Total Internal Reflection Questions

We learned about light as the form of energy in our previous sessions. We also know that light exhibits particle as well as wave nature. It also undergoes various phenomena like refraction, reflection, diffraction, and total internal reflection.

The phenomenon of total internal reflection takes place at the boundary between two transparent media when a light ray in a medium of higher index of refraction approaches the other medium at an angle of incidence greater than the critical angle. In simple words total internal reflection is the phenomenon that takes place when the light rays travel from a more optically denser medium to a less optically denser medium. Total internal reflection takes place in electromagnetic waves, light waves, microwaves, sound waves as well as water waves.

Total Internal Reflection takes place when light travels from a denser medium to a lighter medium. Conditions of total internal reflection are:

• The angle of incidence must be greater than the critical angle.
• The light ray moves from a more dense medium to a less dense medium.

Examples of total internal reflection are:

• Mirage is an example of total internal reflection.
• Diamonds shine due to this phenomenon.
• Optical fiber, which is the most essential component in communication, works on the principle of total internal reflection.
• Glass prisms can be designed to generate total internal reflection, and are incorporated in telescopes, binoculars, periscopes, and other optical instruments.

Formulas:

Total internal reflection is given by the formula:

Critical angle, Ө =

Important Total Internal Reflection Questions with Answers

1. Choose YES or NO: Is the shining crack in a glass vessel an example of total internal reflection?

1. YES
2. NO

Answer: YES

Explanation: Yes, the shining crack in a glass vessel is an example of total internal reflection.

2. Which of the following waves can undergo total internal reflection?

1. Water wave
2. Sound wave
3. Light wave
4. All the above options

Answer: d) All the above options

Explanation: Electromagnetic waves, light waves, microwaves, sound waves as well as water waves can undergo total internal reflection.

3. Fill in the blanks: The angle of incidence must be _____ than the critical angle.

1. Same
2. Lesser
3. Greater
4. Always zero

Answer: c) Greater

Explanation: For a wave to undergo total internal reflection, the angle of incidence must be greater than the critical angle.

4. Can a microwave undergo total internal reflection?

Yes, microwaves can undergo total internal reflection. When the microwaves travel from denser to lighter medium and have oblique incidence, it undergoes total internal reflection.

5. Which optical instruments undergo total internal reflection?

1. Telescopes and microscopes
2. Binoculars
3. Spectroscopes and periscopes
4. All the above options

Answer: d) All the above options

Explanation: All the above mentioned optical instruments can undergo total internal reflection.

6. Fill in the blanks: The brilliance of a diamond is due to _____

1. Diffraction
2. Reflection
3. Refraction
4. Total internal reflection

Answer: d) Total internal reflection

7. What is the index of refraction?

When the speed of light in a vacuum is divided by the speed of light in the medium, it is known as the index of refraction.

8. What is the formula to find the index of refraction?

1. n=c+v
2. n=c*v
3. n=c-v
4. n=c/v

Answer: d) n=c/v

9. Fill in the blanks: Electromagnetic radiation is created due to periodic change in _____

1. Electric field
2. Magnetic field
3. Both electric field and magnetic field
4. Space

Answer: c) Both electric field and magnetic field

10. What is the index of refraction of ice?

1. 0
2. 1
3. 1.31
4. 2.49

Answer: c) 1.31

Explanation: index of refraction of ice (n) is 1.31.

Practice Questions

1. Define total internal reflection.
2. What is an electromagnetic wave?
3. Define critical angle.
4. What is the formula to find the critical angle?
5. State true or false: The angle of incidence must be greater than the critical angle for a wave to undergo total internal reflection.

Watch the video below to learn about the total internal reflection experiment in water.