Home Physics Ray Optics Total Internal Reflection The critical angles for total internal refle…
Physics Ray Optics Total Internal Reflection Subjective Type
Published on: September 12, 2026

The critical angles for total internal reflection is ......... when a ray of light travels from glass to water than when it travels from glass to air.

Share this question

For Instagram sharing, use “Apps” on mobile or copy the link.

Text Solution

Verified by Experts
The correct answer is:
B
Step 1: Understand the concept of critical angle. The critical angle is defined as the angle of incidence above which total internal reflection occurs. It depends on the index of refraction of the two media involved.
Step 2: The formula for critical angle ($C$) is given by Snell's Law as follows:
$$C = ext{sin}^{-1} \left( \frac{n_2}{n_1} \right)$$ where
- $n_1$ is the refractive index of the medium from which the light is coming (glass in this case)
- $n_2$ is the refractive index of the second medium (water or air).
Step 3: For glass to air, typically, the refractive index of glass is around 1.5 and air is approximately 1. Thus, the critical angle when light moves from glass to air is:
$$C_{glass-air} = \text{sin}^{-1} \left( \frac{1}{1.5} \right)$$
Step 4: For glass to water, the refractive index of water is about 1.33. Thus, the critical angle when light moves from glass to water is:
$$C_{glass-water} = \text{sin}^{-1} \left( \frac{1.33}{1.5} \right)$$
Step 5: Comparing the two critical angles calculated, we find that the critical angle for glass to air is greater than that for glass to water:
Thus, the statement in the question indicates that the critical angle for total internal reflection is less when a ray of light travels from glass to water than from glass to air.
Therefore, the correct answer is Option B.

Prepare Smarter with CGP Edu

Get practice questions, solutions, and test series in one place.

Write a Review

Share your experience with this question and solution.

Commentary

Send your comment, doubt, correction, or feedback to admin.

Student Reviews

What students say about this solution

No reviews yet. Be the first to write a review.

Similar Questions

Explore conceptually related problems

CG
CGP Question Assistant Question Bank + AI Help
Hi! Type your question or upload one screenshot. First I will search related questions from CGP Edu Question Bank. If none match, type YES and I will solve it with AI.
Upload only one screenshot at a time. Flow: Question Bank first → If not matched, type YES for AI solution.