All Exams Test series for 1 year @ ₹349 only
Question

Three parallel glass slabs of refractive indices 1.5, \(\sqrt{3}\) and 1.5 respectively have widths 2 mm, 1 mm and 4 mm. The combination is in air. Light is incident at the first slab at an angle of incidence \(\frac{\pi}{3}\). What is the angle with respect to the normal at which the light will emerge from the final surface?

This question was previously asked in
NDA 2 2026 GAT Question Paper (13-Sep-2026)
The correct answer is

\(\frac{\pi}{3}\)

For a set of parallel-faced slabs placed between the same medium (air) on both sides, Snell's law gives \(n_{0}\sin\theta_{0} = n_{1}\sin\theta_{1} = n_{2}\sin\theta_{2} = n_{3}\sin\theta_{3} = n_{0}\sin\theta_{f}\), since the initial and final medium is air (\(n_{0}=1\)), irrespective of the individual slab indices and thicknesses. Hence \(\sin\theta_{f} = \sin\theta_{0}\), so the emergent ray makes the same angle with the normal as the incident ray, i.e. \(\theta_{f} = \frac{\pi}{3}\). The correct option is (c).

Was this answer helpful?

Similar Questions

  1. A rainbow is produced due to which one of the following phenomenon?

  2. Consider the following statements about a microscope and a telescope:

    1. Both the eyepiece and the objective of a microscope are convex lenses.

    2. The focal length of the objective of a telescope is larger than the focal length of its eyepiece.

    3. The magnification of a telescope increases with the increase in focal length of its objective.

    4. The magnification of a microscope increases with the increase in focal length of its objective.

    Which of the statements given above are correct?
  3. Tyndall effect is a phenomenon of

  4. Power of a lens of focal length 25 cm is

  5. Which one of the following figures correctly shows the path of a ray of light through a glass prism:?

  6. When a light beam falls on a triangular glass prism, a band of colours is obtained. Which one of the following statements is correct in this regard ?

  7. If the focal length of a convex lens is 50 cm, which one of the following is its power?

  8. The refractive indices of two media are denoted by n 1and n 2, and the velocities of light in these two media are respectively v 1and v 2. If n 2/n 1is 1.5, which one of the following statements is correct?

  9. Which one of the following statements is correct for a plane mirror?

  10. An object is placed in front of a convex mirror. Which one of the following statements is correct?


Important Questions from Refraction and Reflection

  1. A convex lens of focal length f will form a magnified real image of an object, if the object is placed.

  2. A ray of light travelling in the direction \(\frac{1}{2} (\hat i + \sqrt 3 \hat j)\) is incident on a plane mirror. After reflection it travels along the direction  \(\frac{1}{2} (\hat i - \sqrt 3 \hat j)\)  The angle of incidence is:

  3. Twinkling of stars is due to atmospheric

  4. An optical fibre has a core material of refractive index of 1.55 and cladding material of refractive index of 1.50. The numerical aperture of the fibre is

  5. The refracting angle of a prism is $A$. The refractive index of the material of the prism is $\frac{1+\cos A}{\sin A}$. The angle of minimum deviation is:
Need Expert Advice?
Test Series
NDA img
Defence
NDA 2026 Mock Test Series (Latest Pattern)
503 Tests 1 Tests Free
1123 Attempts
4.6(139)
English, Hindi

Start Your Preparation with Prepp Mobile App

Download the app from Google Play & App Store
Download the app from Google Play & App Store
Prepp Mobile App