Dispersion in Glass Slab – Rankers Physics

Refraction by Prism: Practice Problem & Solution

Assertion (A): A ray of white light shows no dispersion on emerging from a glass slab although there occurs dispersion inside the glass slab. Reason (R): The velocity of light inside the glass slab is same for all different colours.  
Both (A) & (R) are true and the (R) is the correct explanation of the (A)
Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(A) is true but (R) is false
Both (A) and (R) are false

Solution Explained:

To solve this problem, we apply the core principles of Refraction by Prism. Understanding the underlying formula is key to arriving at the correct answer below:

Assertion (A) is true; due to the parallel surfaces of the glass slab, the dispersed colors recombine upon emerging, showing no net dispersion. Reason (R) is false; dispersion occurs precisely because the velocity of light (and thus refractive index) varies for different colors within the medium. Thus, A is true and R is false.

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Similar Practice Questions

Explore conceptually related problems to test your knowledge.

1. Assertion (A): A solid glass sphere is placed in air. A light ray enters into the sphere from outside. The ray cannot undergo total internal reflection inside the sphere. Reason (R): The angle of incidence at \(\text{1}^ \ext{st}\) surface cannot be greater than the critical angle for air-glass system.  
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