Assertion and Reason for Snell’s Law and Light in Medium – Rankers Physics

Refraction by Plane Surfaces: Practice Problem & Solution

Assertion (A): The Snell's law \(\mu sin \theta = \text{constant}\) is valid at different boundaries irrespective of the shape of the boundaries. Reason (R): When light enters from vacuum into a medium of refractive index \(\mu\), its speed and wavelength increases by \(\mu\).  
(1) Both (A) & (R) are true and the (R) is the correct explanation of the (A)
(2) Both (A) & (R) are true but the (R) is not the correct explanation of the (A)
(3) (A) is true but (R) is false
(4) Both (A) and (R) are false

Solution Explained:

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

Snell's law is valid universally for light refraction. However, when light enters a medium of refractive index \(mu\) from vacuum, its speed and wavelength *decrease* by a factor of \(mu\), not increase. Thus, A is true, but R is false.

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