Invisibility and Refractive Index – Rankers Physics

Refraction by Prism: Practice Problem & Solution

Assertion (A): A completely transparent material will be invisible in vacuum, when the refractive index is unity. Reason (R): The ratio of the refractive index of red light to blue light in vacuum is less than unity.  
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; if a material's refractive index matches the surrounding (vacuum, \(\mu=1\)), light passes through without deviation or reflection, making it invisible. Reason (R) is false; in vacuum, the refractive index is \(1\) for all colors, so their ratio is \(1\), not less than unity. Thus, A is true and R is false.

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