Refractive Index of Plano-Convex Lens – Rankers Physics
Topic: Ray Optics
Subtopic: Lens Makers Formula/ Len's Formula

Refractive Index of Plano-Convex Lens

The refractive index of material of a plano-convex lens, if the radius of curvature of convex surface is \(10\text{ cm}\) and focal length of lens is \(30\text{ cm}\) is
\(\mu = \frac{2}{3}\)
\(\mu = \frac{1}{3}\)
\(\mu = \frac{4}{3}\)
\(\mu = \frac{1}{2}\)

Solution:

Using lens maker's formula for a plano-convex lens, \(f = \frac{R}{\mu - 1}\). Substituting \(R = 10\text{ cm}\) and \(f = 30\text{ cm}\), we get \(30 = \frac{10}{\mu - 1}\) which gives \(\mu - 1 = \frac{1}{3}\). Therefore, \(\mu = \frac{4}{3}\).

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