Question

A ray of light passes from vacuum into a medium of refractive index µ, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is ______.

Options

• `2cos^-1(mu/2)`

• sin^-1(μ)

• `sin^-1(mu/2)`

• `cos^-1(mu/2)`

Answer 1

A ray of light passes from vacuum into a medium of refractive index µ, the angle of incidence is found to be twice the angle of refraction. Then the angle of incidence is `underlinebb(2cos^-1(mu/2))`.

Explanation:

µ = `sin"i"/sin"r"` ∵ i = 2r

⇒ µ = `(sin2"r")/sin"r"=(2sin"r".cos"r")/sin"r"` 

r = `cos^-1(mu/2)`,

∴ i = `2cos^-1(mu/2)`