Red light of wavelength 632 nm in free space is incident at an angle of $\t$theta = 39^\circ$ with respect to the normal on a glass slide of thickness d = 0.78 mm and index of refraction n = 1.52. The wavelength of light in glass will become

Correct Answer: (A) 316 nm

The wavelength of light in a medium is given by $\lambda$_m = $\lambda$_0 / n, where $\lambda$_0 is the wavelength in free space (632 nm) and n is the refractive index (1.52). Calculating this gives $\lambda$_m = 632 / 1.52 = 416 nm, wait, standard calculation gives 632 / 1.52 = 415.78 nm approx 416 nm. Let's check calculation: 632 / 1.52 = 415.78. Option says 416 nm.