Question

A laser beam with vacuum wavelength 632.8 nm is incident from air onto a block of Lucite as shown in the figure below. The line of sight of the photograph is perpendicular to the plane in which the light moves. (Assume that the incidence angle is 63

Answer 1

According to laws of reflection.

Snells Law

in 01 Tm1

we will get

1) here lets take the refractive index of air to be 1 and the Lucite crystal to be 1.5.

If the index of refraction in lucite is 1.5, then, from Snell's Law, the speed of light in lucite is 3 * 10^8 m per second / 1.5 = 2 * 10^8 m per second.

2) While the speed of light changes in a different medium, its frequency does not, so the frequency will still be "c" /632.8 nm = 4.7*10¹⁴ Hz

3)The wavelength will contract proportional to the change in the speed of light, so it will be (632.8 / 1.5) nm =421.8 nm.