Aplastic cube is immersed in water having an index of refraction of 1.33. a laser beam in the plastic strikes the interface at an angle of 14.5° with the normal in the plastic. in the water, this beam makes an angle of 21.8° with the normal. what is the speed of light in the plastic cube? (c = 3.0 × 108 m/s)

157077501.7 m/s

Explanation:

Refractive index of water = n₂ = 1.33

θ₁ = 14.5°

θ₂ = 21.8°

According to Snell's law

Refractive index of plastic is 1.973

∴ Speed of light in the plastic cube is 157077501.7 m/s

one "light year" is the distance that light travels, through vacuum, in one julian year.   that's 365.25 days, of 24 hours each.