25.3 The Law of Refraction

When light travels from air into water, which of the following statements is accurate?

1. The wavelength decreases, and the speed decreases.
2. The wavelength decreases, and the speed increases.
3. The wavelength increases, and the speed decreases.
4. The wavelength increases, and the speed increases.

Students in a lab group are given a plastic cube with a hollow cube-shaped space in the middle that fills about half the volume of the cube. The index of refraction of the plastic is known. The hollow space is filled with a gas, and the students are asked to collect the data needed to find the index of refraction of the gas. What information would you need to collect, and how would you use this in…

A laser is fired from a submarine beneath the surface of a lake (n = 1.33). The laser emerges from the lake into air with an angle of refraction of 67°. How fast is the light moving through the water? What is the angle of incidence of the laser light when it crosses the boundary between the lake and the air?

What is the speed of light in water? In glycerine?

Calculate the index of refraction for a medium in which the speed of light is $2 . \text{012} \times \text{10}^{8} \text{ m}/\text{s}$, and identify the most likely substance based on the table.

There was a major collision of an asteroid with the Moon in medieval times. It was described by monks at Canterbury Cathedral in England as a red glow on and around the Moon. How long after the asteroid hit the Moon, which is $3 . \text{84} \times \text{10}^{5} \text{ km}$ away, would the light first arrive on Earth?

Components of some computers communicate with each other through optical fibers having an index of refraction $n = 1 . \text{55}$. What time in nanoseconds is required for a signal to travel 0.200 m through such a fiber?

Suppose you have an unknown clear substance immersed in water, and you wish to identify it by finding its index of refraction. You arrange to have a beam of light enter it at an angle of $\text{45} . 0º$, and you observe the angle of refraction to be $\text{40} . 3º$. What is the index of refraction of the substance and its likely identity?

Suppose light travels from water to another substance, with an angle of incidence of $\text{10} . 0º$ and an angle of refraction of $\text{14} . 9º$. (a) What is the index of refraction of the other substance? (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?

Light traveling from water to a gemstone strikes the surface at an angle of $\text{80} . 0º$ and has an angle of refraction of $\text{15} . 2º$. (a) What is the speed of light in the gemstone? (b) What is unreasonable about this result? (c) Which assumptions are unreasonable or inconsistent?