Question

Each part of Fig. 33-34 shows light that refracts through an interface between two materials. The incident ray (shown gray in the figure) consists of red and blue light. The approximate index of refraction for visible light is indicated for each material. Which of the three parts show physically possible refraction? (Hint: First consider the refraction in general, regardless of the color, and then consider how red and blue light refract differently?

Short answer

None of the parts shows physically possible refraction.

Step-by-step solution

The given data

Figure 33-34 consists of three cases that show refraction through an interface between two materials.

Understanding the concept of bending due to refraction

Analyzing the given figure and using the concept of refraction, we can predict the part that shows physically possible refraction. For a material with a higher refractive index, the light bends towards the normal line, while for a material with a low refractive index, it speeds up and bends away from the normal line.

Calculation to get the possible case of refraction

Let’s draw the normal to the surfaces.

When light travels from a rarer to a denser medium, it refracts towards the normal, and when it travels from a denser to a rarer medium, it refracts away from the normal.

In part (a), light travels from a rarer to a denser medium, and red light is refracted away from the normal.

So, this part is not physically possible.

In part (b), incident and refracted lines are on the same side of the normal.

So, this part is not physically possible.

In part (c), light travels from a denser to a rarer medium. Blue light must bend more than red as the refractive index of blue light is more than that of red light.

So, this part is not physically possible.

Hence, none of the above-given cases is physically possible.