Refraction: Light Speed, Ray Bending, and Snell’s Law

All flashcards

What is refraction?

Refraction is the change in a light ray’s direction when it passes between materials with different refractive indices.

What does the index of refraction describe?

It describes how the speed of light in a material compares with its speed in a vacuum. The relationship is $n = c/v$.

What is the normal to a boundary?

The normal is an imaginary line perpendicular to the boundary at the point where the light ray crosses it. Refraction angles are measured from this line.

What happens when light enters a higher-index material?

Light slows down and its ray bends toward the normal.

What is Snell’s law?

For light passing between two media, Snell’s law is $n_1\sin\theta_1 = n_2\sin\theta_2$, with both angles measured from the normal.

Quiz questions

1. How is the speed of light in a material related to its refractive index?Answer: It is given by $v = c/n$.
2. Which equation expresses Snell’s law for light passing from medium 1 into medium 2?Answer: $n_1\sin\theta_1 = n_2\sin\theta_2$
3. Light travels from air ($n_1 = 1.00$) into a material at an incident angle of $30.0^\circ$. If its refracted angle is $22.0^\circ$, what is the material’s refractive index?Answer: Approximately 1.33
4. A light ray reflects from a boundary at an angle of incidence of $35^\circ$. What is its angle of reflection?Answer: $35^\circ$
5. What does the reversibility of a refracted ray’s path mean?Answer: Traveling back through the same boundary reverses the ray’s path.