Law of refraction

Definition

The Law of Refraction, or Snell's Law, describes how light bends when it passes from one medium into another. It is mathematically expressed as $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$, where $n$ is the refractive index and $\theta$ is the angle of incidence or refraction.

5 Must Know Facts For Your Next Test

1. Snell's Law formula is $n_1 \sin(\theta_1) = n_2 \sin(\theta_2)$.
2. The refractive index ($n$) is a measure of how much light slows down in a medium.
3. Angles in Snell's Law are measured from the normal (a line perpendicular to the surface).
4. When light enters a denser medium (higher refractive index), it bends towards the normal.
5. Total internal reflection occurs when light tries to move from a denser to a less dense medium at an angle greater than the critical angle.

Review Questions

• What is the mathematical expression for Snell's Law?
• How does light behave when it travels from a less dense to a more dense medium?
• What happens during total internal reflection?

Related terms

Refractive Index:

A dimensionless number that describes how fast light travels through a material.

Critical Angle:

The minimum angle of incidence at which total internal reflection occurs.

Normal Line:

An imaginary line perpendicular to the surface at the point of incidence or refraction.