Lesson: Refraction of Light Physics • 9th Grade

In this lesson, we will learn how to describe refraction as the speed and direction change of light when passing between media of different densities.

Lesson Plan

Students will be able to

recognize that light travels at different speeds in different media,
recognize that the wavelength of light is different in different media but that frequency is constant,
recognize that the greater the refractive index of a substance, the slower light travels in the substance,
recognize that light incident nonnormally on a media boundary changes propagation direction,
define angle of refraction,
use Snell’s law to determine incident and refracted angles and values of refractive index.

Lesson Presentation

Lesson Video

Lesson Explainer

Sample Question Videos

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Lesson Worksheet

Q1:

A light ray traveling in water of refractive index 1.3 is incident on the flat surface of a plastic block with a refractive index of 1.6, traveling through the block at an angle of 45 degrees from the line normal to the surface. At what angle from the line normal to the surface does the incident ray strike the block? Answer to the nearest degree.

Q2:

A light ray traveling in water of refractive index 1.3 is incident on the flat surface of a plastic block with a refractive index of 1.7, hitting the surface at an angle of 45 degrees from the line normal to the surface. At what angle from the line normal to the surface does the refracted ray in the block travel? Answer to the nearest degree.

Q3:

A light ray traveling in water with a refractive index of 1.3 is incident on a flat boundary with air, hitting the boundary at an angle of 45 degrees from the line normal to the boundary. At what angle from the line normal to the boundary does the refracted ray in the air travel? Answer to the nearest degree.