Lesson: Emission and Absorption Spectra Physics • 9th Grade

In this lesson, we will learn how to determine the composition of a material from the features that appear in the spectrum of light coming from it.

Lesson Plan

Students will be able to

identify types of spectra by looking at diagrams of them: continuous spectrum, emission spectrum, and absorption spectrum,
identify whether an emission or absorption line is present in two different spectra,
identify elements in a mixture based on the spectrum of the mixture and the spectrum of the individual elements,
see that lines in a spectrum have widths,
determine the width of a spectral line by looking at a diagram of a spectrum.

Lesson Video

Lesson Explainer

Sample Question Videos

02:39

Lesson Worksheet

Q1:

A scientist has a sample of an unknown gas. In order to identify it, she shines a continuous spectrum of white light through the gas and observes which wavelengths of light are absorbed by it. This is shown in the figure, as well as the absorption spectra of five pure, gaseous elements. Which of the five elements is the unknown gas?

Q2:

A scientist has a sample of an unknown gas. In order to identify the gas, he looks at the spectrum of visible light emitted from it when it is heated. This is shown in the figure. Also shown in the figure are the emission spectra of five pure, gaseous elements. Which of the five elements is the unknown gas?

Q3:

A scientist has a sample of an unknown gas. In order to identify the gas, she looks at the spectrum of visible light emitted from it when it is heated. This is shown in the figure. Also shown in the figure are the emission spectra of three pure, gaseous elements. Which of the three elements is the unknown gas?