Spectrum Table

Quick Answer: The Spectrum Table is a spectrum chart for the physics or chemistry wall that sets out the spectrum of light, typically the continuous visible spectrum alongside emission and absorption line spectra of elements. It is used in lessons on light, spectroscopy and atomic structure.

Continuous, Emission and Absorption Spectra

White light spread by a prism or diffraction grating gives a continuous band of colour from violet, at wavelengths of roughly 400 nm, to red, at about 700 nm. A spectrum chart typically starts with that band and a wavelength scale, then shows what happens with other light sources: a hot, low-pressure gas gives bright coloured lines at particular wavelengths, its emission spectrum, while a cooler gas in front of a white source removes the same wavelengths as dark lines, its absorption spectrum.

The value of the chart is comparison. Hydrogen, helium, sodium, mercury and neon each have a distinctive pattern of lines, a fingerprint set by the energy levels of their electrons. Sodium’s bright yellow pair explains the colour of sodium street lamps; the dark Fraunhofer lines in sunlight revealed which elements are present in the sun, and helium was found there before it was discovered on earth. Some spectrum charts also place visible light within the wider electromagnetic spectrum, from radio waves to gamma rays.

Specifications

Applications

• Comparing spectra seen through a hand spectroscope or diffraction grating with the chart
• Flame tests: relating the colours of sodium, lithium and copper flames to their line spectra
• Explaining electron energy levels and photon emission in atomic structure lessons
• Introducing how astronomers identify the composition of stars from their light

Care & Handling

• Hang the chart under ordinary white light; coloured lighting changes how the printed spectrum looks.
• Keep it out of direct sun so the printed colours stay true enough for comparison work.
• Place it near the blackout blinds or dark corner where spectroscope work is done.

Why Choose LabEquip

Physics teachers use this chart alongside the prisms, gratings and spectroscopes in the Light & Optics range, so students can compare what they observe with a reference, and chemistry teachers pair it with the Illustrated periodic table when linking line spectra to electron shells. The chart is part of Educational Charts; orders go through the LabEquip contact page.

Frequently Asked Questions

What is the difference between an emission and an absorption spectrum?

An emission spectrum is a set of bright coloured lines given out by a hot gas. An absorption spectrum is a continuous spectrum crossed by dark lines where a cooler gas has absorbed the same wavelengths it would emit.

Why does each element have its own line spectrum?

Electrons in an atom can occupy only certain energy levels. When an electron drops between levels it emits a photon of an exact energy, and so an exact wavelength, and each element has its own set of levels.

How can students see spectra in a school laboratory?

Look at a gas discharge tube, a sodium lamp or a fluorescent light through a hand spectroscope or a diffraction grating. A white filament lamp gives a continuous spectrum for comparison.

What are Fraunhofer lines?

They are the dark absorption lines in the spectrum of sunlight, caused by elements in the cooler outer layers of the sun absorbing specific wavelengths. They were mapped in the early nineteenth century and later used to identify the sun’s elements.

How is the chart linked to flame tests?

The colour of a flame test comes from the emission lines of the metal. Sodium gives a strong yellow, lithium red and copper blue-green, and a spectroscope splits these colours into the separate lines a spectrum chart shows.

What range of wavelengths does visible light cover?

Roughly 400 nm for violet to 700 nm for red. Shorter wavelengths lie in the ultraviolet and longer ones in the infrared, both invisible to the eye but part of the same electromagnetic spectrum.

Last Updated: September 2026