Recognising Line Spectra
A spectrum is produced by separating radiation according to wavelength. First learn what the three common spectra look like.
Recognise continuous, emission and absorption spectra
A continuous spectrum contains an unbroken band of wavelengths. A line spectrum contains separate bright or dark lines.
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| Spectrum | How it is produced | Appearance |
|---|---|---|
| Continuous | A hot dense source emits a continuous range of wavelengths. | Every wavelength in the range is present. |
| Emission line | Excited atoms in a low-density gas emit photons. | Bright lines on a dark background. |
| Absorption line | Continuous radiation passes through a cooler gas. | Dark lines across a continuous spectrum. |
Your turnrecognition check
Continuous radiation passes through a cooler low-density gas. What spectrum is observed after the radiation is separated by wavelength?
Show worked answer
An absorption line spectrum: dark lines appear across the continuous spectrum at the absorbed wavelengths.