| Wavelengths In Spectrum Of A Gas |
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Aim : |
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The aim of this experiment is to
measure the wavelengths in the spectrum of a gas.
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Materials : |
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- A gas discharge lamp and
transformer
- A spectrometer
- A dark room
- A diffraction grating
- Magnifying lens
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Procedure :
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- Level the spectrometer
table.
- Set up the spectrometer with the collimator adjusted to produce parallel light and the
telescope to receive it.
- Put the grating on the spectrometer table at right
angles to the axis and facing towards the
telescope.
- Measure the angle between a given line in the first order on either side of the central
maximum. Half of this angle will give the angle of diffraction (A).
- Repeat this for as many lines as can be seen.
- Record the number of line per metre (N) on the diffraction grating and hence find the grating
spacing (e = 1/N)
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Conclusion : |
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You can calculate the wavelengths
(λ) from n λ = esinA.
where, n is the order of the spectrum
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