======Atomic Spectra With a Diffraction Grating======


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**Alternative titles:** Fingerprint of Atoms: Emission Lines, Emission Spectra
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====Summary====                   
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====Procedure====  
  - Set up the spectroscope with the collimator and telescope aligned.  
  - Place the gas discharge tube in front of the collimator and switch on the power supply.  
  - Look through the telescope to view the central bright line of the emitted light.  
  - Slowly rotate the telescope to one side to observe the first-order spectral lines.  
  - Rotate further to find repeated patterns representing higher-order diffraction lines.  
  - Record the colors and positions of the lines for comparison with known spectra.



====Links==== 
Seeing Atomic Spectra - SMUPhysics: 
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📄 How to See Atomic Spectra - Classroom Physics Demos: [[https://demos.smu.ca/demos/optics/67-spectral-lines]]\\

====Variations====
  * Try different gas tubes (hydrogen, helium, neon, mercury) to compare emission spectra.  
  * Use a handheld diffraction grating to view spectra without a full spectroscope setup.  
  * Measure the diffraction angles and calculate the wavelengths of the observed lines.



====Safety Precautions====
  * Handle gas discharge tubes carefully—they are fragile and can break if dropped.  
  * Do not touch the powered electrodes of the lamp.  
  * Ensure the lamp is turned off before changing tubes.




====Questions to Consider====
  * Why does each element produce a unique set of emission lines? (Because each atom has specific electron energy levels, and photons are emitted only when electrons drop between these levels.)  
  * Why are the emission lines discrete rather than continuous? (Electrons can only occupy certain quantized energy states.)  
  * How does a diffraction grating separate light into its components? (It diffracts and interferes with light waves so different wavelengths are directed at different angles.)  
  * How could emission spectra be used in astronomy? (By analyzing light from stars, scientists can identify which elements are present in distant celestial objects.)