Science project

Portable Photon Kit

  1. To understand double-slit interference.     
  2. To make the demonstration of this effect more accessible.     

Research Questions:     

  • What is the double slit experiment?     
  • What causes the interference?     
  • How can this phenom be more easily demonstrated?    

The double slit interference experiment is one of the strangest puzzles in the known universe. The phenomenon is more than just hard to explain. A demonstration of the effect is logistically annoying. We don't all live near physics labs, where physicists handle equipment so sensitive that a mere glance from a human eye disturbs the subatomic particles they study. In this project you build a portable photon kit by which you can demonstrate double slit interference anywhere, any time.


  • Computer with Internet access     
  • Color printer     
  • Digital camera     
  • Typical office/hobby/hardware/craft supplies (paper, poster board, glue, etc.).     
  • Black cardboard     
  • Exacto knife     
  • Black electrical tape     
  • One Key ring light     
  • One piece of black fabric about 12”x12”.     

All necessary materials can be found in or around your home, at local stores, or on ebay.

Experimental Procedure:     

  1. Read overview of relevant topics (see bibliography below and terms listed above)     
  2. Address all of the above terms and research questions.     
  3. Search and print out interesting images relevant to your topic.     
  4. Take photographs throughout the course of the experiment.     
  5. Using thick black cardboard, create a cubic box that opens on one side with a flap.     
  6. Use an exacto knife to remove the side of the box opposite the flap.     
  7. Cut two thin, vertical, parallel slits, about an inch long and placed fairly close together in the cardboard piece that you removed.     
  8. Reattach the piece to the box securely, making sure it's still it removable.     
  9. In a darkened room, try to create an interference pattern on the wall by holding the key-ring light inside the box so it shines through the slits, while covering the box and your hand with the black fabric.     
  10. If you fail to produce an interference pattern at first, try moving the light source around. Or remove the cut piece from the box and make a new one, changing the distance between the two slits. Keep tweaking the apparatus until you get it right.     
  11. When finished, place the light and the fabric inside the box and show everyone your portable photon kit.     
  12. Analyze your data.     
  13. Interpret your findings in a detailed report.     
  14. Include photos, diagrams, models and demonstrations in your science fair display.  

Terms/Concepts: Interference Pattern; Quantum Mechanics; Wave-Particle Theory


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Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state's handbook of Science Safety.

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