A spectroscope is a simple device that allows students to see the spectrum of light by splitting white light into different colors. This is a great project to introduce concepts of light, wavelengths, and color dispersion.
๐ง Materials Required
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CD/DVD (old, scratched ones work fine!) โ Acts as a diffraction grating
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Cardboard Box (small shoe box or cereal box) โ Acts as the spectroscope body
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Razor Blade or Craft Knife โ To make precise cuts
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Black Paper or Paint โ To reduce unwanted reflections
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Tape & Glue โ To secure parts
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Slit Cutout (Aluminum Foil or Cardboard with a Slit) โ Creates a narrow beam of light
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Flashlight or Sunlight โ Light source
๐ ๏ธ How to Build the Spectroscope
Step 1: Prepare the Box
- Cut a small rectangular hole on one side of the box (~1 cm wide).
- This is where light will enter the spectroscope.
Step 2: Create the Light Slit
- Cut a thin vertical slit (~1mm wide) on aluminum foil or cardboard.
- Tape it over the hole you made in Step 1.
- The slit should be very narrow and straight to create a sharp spectrum.
Step 3: Install the Diffraction Grating
- Take an old CD or DVD and carefully cut a small triangular section (~5 cm wide).
- Place it inside the box at an angle (about 45ยฐ) so light passing through the slit hits the CD surface.
- Secure it with tape or glue.
Step 4: Viewing Window
- Cut a small viewing hole on the opposite side of the CD.
- This is where you’ll look through to see the spectrum.
Step 5: Finishing Touches
- Paint the inside black or line it with black paper to prevent stray reflections.
- Ensure all gaps are sealed with tape to block out extra light.
๐ How to Use the Spectroscope
1๏ธโฃ Point the light slit toward a bright light source (like sunlight or a flashlight).
2๏ธโฃ Look through the viewing hole and observe the beautiful rainbow spectrum!
3๏ธโฃ Try using different light sources (LED, CFL, Sunlight) and compare the spectra.
๐ Science Behind It
- The CD/DVD surface acts like a diffraction grating, breaking light into its different wavelengths.
- Different light sources have unique spectral lines (e.g., fluorescent vs. LED vs. sunlight).
- This is how real spectrometers analyze stars, gases, and chemicals! ๐โจ
๐ ๏ธ Spectroscope Diagram

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