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SpectraSound Extension Activities: Laser Scratching with a Comb

Combing LaserTo Do

Find a hair comb. Set up your SpectraSound system with your favorite dance music. Then run the comb through the SpectraSound laser.


You will hear that the signal is interrupted every time the comb fingers block the beam. You will hear a sound that is similar to a record scratching.

Every time the amount of light hitting the solar cell changes, it changes the electric current going to the speaker. A change in current is called an electrical signal. This signal causes the speaker to vibrate and emit sound. When you pass the comb through the laser, you create a series of electrical signals that sounds like a record scratching. After some practice, you will be able to laser scratch to your favorite tunes and sound just like DJ Qbert.

Finally, choose a laser dj name using your favorite laser terms. Here are a few examples: Ruby rod, population inversion, wavelength, diode, HeNe, 535mn, stimulated emission, continuous wave, photon, coherent.

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