{"id":63699,"date":"2026-05-23T04:38:28","date_gmt":"2026-05-22T19:38:28","guid":{"rendered":"https:\/\/phys-edu.net\/wp\/?p=63699"},"modified":"2026-05-23T04:38:28","modified_gmt":"2026-05-22T19:38:28","slug":"can-two-glass-plates-and-tape-create-a-rainbow-we-built-a-diy-device-to-see-light-interference-in-action","status":"publish","type":"post","link":"https:\/\/phys-edu.net\/wp\/?p=63699&lang=en","title":{"rendered":"Can Two Glass Plates and Tape Create a Rainbow? We Built a DIY Device to See Light Interference in Action"},"content":{"rendered":"

I\u2019m Kuwako Ken, your science trainer. Every day is an experiment.<\/strong><\/span><\/p>\n

Just by stacking two pieces of glass together, shimmering rainbow stripes suddenly appear. It feels almost like magic\u2014but this beautiful phenomenon can actually be recreated with everyday materials. All you need are two microscope slide glasses and a strip of transparent tape. In this experiment, we explored the mysterious behavior of light known as \u201cwedge-shaped interference.\u201d<\/p>\n

What Is Wedge Interference? A Phenomenon Caused by Light Acting Like a Wave<\/h3>\n

First, let\u2019s look at why these colorful stripes appear.<\/p>\n

Light behaves not only like particles, but also like waves. When a tiny layer of air exists between two glass plates, light reflects off both the top and bottom surfaces of that air gap. These two reflected waves overlap with each other. When wave peaks line up, the light becomes brighter. When peaks and valleys overlap, they cancel each other out and become darker. This is called interference<\/b>.<\/p>\n

The air layer between the two glasses isn\u2019t perfectly uniform\u2014it gradually changes thickness like a wedge. Because the thickness changes from place to place, different colors strengthen or weaken at different points, producing those beautiful rainbow stripes.<\/p>\n

In fact, this is exactly the same principle<\/b> behind the rainbow colors on soap bubbles or the oily patterns floating on puddles after rain. The same hidden physics is already all around us in daily life.<\/p>\n

How to Build the Device \u2014 You Only Need Four Simple Materials<\/h3>\n

For this experiment, we used two large microscope slide glasses. The setup is incredibly simple. Place a strip of transparent tape on one edge of one glass plate to create a tiny gap, then place the second glass plate on top. Finally, press the glasses together firmly using clips or your fingers.<\/p>\n

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A single layer of tape is about 0.05 millimeters thick\u2014around 50 micrometers. That\u2019s roughly half the thickness of a human hair<\/b>. This incredibly tiny gap becomes the stage where light waves interfere with each other.<\/p>\n

For comparison, the wavelength of visible light is more than a thousand times smaller still. Inside this microscopic air layer, light is performing an astonishingly delicate dance.<\/p>\n

What You\u2019ll See \u2014 Rainbow Stripes Appear Near Your Finger<\/h3>\n

When you press the glass more tightly with your finger and shine sunlight or another bright light onto it, faint vertical stripes begin to appear. Take a look at the video below.<\/p>\n