Mystery #2Tier 2barcodes and light
How does the little red beam at a shop till read those black-and-white stripes?
At the shop till a little red beam flickers over your shopping and, beep, the price pops up on the screen. All it seems to look at is a band of black and white stripes. Yet somehow that flash of light knows exactly what you are buying. How does the little red beam at a shop till read those black-and-white stripes?
Your guess
What do you think happens to the beam as it crosses the black stripes and the white gaps?
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