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Energy, Heat & MotionThermal Radiation

The Color of Heat

Hot things reveal their temperature through the color they glow

Blacksmiths could tell how hot their steel was just by looking at it. What were they reading in that glow?

You'll find out

  • Why every hot thing glows red first
  • How fast the glow brightens with heat
  • Why old bulbs were mostly heaters

Why it matters

Glowing heat tells the temperature of forges, stars and light bulbs. It's also why LEDs save power.

About 3 min6 interactive slides · 5 questionsLesson 219 · Zone 25

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