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Blackbody Curves

Something I worked on last night. Wrote a program to generate relative radiance curves for ideal blackbodies at different temperatures from Planck’s Law, used Excel to graph them and then embellished in Photoshop. These emission curves explain why very hot objects become incandescent, and the integrals of these curves determine their colour (cooler objects glow dull red, hot objects glow yellow-orange, and very hot objects glow blue-white). The gradient is modified from David Eccles’ normalised linear spectrum, which was released to the public domain. My modifications mean that the spectrum is only qualitatively correct, placing more emphasis on yellow.

Blackbody emission curves for various temperatures

Blackbody emission curves via Planck's Law at 3000, 4000 and 5000 K - cc-by-sa 3.0

This adventure was inspired by an exercise in my ancient copy of Atkins Physical Chemistry, which asks readers to write a program that outputs blackbody spectra and optionally numerically integrates them. There’s also a question involving a glow worm being propelled through space via photon momentum, quite a charming imagination 😀