Coal burns with a red glow.

What is the ignition temperature of coal?

If it is T, and I take another substance which has melting point quite above T, and heat it to T, Will it also emit red light?

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    $\begingroup$ Yes. Blackbody radiation is blackbody radiation regardless of what is emitting it (with some caveats that are material specific thrown in). After enough time around furnaces, you have a pretty good feel for what temperature emits what colors from just below 500C to 600C and slightly above. $\endgroup$ – Jon Custer May 10 '16 at 14:05

Don't confuse the ignition temperature with the temperature of a burning coal. One is the temperature required to start the reaction, the other is the equilibrium temperature achieved when the substance is burning.

As for the colour of things at a given temperature, the colour will be broadly the same at the same temperature: this is black body radiation. For an interesting take on this in the context of movies, see this amusing video about why movies get it wrong on casting iron swords. A key point is that the glowing colour shown in most movies is far too cool (too orange red) for molten iron (which should be much whiter). Movies cheat and use aluminium which melts at less than 700 °C and glows orange. Iron needs ~1,600 °C and glows far whiter.

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