Spectrum observed on heated vessel

Cromptu

Today i was heating a bowl of soup..the intensity of the flame of the gas stove was quite high..
i observed that the bowl got burnt and when it cooled down a bit, i observed a band of colours..blue was the most prominent..i noticed the presence of violet, yellow and orange too..
I wish to know the reason behind this..and the scientific view of what happened..
Thankyou :)

P.S - I don't know anything about the material of the bowl..And i have attached a picture of it too..

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Khashishi

This is a thin film effect, called iridescence. The material is some thin layer of corrosion, maybe chromium oxide. It doesn't really matter what the material is, as long as the material is thin and refractive. Light which penetrates the material and reflects off the metal will interfere with light which reflects off the material, either constructively or destructively, depending on the thickness of the film and the color of the light.

Cromptu

thankyou :)
also, why didn't this happen when i heated a similar bowl on a low intensity flame?
is it related to the oxidation?

Khashishi

Yeah. The reaction rate increases approximately exponentially with increasing temperature.