Silly Saturday

Is it rather silly to blip a photograph of a humble saucepan? I think it probably is.

However, whilst heating a pan of milk to make my Editor a mug of milky coffee (yes, that's how she likes it...I prefer an Americano with a drop of cold milk) I was intrigued to notice this rainbow effect on the side of the pan.

It's probably also a little silly (or nerdy anyway) to start pondering the physics behind such a phenomenon. (Note: If you're not a nerd* like me you may wish to stop reading now!) I'm assuming that the milk had sloshed around a bit as I poured it into the pan, leaving a thin film which as it heated up became transparent. If this film was similar in thickness to the layer of oil one sometimes sees on top of a puddle of water on the road, one can imagine it producing a rainbow effect by the same principle. Light travelling through the film would be reflected from the saucepan wall back through the film and merge with light reflected directly from the film surface itself, but only at certain angles of incidence of the light (depending on the wavelength) will they be in phase with each other. As different colours of light have different wavelengths, they will experience constructive or destructive interference at different angles of incidence (the angle of incidence affects the path length through the thin film).

I think I may be very silly to start pondering these things in the kitchen whilst making coffee: my Editor certainly thinks so!

Thanks so much to admirer for hosting Silly Saturday, especially as she's not too well at the moment.

(* Note: I Googled the definition of "nerd" and found two possible ones. The first is "a foolish or contemptible person who lacks social skills or is boringly studious" and the second is "a single-minded expert in a particular technical field". Naturally I prefer the second but fear that the first may be more accurate...!)