Or maybe it should be on refraction. Possibly it’s a new feature but most probably it´s just one I never noticed, but you can shine white light through a prism in Algodoo and you get a spectrum. I used to do it by placing red green and blue lasers on top of each other but this is simpler. The spectrum isn´t continuous by the way, which is interesting. So thanks go to Adrian who made the discovery. Last year Philip, Hamza, Balder, Carsten and especially Herman were always feeding me with ideas for my blog so I need some replacements.

I thought I´d try to make a rainbow by shining light on a load of water drops but I soon realized I´d need 3 dimensions to get the bow shape, maybe a GeoGebra project? I could construct rays coming off the water droplets at different angles and define their colour depending on which ray meets the observer, Hmm. The animation shows why the high drops appear red and the lower one blue.

A different sort of reflection: Today I forgot to take my laptop to class and noticed how easier it seemed to be for students to ask me questions. Maybe when I sit at my computer the students think I´m busy and don’t want to disturb me?