Just dug out some ancient ticker tape machines to use as an alternative way to measure g by free fall. I'm having problems getting reliable marks on the tape, sometimes the strike bounces and leaves two marks, sometimes marks don't get left at all, especially at low speed at the start of the...
OK, so nobody can give me a clear answer. Here's a hypothesis: it's caused by reflections. What I see myself is a number of duplicate images of the edge of my finger. Could each part of the skin, in between the cracks of the fingerprints, be flat enough to cause an individual reflection? The...
My physics master at school (1970s) said that if you hold your hand in front of your eye whilst looking at a bright light, you can see lines appear in the tiny gaps between the fingers. He said that though some people thought this was slit diffraction, they were mistaken, the effect actually...