Primary and Secondary Bow of a Rainbow

• E+60+95

A cylinder containing water (or glycerine) is set up with a collumated beam of light slightly wider than the cylinder itself incident on it (the halogen bulb works well, doesn’t require an additional lens since light beam emerges somewhat collumated). The light enters the cylinder and, in a fashion similar to the inside of a raindrop, has a primary and secondary rainbow emerge. The first bow exhibits the colors ROYGBIV and the second bow is slightly spread out and displays VIBGYOR (it is also about 10% as bright). This demo can be difficult to see because of loss within the system. There is considerable scattering of white light backwards however both bows can be observed if carefully set up and projected on a screen.