1. The problem statement, all variables and given/known data Do magnets attract all metals, and is the speed of light in a water constant? 2. Relevant equations None that I know of 3. The attempt at a solution I would assume that magnets attract almost all metals because they have an electron sea in them and they would be attracted to the magnet. But what about the speed of light in water? My physics teacher said that the speed of light in water depends on the medium it comes from. But I read that its always a constant value (3 *10^8m/s / 1.33) Is it true that the speed of light in water would be different if the light came from a vacuum, compared to if the light came from say a diamond?