Q1. A thin layer of magnesium fluoride (n = 1.38) is used to coat a flint-glass lens (n = 1.61). What minimum thickness must the magnesium fluoride film have if the reflection of 667 nm light is to be suppressed? Presume that the light is incident at right angles to film. In nm
Q2. A uniform plank of length 5.9 m and weight 212 N rests horizontally on two supports, with 1.1 m of the plank hanging over the right support .To what distance x can a person who weighs 443 N walk on overhanging part of the plank before it just begins to tip?