Raise your hand and hold it flat. Think of the space between your index finger and your middle finger as one slit, and think of the space between middle finger and ring finger as a second slit.
(a) Consider the interference resulting from sending coherent visible light perpendicularly through this pair of openings. Compute an order-of magnitude estimate for the angle between adjacent zones of constructive interference.
(b) To make the angles in the interference pattern easy to measure with a plastic protractor, you should use an electromagnetic wave with frequency of what order of magnitude? How is this wave classified on the electromagnetic spectrum?