Light of wavelength 589 nm passes through a pair of slits to form an interference pattern on a screen 400 cm away (vertical scale is intensity). The ruler is in cm (that is, from the "4" to the "5" is one centimeter). Find the separation between the slits in micrometers to within 15%.

Afisherman notices that his boat is moving up and down periodically without any horizontal motion, owing to waves on the surface of the water. it takes a time of 2.20 s for the boat to travel from its highest point to its lowest, a total distance of 0.670 m . the fisherman sees that the wave crests are spaced a horizontal distance of 5.80 m apart. (a) how much is the wavelength? (b) find the period of the wave. (c) how fast are the waves traveling? (d) what is the amplitude a of each wave?