posted by Anonymous .
A certain type of laser emits light that has a frequency of 4.7 1014 Hz. The light, however, occurs as a series of short pulses, each lasting for a time of 2.8 10-11 s. (a) How many wavelengths are there in one pulse? (b) The light enters a pool of water. The frequency of the light remains the same, but the speed of the light slows down to 2.3 108 m/s. How many wavelengths are there now in one pulse?