Suppose a ray of light traveling in a material with an index of refraction na reaches an interface with a material having an index of refraction nb. Which of the following statements must be true for total internal reflection to occur? a. The angle of incidence must be less than the critical angle.
b. The angle of incidence must be equal to the critical angle.
c. The angle of incidence must be greater than the critical angle.

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.6 m below the tank bottom which is a = 6.7 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute). report your answer in meters to two decimal places.