A horizontal cylindrical tank 2.20 m in diameter is half full of water. The space above the water is filled with a pressurized gas of unknown refractive index. A small laser can move along the curved bottom of the water and aims a light beam toward the center of the water surface. You observe that when the laser has moved a distance S= 1.12 or more (measured along the curved surface) from the lowest point in the water, no light enters the gas. a. What is the index of refraction of the gas?
b. How long does it take the light beam to travel from the laser to the rim of the tank when S >1.12 m?
c. How long does it take the light beam to travel from the laser to the rim of the tank when S<1.12 m?