1. A light beam is passed through 100 m of liquid with an index of refraction n = 1.7. How long does it take the light to traverse the 100 m with and without the liquid?
2. A flashlight beam has an exit power of 100 mW, an exit diameter of 4 cm, and a divergence of 1.2°. Calculate the intensity in at 60 m and the size of the beam at that distance.