2. Calculate the gravitational acceleration due to gravity at an altitude of 400km above the earth's surface? (Mass of earth - 6x1024 kg and radius of Earth - 6400km)

Which statement is true if the refractive index of medium a is greater than that of medium b? a. total internal reflection is possible when light travels from air to medium b to medium a. b. total internal reflection is possible when light travels from medium a to medium b. c. total internal reflection is possible when light travels from medium b to medium a. d. total internal reflection is possible when light travels from air to medium a. e. total internal reflection is possible when light travels from air to medium b.