Problem Solving: A coin at the bottom of a cylinder appears to be 12.6 cm deep when the cylinder is filled with water. What is the real depth pf the coin in water? Oil, with an index of refraction of 1.25, is added to the cylinder. The coin now appears to be 17.6 cm deep. (b) What is the real depth of the coin in oil and water? ( n = real depth/ apparent depth)