A fish tank of length L contains a vertical partition with an embedded lens. An arrow is taped to the left wall of the tank. When only the left section of the tank is filled with water, a sharp image of the arrow appears on the right wall of the tank. The length of that image is . If instead only the right section of the tank is filled with water, another sharp image of the arrow appears on the right wall. Find (a) the distance between the lens and the left wall, (b) the length of the second image, and (c) the length of the arrow. The index of refraction of water is n.
Many readers from all over the world submitted their solutions to our February Challenge, A Double Triple —but not too many solutions were entirely correct. Looking back, the column editor...