Why does a stick appear bent when it is partially submerged in water?
Answer: A tilted stick partially submerged in water appears curved when viewed from above. This is for the refraction of light. The light rays from the part of the stick above the water come directly to our eyes and we see that part of the stick in real space. As rays from each point of the submerged part of the stick are refracted from the denser medium to the thinner medium, the inverse of each point is formed slightly above the actual position of that point.
As a result, the reflection of the outer part of the stick and the submerged part of the water are not in the same straight line, making the stick appear curved.