A fish is at a depth d below the surface of a water tank. A cat observes the fish from air. Due to refraction at water-air interface, the apparent depth of the fish will be:

Solution

When light passes from a denser medium (water) to a rarer medium (air) , it bends away from the normal , making the object appear closer to the surface than it actually is. This is why a submerged object (like a fish) appears at a shallower depth to an observer in air. This phenomenon leads to the concept of apparent depth , given by: Where: • d = real depth • μ = refractive index of water relative to air (>1) Since μ > 1, it follows that: Apparent depth < d  Therefore, correct answer is option (c).