WAEC Physics 2014 Paper

Concept:For normal viewing from above, the real depth of an object in water is the product of refractive index and apparent depth.Explanation:The apparent depth of the fish is $1.5\,m$.The refractive index of water is $n = 1.3$.Using the relation:$$\text{Real depth} = n \times \text{apparent depth}$$$$\text{Real depth} = 1.3 \times 1.5 = 1.95\,m$$The apparent displacement is the difference between the real depth and the apparent depth:$$\text{Apparent displacement} = 1.95 - 1.5 = 0.45\,m$$Answer:The apparent displacement of the fish is $0.45\,m$.Correct option: D. $0.45\,m$