A submarine is observed to rise from a real depth off 80 m to 60 m in water. calculate the change in apparent depth.
[Refraction index of water (4)/3]
- 45 m
- 80 m
-
15 m
- 60 m
The correct answer is: C
Explanation
Refraction index (n)= (Real depth)/App. depthFor 80 m Real depth: (4)/3 = (80)/App. depth
App. dept = (80 x 3)/4 = 60 m
For 60 m real depth; (4)/3 = (60)/ App. depth
App. depth = (60 x 3)/4 = 45 m
∴change in App. depth = 60 -45 = 15 m