A fisherman looks at a fish in clear water and wants to hit it with a spear…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A fisherman looks at a fish in clear water and wants to hit it with a spear. Should he aim at the place where the fish seems to be, above it, or below it? Explain with refraction.
Need a reminder? The key ideaShow
A ray through a glass slab leaves parallel to the way it came (), shifted sideways by the lateral displacement . Looking straight down into water, : things look shallower.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. The light. Light from the fish leaves the water and bends away from the normal.
Step 2. The eye. The eye traces the bent ray straight back, so the fish seems higher than it is.
Step 3. The aim. The real fish is deeper.
Answer: he must aim below the place where the fish seems to be.
Check. It is the same effect that makes a pool look shallow.
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