13.2.3 | revision #19513 | Savchenko Solutions

Statement

13.2.3. A snail sits on the far wall of a rectangular aquarium of width $$l$$ . By what factor will the apparent angular size of the snail change if the water is drained from the aquarium? The observer is located at a distance $$L$$ from the aquarium.

Solution

In the previous problem we proved that the apparent width of the aquarium will be $$n$$ times smaller than the real one. The angular size at large distances is inversely proportional to the distance $\to$

$\alpha' = \alpha \frac{L+\frac{l}{n}}{L+l}$

Answer

$\alpha' = \alpha \frac{L+\frac{l}{n}}{L+l}$