Question: Keeping the observer and the cup in the same positions, only replace the transparent liquid to be poured into the cup from pure water to glycerol (all other conditions the same). To make a previously invisible small target at the bottom of the cup appear in view for the first time, how will the minimum required liquid level change compared with using water?
A. A higher liquid level is needed
B. Roughly unchanged
C. A lower liquid level is needed
D. Determined only by the target’s size and unrelated to the liquid being poured
Clues:
1. A sequence of four images shows a white mug against a black background.
2. In the first two images, a coin is shown falling into the mug.
3. In the third image, the mug is empty, and the bottom of the mug is not visible from the camera's angle.
4. In the fourth image, the mug contains a transparent liquid, and the coin is now visible at the bottom.
5. The visibility of the coin at the bottom of the mug is dependent on the presence of a liquid inside it.
Answer: C
Category: Physics