PADI Divemaster Certification Practice Exam

When light refracts while entering water, what is the ratio that makes objects appear closer?

1. 3:2

2. 4:3

3. 5:4

4. 1:1

The correct answer is: 4:3

When light transitions from air to water, it slows down due to the denser medium. This change in speed causes light to bend, a phenomenon known as refraction. The ratio that is commonly cited to explain how much closer objects appear under water compared to their actual position is 4:3. This means that for every 4 units of visual distance through water, the object appears to be only at 3 units from the observer's perspective. This effect is a valuable consideration for divers, as it influences how they perceive distances underwater. Understanding this ratio helps divers effectively gauge their surroundings and adjust their movements accordingly, ensuring safety and enhancing the overall diving experience.