Mysterious Bowl

Let's take a look!

What type of experiment is this?

Experimental procedure and explanation:

• Let’s try an experiment with a mysterious bowl.
• When water is poured into the bowl, a hidden medal suddenly appears. Why does this happen?
• This is due to light refraction—the same principle demonstrated in the experiment “Principle of Optical Fiber.”
• When light travels between materials with different densities (such as water and air), it bends or refracts. Pouring water into the bowl changes how the light bends, allowing the hidden medal to become visible.
• When light passes between two different materials, the relationship shown in the diagram applies:
  \[ \frac{\rm{sin}θ_1}{\rm{sin}θ_2}=\frac{n_2}{n_1} \] where θ₁ is the angle of incidence, θ₂ is the angle of refraction, n₁ is the refractive index of the incident medium (e.g., 1.33 for water), and n₂ is the refractive index of the refracted medium (e.g., 1.00 for air).

• When light passes from water into air, the angle of refraction becomes larger than the angle of incidence. This bending of light makes the medal visible.
• This video was produced with the support of the JSPS Grant-in-Aid for Scientific Research (18K03956).

[Keywords]	Refraction of light
[Related items]	Principles of Optical Fiber

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