消えるビーカー（屈折率マッチング）

屈折率が一致する液体に沈めることでガラス物体を見えなくする

Classroom Demonstrations Beginner (Middle School) 15 分 ~$8.00

目的

ガラス物体をその屈折率と一致する液体の中で見えなくさせ、屈折率の概念を実証する。

背景

We see transparent objects like glass because light bends (refracts) at the surface where the glass meets air. The degree of bending depends on the difference in refractive index between the two media. If a glass object is placed in a liquid with the same refractive index, light passes through without bending, and the object becomes effectively invisible. Pyrex glass (n ≈ 1.474) nearly matches vegetable oil (n ≈ 1.47), creating a stunning visual effect.

安全上の警告

  • Vegetable oil is slippery — clean up spills immediately to prevent falls
  • Glass objects can break — handle with care

必要なPPE

goggles

材料

  • Vegetable oil (or glycerol) (500 mL)
    Refractive index ≈ 1.47
  • Pyrex glass beaker or rod (1)
    To disappear
  • Regular glass rod (1)
    For comparison (different n)

器具

Large glass beaker (1 L) or clear container

手順

1

Fill the large beaker about 2/3 full with vegetable oil.

2 分
2

Show the Pyrex glass object to the audience. Note that it is clearly visible in air.

1 分
3

Slowly lower the Pyrex glass into the vegetable oil. As it submerges, it gradually becomes invisible.

3 分 Lower gently to avoid splashing
4

For comparison, lower the regular glass rod into the same oil. It remains visible because its refractive index does not match.

3 分
5

Discuss: light refracts at boundaries between materials with different refractive indices. When n values match, no refraction occurs and the object seems to disappear.

6 分

予想される結果

The Pyrex glass becomes nearly invisible when submerged in vegetable oil. Only slight distortions at the edges may be visible. The regular glass rod remains clearly visible in the same oil.

後片付け

Remove glass objects and wash with dish soap. Oil can be saved for reuse or disposed of in general waste. Wipe up any oil spills.

詳細

カテゴリ
Classroom Demonstrations
難易度
Beginner (Middle School)
所要時間
15 分
推定費用
$8.00
ステップ数
5
材料
3

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Frequently Asked Questions

What is the objective of 消えるビーカー（屈折率マッチング）?
ガラス物体をその屈折率と一致する液体の中で見えなくさせ、屈折率の概念を実証する。
How difficult is 消えるビーカー（屈折率マッチング）?
This experiment is rated as Beginner (Middle School). It takes approximately 15 minutes to complete.
What safety precautions are needed for 消えるビーカー（屈折率マッチング）?
Key safety precautions include: Vegetable oil is slippery — clean up spills immediately to prevent falls; Glass objects can break — handle with care.
What materials are needed for 消えるビーカー（屈折率マッチング）?
The main materials required are: Vegetable oil (or glycerol), Pyrex glass beaker or rod, Regular glass rod.
What results should I expect from 消えるビーカー（屈折率マッチング）?
The Pyrex glass becomes nearly invisible when submerged in vegetable oil. Only slight distortions at the edges may be visible. The regular glass rod remains clearly visible in the same oil.