Béquer Desaparecendo (Correspondência de Índice de Refração)

Tornando um objeto de vidro invisível ao imergir em um líquido de índice de refração correspondente

Classroom Demonstrations Beginner (Middle School) 15 min ~$8,00

Objetivo

Demonstrar o conceito de índice de refração tornando um objeto de vidro invisível em um líquido que corresponde ao seu índice de refração.

Contexto

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.

Avisos de segurança

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

EPI necessário

goggles

Materiais

  • 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)

Equipamentos

Large glass beaker (1 L) or clear container

Procedimento

1

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

2 min
2

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

1 min
3

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

3 min 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 min
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 min

Resultados esperados

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.

Limpeza

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.

Detalhes

Categoria
Classroom Demonstrations
Dificuldade
Beginner (Middle School)
Duração
15 min
Custo estimado
$8,00
Passos
5
Materiais
3

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Frequently Asked Questions

What is the objective of Béquer Desaparecendo (Correspondência de Índice de Refração)?
Demonstrar o conceito de índice de refração tornando um objeto de vidro invisível em um líquido que corresponde ao seu índice de refração.
How difficult is Béquer Desaparecendo (Correspondência de Índice de Refração)?
This experiment is rated as Beginner (Middle School). It takes approximately 15 minutes to complete.
What safety precautions are needed for Béquer Desaparecendo (Correspondência de Índice de Refração)?
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 Béquer Desaparecendo (Correspondência de Índice de Refração)?
The main materials required are: Vegetable oil (or glycerol), Pyrex glass beaker or rod, Regular glass rod.
What results should I expect from Béquer Desaparecendo (Correspondência de Índice de Refração)?
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.