Verschwindender Becher (Brechungsindexanpassung)

Ein Glasobjekt unsichtbar machen, indem es in eine Flüssigkeit mit gleichem Brechungsindex getaucht wird

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

Ziel

Das Konzept des Brechungsindex demonstrieren, indem ein Glasobjekt in einer Flüssigkeit mit gleichem Brechungsindex unsichtbar gemacht wird.

Hintergrund

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.

Sicherheitswarnungen

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

Erforderliche PSA

goggles

Materialien

  • 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)

Ausrüstung

Large glass beaker (1 L) or clear container

Durchführung

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.

Erwartete Ergebnisse

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.

Aufräumen

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.

Details

Kategorie
Classroom Demonstrations
Schwierigkeit
Beginner (Middle School)
Dauer
15 Min.
Geschätzte Kosten
$8,00
Schritte
5
Materialien
3

Weitere Experimente

Chemilumineszenz mit Luminol 30 min Dichtesäulen-Regenbogen 30 min Elefantenzahnpasta 20 min Iod-Uhr-Reaktion 45 min Nicht-newtonsche Flüssigkeit: Oobleck 20 min Oszillierende Briggs-Rauscher-Reaktion 40 min Reaktion von Natrium und Wasser 25 min Sofortgefrieren: unterkühltes Wasser 120 min Thermit-Reaktion 30 min Verbrennung von Magnesium in Trockeneis 25 min

Frequently Asked Questions

What is the objective of Verschwindender Becher (Brechungsindexanpassung)?
Das Konzept des Brechungsindex demonstrieren, indem ein Glasobjekt in einer Flüssigkeit mit gleichem Brechungsindex unsichtbar gemacht wird.
How difficult is Verschwindender Becher (Brechungsindexanpassung)?
This experiment is rated as Beginner (Middle School). It takes approximately 15 minutes to complete.
What safety precautions are needed for Verschwindender Becher (Brechungsindexanpassung)?
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 Verschwindender Becher (Brechungsindexanpassung)?
The main materials required are: Vegetable oil (or glycerol), Pyrex glass beaker or rod, Regular glass rod.
What results should I expect from Verschwindender Becher (Brechungsindexanpassung)?
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.