Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)

Membuat benda kaca tak terlihat dengan merendamnya dalam cairan dengan indeks bias yang cocok

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

Tujuan

Demonstrasikan konsep indeks bias dengan membuat benda kaca menghilang dalam cairan yang cocok dengan indeks biasnya.

Latar Belakang

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.

Peringatan Keselamatan

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

APD yang Diperlukan

goggles

Bahan

  • 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)

Peralatan

Large glass beaker (1 L) or clear container

Prosedur

1

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

2 menit
2

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

1 menit
3

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

3 menit 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 menit
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 menit

Hasil yang Diharapkan

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.

Pembersihan

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.

Detail

Kategori
Classroom Demonstrations
Tingkat Kesulitan
Beginner (Middle School)
Durasi
15 menit
Perkiraan Biaya
$8,00
Langkah
5
Bahan
3

Eksperimen Lainnya

Cairan Non-Newton: Ooblek 20 min Kemiluminensensi dengan Luminol 30 min Kolom Kerapatan Pelangi 30 min Pasta Gigi Gajah 20 min Pembakaran Magnesium dalam Es Kering 25 min Pembekuan Seketika: Air Superdingin 120 min Reaksi Jam Iodin 45 min Reaksi Natrium dan Air 25 min Reaksi Osilasi Briggs-Rauscher 40 min Reaksi Termit 30 min

Frequently Asked Questions

What is the objective of Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)?
Demonstrasikan konsep indeks bias dengan membuat benda kaca menghilang dalam cairan yang cocok dengan indeks biasnya.
How difficult is Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)?
This experiment is rated as Beginner (Middle School). It takes approximately 15 minutes to complete.
What safety precautions are needed for Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)?
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 Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)?
The main materials required are: Vegetable oil (or glycerol), Pyrex glass beaker or rod, Regular glass rod.
What results should I expect from Gelas Kimia yang Menghilang (Pencocokan Indeks Bias)?
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.