Indeks bias
Indeks bias pada medium didefinisikan sebagai perbandingan antara kecepatan cahaya di udara dengan cepat rambat cahaya di medium tersebut.
| Material | λ[1](nm) | n | Ref. |
|---|---|---|---|
| Vacuum | 1 (exactly) | ||
| Air @ STP | 1.0002926 | ||
| Gases @ 0 °C and 1 atm | |||
| Air | 589.29 | 1.000293 | [2] |
| Helium | 589.29 | 1.000036 | [2] |
| Hydrogen | 589.29 | 1.000132 | [2] |
| Carbon dioxide | 589.29 | 1.00045 | [3] |
| Liquids @ 20 °C | |||
| Benzene | 589.29 | 1.501 | [2] |
| Water | 589.29 | 1.3330 | [2] |
| Ethyl alcohol (ethanol) | 589.29 | 1.361 | [2] |
| Carbon tetrachloride | 589.29 | 1.461 | [2] |
| Carbon disulfide | 589.29 | 1.628 | [2] |
| Solids @ room temperature | |||
| Diamond | 589.29 | 2.419 | [2] |
| Strontium titanate | 589.29 | 2.41 | |
| Amber | 589.29 | 1.55 | [2] |
| Fused silica | 589.29 | 1.458 | [2] |
| Sodium chloride | 589.29 | 1.50 | [2] |
| Other materials | |||
| Pyrex (a borosilicate glass) | 1.470 | [6] | |
| Sapphire | 1.762–1.778 | ||
| Water ice | 1.31 | ||
| Cryolite | 1.338 | ||
| Acetone | 1.36 | ||
| Ethanol | 1.36 | ||
| Teflon | 1.35 - 1.38 | ||
| Glycerol | 1.4729 | ||
| Acrylic glass | 1.490 - 1.492 | ||
| Rock salt | 1.516 | ||
| Crown glass (pure) | 1.50 - 1.54 | ||
| Salt (NaCl) | 1.544 | ||
| Polycarbonate | 1.584 - 1.586 | ||
| PMMA | 1.4893 - 1.4899 | ||
| PETg | 1.57 | ||
| PET | 1.5750 | ||
| Flint glass (pure) | 1.60 - 1.62 | ||
| Crown glass (impure) | 1.485 - 1.755 | ||
| Fused Quartz | 1.46 | ||
| Bromine | 1.661 | ||
| Flint glass (impure) | 1.523 - 1.925 | ||
| Cubic zirconia | 2.15 - 2.18 | ||
| Moissanite | 2.65 - 2.69 | ||
| Cinnabar (Mercury sulfide) | 3.02 | ||
| Gallium(III) phosphide | 3.5 | ||
| Gallium(III) arsenide | 3.927 | ||
| Silicon | 4.01 | [7] | |
Secara matematis, indeks bias dapat ditulis:
dimana:
- n = indeks bias
- c = kecepatan cahaya dalam ruang hampa (299,792,458 meter/detik)
- = cepat rambat cahaya pada suatu medium
Indeks bias tidak pernah lebih kecil dari 1 atau (n ≥ 1).
Pembiasan
Jika seberkas cahaya datang dan membentuk sudut terhadap permukaan, maka berkas cahaya tersebut ada yang dibelokkan sewaktu memasuki medium baru tersebut, dimana pembelokan itu disebut dengan pembiasan.
Referensi
- ^ untuk panjang gelombang (λ) ditentukan dengan menggunakan panjang gelombang kuning = 589.29 nm
- ^ a b c d e f g h i j k l Optics, Fourth Edition. Pearson Higher Education. 18 March 2003. ISBN 9780321188786.
- ^ Introduction to Geometrical and Physical Optics. McGraw-Hill Book Company, INC. 1953.
- ^ Handbook of Chemistry and Physics. Chemical Rubber Publishing Co. 1957.
- ^ Introduction to Optics, Third Edition. Pearson Prentice Hall. 2007. hlm. 221. ISBN 0-13-149933-5.
- ^ University of Liverpool. "Absolute Refractive Index". Diakses tanggal 2007-10-18.
- ^ "Optical Properties of Silicon". Diakses tanggal 2009-05-31.
Bacaan selanjutnya
- Tipler, Paul A. and Ralph A. Llewellyn, (2003), Modern Physics. 4th ed. New York; W. H. Freeman and Company. ISBN 0-7167-4345-0. 222-3 pp.
- Léon Brillouin, (1960), "Wave Propagation And Group Velocity" Academic Press Inc., New York and London ISBN 0-12-134968-3.
- Main, Iain G., (1988), Vibrations and Waves in Physics. 2nd ed. New York; Cambridge University Press. ISBN 0-521-27846-5. 214-6 pp.