Konstanta fisika

Konstanta fisika atau tetapan fisika adalah besaran fisika yang umumnya dipercaya secara universal di alam dan konstan terhadap waktu. Berkebalikan dengan konstanta matematika yang nilai numeriknya tetap namun tidak berhubungan dengan pengukuran fisika manapun.

Berbagai konstanta fisika dasar

Banyak konstanta fisika dalam ilmu sains, salah satu yang paling umum misalnya kecepatan cahaya dalam ruang vakum c, konstanta gravitasi G, konstanta Planck h, konstanta listrik ε₀, dan muatan elementer e. Konstanta fisika dapat menjelaskan berbagai bentuk analisis dimensional: kecepatan cahaya meningkatkan drastis batas kecepatan maksimum alam semesta dan dinyatakan secara dimensional sebagai panjang dibagi waktu; sedangkan konstanta struktur-halus α yang mengkarakterisasikan kekuatan interaksi elektromagnetik, adalah satuan tak berdimensi.

Tabel konstanta universal

Quantity l b s	Simbol	Nilai[1][2]	Ketidakpastian standar relatif
kecepatan cahaya dalam vakum	${\displaystyle c\,}$	299 792 458 m·s−1	terdefinisi
konstanta gravitasi Newton	${\displaystyle G\,}$	6,67408(31)×10−11 m3·kg−1·s−2	4.7 × 10−5
konstanta Planck	${\displaystyle h\,}$	6.626 070 040(81) × 10−34 J·s	1.2 × 10−8
konstanta Planck tereduksi	${\displaystyle \hbar =h/(2\pi )}$	1.054 571 800(13) × 10−34 J·s	1.2 × 10−8

Tabel konstanta elektromagnetik

Quantity l b s	Simbol	Nilai[1][3] (satuan SI)	Ketidakpastian standar relatif
konstanta magnetik (permeabilitas vakum)	${\displaystyle \mu _{0}\,}$	4π × 10−7 N·A−2 = 1.256 637 061... × 10−6 N·A−2	terdefinisi
konstanta listrik (permitivitas vakum)	${\displaystyle \varepsilon _{0}=1/\mu _{0}c^{2}\,}$	8.854 187 817... × 10−12 F·m−1	terdefinisi
impedansi ruang hampa	${\displaystyle Z_{0}=\mu _{0}c\,}$	376.730 313 461... Ω	terdefinisi
konstanta Coulomb	${\displaystyle k_{\mathrm {e} }=1/4\pi \varepsilon _{0}\,}$	8.987 551 787... × 109 N·m2·C−2	terdefinisi
muatan elementer	${\displaystyle e\,}$	1.602 176 565(35) × 10−19 C	2.2 × 10−8
magneton Bohr	${\displaystyle \mu _{\mathrm {B} }=e\hbar /2m_{\mathrm {e} }}$	9.274 009 68(20) × 10−24 J·T−1	2.2 × 10−8
kuantum konduktansi	${\displaystyle G_{0}=2e^{2}/h\,}$	7.748 091 7346(25) × 10−5 S	3.2 × 10−10
invers kuantum konduktansi	${\displaystyle G_{0}^{-1}=h/2e^{2}\,}$	12 906.403 7217(42) Ω	3.2 × 10−10
konstanta Josephson	${\displaystyle K_{\mathrm {J} }=2e/h\,}$	4.835 978 70(11) × 1014 Hz·V−1	2.2 × 10−8
kuantum fluks magnetik	${\displaystyle \phi _{0}=h/2e\,}$	2.067 833 758(46) × 10−15 Wb	2.2 × 10−8
magneton nuklir	${\displaystyle \mu _{\mathrm {N} }=e\hbar /2m_{\mathrm {p} }}$	5.050 783 53(11) × 10−27 J·T−1	2.2 × 10−8
konstanta von Klitzing	${\displaystyle R_{\mathrm {K} }=h/e^{2}\,}$	25 812.807 4434(84) Ω	3.2 × 10−10

Tabel konstanta atom dan nuklir

Quantity l b s		Simbol	Nilai[1][3] (satuan SI)	Ketidakpastian standar relatif
radius Bohr		${\displaystyle a_{0}=\alpha /4\pi R_{\infty }\,}$	5.291 772 1092(17) × 10−11 m	3.2 × 10−9
radius elektron klasik		${\displaystyle r_{\mathrm {e} }=e^{2}/4\pi \varepsilon _{0}m_{\mathrm {e} }c^{2}\,}$	2.817 940 3267(27) × 10−15 m	9.7 × 10−10
massa elektron		${\displaystyle m_{\mathrm {e} }\,}$	9.109 382 91(40) × 10−31 kg	4.4 × 10−8
konstanta berpasangan Fermi		${\displaystyle G_{\mathrm {F} }/(\hbar c)^{3}}$	1.166 364(5) × 10−5 GeV−2	4.3 × 10−6
konstanta struktur-halus		${\displaystyle \alpha =\mu _{0}e^{2}c/2h=e^{2}/4\pi \varepsilon _{0}\hbar c\,}$	7.297 352 5698(24) × 10−3	3.2 × 10−10
Energi Hartree		${\displaystyle E_{\mathrm {h} }=2R_{\infty }hc\,}$	4.359 744 34(19) × 10−18 J	4.4 × 10−8
massa proton		${\displaystyle m_{\mathrm {p} }\,}$	1.672 621 777(74) × 10−27 kg	4.4 × 10−8
kuantum sirkulasi		${\displaystyle h/2m_{\mathrm {e} }\,}$	3.636 947 5520(24) × 10−4 m2 s−1	6.5 × 10−10
konstanta Rydberg		${\displaystyle R_{\infty }=\alpha ^{2}m_{\mathrm {e} }c/2h\,}$	10 973 731.568 539(55) m−1	5.0 × 10−12
Thomson cross section		${\displaystyle (8\pi /3)r_{\mathrm {e} }^{2}}$	6.652 458 734(13) × 10−29 m2	1.9 × 10−9
sudut campur lemah		${\displaystyle \sin ^{2}\theta _{\mathrm {W} }=1-(m_{\mathrm {W} }/m_{\mathrm {Z} })^{2}\,}$	0.2223(21)	9.5 × 10−3
faktor Efimov		${\displaystyle }$	22.7

Tabel konstanta fisika-kimia

Quantity l b s		Simbol	Nilai[1][3] (satuan SI)	Ketidakpastian standar relatif
konstanta massa atom		${\displaystyle m_{\mathrm {u} }=1\,\mathrm {u} \,}$	1.660 538 921(73) × 10−27 kg	4.4 × 10−8
bilangan Avogadro		${\displaystyle N_{\mathrm {A} },L\,}$	6.022 141 29(27) × 1023 mol−1	4.4 × 10−8
konstanta Boltzmann		${\displaystyle k=k_{\mathrm {B} }=R/N_{\mathrm {A} }\,}$	1.380 6488(13) × 10−23 J·K−1	9.1 × 10−7
konstanta Faraday		${\displaystyle F=N_{\mathrm {A} }e\,}$	96 485.3365(21)C·mol−1	2.2 × 10−8
konstanta radiasi pertama		${\displaystyle c_{1}=2\pi hc^{2}\,}$	3.741 771 53(17) × 10−16 W·m2	4.4 × 10−8
	untuk radiansi spektral	${\displaystyle c_{\mathrm {1L} }=c_{1}/\pi \,}$	1.191 042 869(53) × 10−16 W·m2·sr−1	4.4 × 10−8
konstanta Loschmidt	at ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=101.325 kPa	${\displaystyle n_{0}=N_{\mathrm {A} }/V_{\mathrm {m} }\,}$	2.686 7805(24) × 1025 m−3	9.1 × 10−7
konstanta gas		${\displaystyle R\,}$	8.314 4621(75) J·K−1·mol−1	9.1 × 10−7
konstanta molar Planck		${\displaystyle N_{\mathrm {A} }h\,}$	3.990 312 7176(28) × 10−10 J·s·mol−1	7.0 × 10−10
volume molar gas ideal	pada ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=100 kPa	${\displaystyle V_{\mathrm {m} }=RT/p\,}$	2.271 0953(21) × 10−2 m3·mol−1	9.1 × 10−7
	pada ${\displaystyle T}$=273.15 K and ${\displaystyle p}$=101.325 kPa		2.241 3968(20) × 10−2 m3·mol−1	9.1 × 10−7
konstanta Sackur-Tetrode	pada ${\displaystyle T}$=1 K and ${\displaystyle p}$=100 kPa	${\displaystyle S_{0}/R={\frac {5}{2}}}$ ${\displaystyle +\ln \left[(2\pi m_{\mathrm {u} }kT/h^{2})^{3/2}kT/p\right]}$	−1.151 7078(23)	2.0 × 10−6
	pada ${\displaystyle T}$=1 K and ${\displaystyle p}$=101.325 kPa		−1.164 8708(23)	1.9 × 10−6
konstanta radiasi kedua		${\displaystyle c_{2}=hc/k\,}$	1.438 7770(13) × 10−2 m·K	9.1 × 10−7
konstanta Stefan–Boltzmann		${\displaystyle \sigma =\pi ^{2}k^{4}/60\hbar ^{3}c^{2}}$	5.670 373(21) × 10−8 W·m−2·K−4	3.6 × 10−6
konstanta hukum perpindahan Wien		${\displaystyle b=hck^{-1}/\,}$ 4.965 114 231...	2.897 7721(26) × 10−3 m·K	9.1 × 10−7

Tabel nilai yang diadopsi

Besaran		Simbol	Nilai (satuan SI)	Ketidakpastian standar relatif
nilai konvensional konstanta Josephson[4]		${\displaystyle K_{\mathrm {J-90} }\,}$	4.835 979 × 1014 Hz·V−1	terdefinisi
nilai konvensional konstanta von Klitzing[5]		${\displaystyle R_{\mathrm {K-90} }\,}$	25 812.807 Ω	terdefinisi
massa molar	konstanta	${\displaystyle M_{\mathrm {u} }=M({}^{12}\mathrm {C} )/12\,}$	1 × 10−3 kg·mol−1	terdefinisi
	karbon-12	${\displaystyle M({}^{12}\mathrm {C} )=N_{\mathrm {A} }m({}^{12}\mathrm {C} )\,}$	1.2 × 10−2 kg·mol−1	terdefinisi
percepatan gravitasi standar (jatuh bebas di bumi)		${\displaystyle g_{\mathrm {n} }\,\!}$	9.806 65 m·s−2	terdefinisi
atmosfer standar		${\displaystyle \mathrm {atm} \,}$	101 325 Pa	terdefinisi

Satuan natural

Artikel utama: Satuan natural

Dengan menggunakan analisis dimensional, dimungkinkan untuk menggabungkan konstanta fisika universal untuk mendefinisikan sistem satuan pengukuran yang tidak memiliki acuan ke konstruksi manusia manapun. Bergantung dari pemilihan dan penataan konstanta yang digunakan, satuan natural yang dihasilkan mungkin dapat memiliki makna fisika yang berarti. Contohnya, satuan Planck, dibawah ini, menggunakan c, G, ħ, ε₀ dan k_B untuk menyatukan berbagai teori seperti gravitasi kuantum.

Base Planck units l b s
Nama	Dimensi	Dinyatakan	Nilai[6] (SI units)
panjang Planck	Panjang (L)	${\displaystyle l_{\text{P}}={\sqrt {\frac {\hbar G}{c^{3}}}}}$	1.616 199(97) × 10−35 m[7]
massa Planck	Massa (M)	${\displaystyle m_{\text{P}}={\sqrt {\frac {\hbar c}{G}}}}$	2.176 51(13) × 10−8 kg[8]
waktu Planck	Waktu (T)	${\displaystyle t_{\text{P}}={\frac {l_{\text{P}}}{c}}={\frac {\hbar }{m_{\text{P}}c^{2}}}={\sqrt {\frac {\hbar G}{c^{5}}}}}$	5.391 06(32) × 10−44 s[9]
muatan Planck	muatan listrik (Q)	${\displaystyle q_{\text{P}}={\sqrt {4\pi \varepsilon _{0}\hbar c}}}$	1.875 545 956(41) × 10−18 C[10][11][12]
temperatur Planck	Temperatur (Θ)	${\displaystyle T_{\text{P}}={\frac {m_{\text{P}}c^{2}}{k_{\text{B}}}}={\sqrt {\frac {\hbar c^{5}}{Gk_{\text{B}}^{2}}}}}$	1.416 833(85) × 1032 K[13]

Referensi

1. The values are given in the so-called concise form; the number in parentheses after the mantissa is the ketidakpastian standar, which is the value multiplied by the ketidakpastian standar relatif, and indicates the amount by which the least significant digits of the value are uncertain. For example, 75 is the standard uncertainty in "8.314 4621(75)", and means that the value is between 8.314 4546 and 8.314 4696.
2. Mohr, Peter J.; Newell, David B.; Taylor, Barry N.. "CODATA Recommended Values of the Fundamental Physical Constants: 2014". arΧiv:1507.07956v1 [physics.atom-ph].
3. P.J. Mohr, B.N. Taylor, and D.B. Newell (2011), "The 2010 CODATA Recommended Values of the Fundamental Physical Constants" (Web Version 6.0). This database was developed by J. Baker, M. Douma, and S. Kotochigova. Available: http://physics.nist.gov/constants [Thursday, 02-Jun-2011 21:00:12 EDT]. National Institute of Standards and Technology, Gaithersburg, MD 20899.
4. This is the value adopted internationally for realizing representations of the volt using the Josephson effect.
   
5. This is the value adopted internationally for realizing representations of the ohm using the efek kuantum Hall.
6. Fundamental Physical Constants from NIST
7. CODATA — Planck length
8. CODATA — Planck mass
9. CODATA — Planck time
10. CODATA — electric constant
11. CODATA — Planck constant over 2 pi
12. CODATA — speed of light in vacuum
13. CODATA — Planck temperature

• Mohr, Peter J.; Taylor, Barry N.; Newell, David B. (2008). "CODATA Recommended Values of the Fundamental Physical Constants: 2006". Rev. Mod. Phys. 80 (2): 633–730. arXiv:0801.0028 . Bibcode:2008RvMP...80..633M. doi:10.1103/RevModPhys.80.633.
• Barrow, John D. (2002), The Constants of Nature; From Alpha to Omega - The Numbers that Encode the Deepest Secrets of the Universe, Pantheon Books, ISBN 0-375-42221-8.

Pranala luar

• Sixty Symbols, University of Nottingham
• IUPAC - Gold Book