ভৌত ধ্রুবক

পদার্থবিজ্ঞানে, একটি ভৌত ধ্রুবক হল একটি ভৌত রাশির মান যা সার্বজনীন হিসেবে গৃহীত হয় এবং বিশ্বাস করা হয় যে এর মান সময়ের সাথে পরিবর্তিত হয় নাা।

 সার্বজনীন ধ্রুবক 
QuantitySymbolValueRelative Standard Uncertaintycharacteristic impedance of vacuum376.730 313 461... Ωdefinedelectric constant (permittivity of free space)8.854 187 817... × 10−12F·m−1definedmagnetic constant (permeability of free space)4π × 10−7 N·A−2 = 1.2566 370 614... × 10−6 N·A−2definedNewtonian constant of gravitation6.6742(10) × 10−11m3·kg−1·s−21.5 × 10−4Planck's constant6.626 0693(11) × 10−34 J·s1.7 × 10−7Dirac's constant1.054 571 68(18) × 10−34 J·s1.7 × 10−7speed of light in vacuum299 792 458 m·s−1defined

 তাড়িতচুম্বক ধ্রুবক 
QuantitySymbolValue1 (SI units)Relative Standard UncertaintyBohr magneton927.400 949(80) × 10−26 J·T−18.6 × 10-8conductance quantum7.748 091 733(26) × 10−5 S3.3 × 10−9Coulomb's constant8.987 742 438 × 109 N·m2C−2definedJosephson constant483 597.879(41) × 109 Hz· V−18.5 × 10−8magnetic flux quantum2.067 833 72(18) × 10−15 Wb8.5 × 10−8nuclear magneton5.050 783 43(43) × 10−27 J·T−18.6 × 10−8resistance quantum12 906.403 725(43) Ω3.3 × 10−9von Klitzing constant25 812.807 449(86) Ω3.3 × 10−9

 আণবিক ও পারমাণবিক ধ্রুবক 
{| border="1" align="center" 
|- style="background:#A0E0A0;" align="center"
| colspan=2| Quantity||Symbol||Value1 (SI units)||Relative Standard Uncertainty
|- 
| colspan=2 |Bohr radius||||5.291 772 108 (18) × 10−11 m||3.3 × 10−9
|-
|colspan=2| Fermi coupling constant||||1.166 39(1) × 10−5 GeV−2||8.6 × 10−6
|-
|colspan=2 |fine-structure constant||||7.297 352 568(24) × 10−3||3.3 × 10−9
|-
|colspan=2 |Hartree energy||||4.359 744 17(75) × 10−18 J||1.7 × 10−7
|-
|colspan=2 |quantum of circulation||||3.636 947 550(24) × 10−4 m2 s−1||6.7 × 10−9
|-
|colspan=2 |Rydberg constant||||10 973 731.568 525(73) m−1||6.6 × 10−12
|-
|colspan=2 |Thomson cross section||||0.665 245 873(13) × 10−28 m2||2.0 × 10−8
|-
|colspan=2 |weak mixing angle||||0.222 15(76)</td>
3.4 × 10−3
|-
|}

 গাঠনিক রসায়নের ধ্রুবক 
QuantitySymbolValue1 (SI units)Relative Standard Uncertaintyatomic mass constant (unified atomic mass unit)1.660 538 86(28) × 10−27 kg1.7 × 10−7Avogadro's number6.022 1415(10) × 10231.7 × 10−7Boltzmann constant1.380 6505(24) × 10−23 J·K−11.8 × 10−6Faraday constant96 485.3383(83)C·mol−18.6 × 10−8first radiation constant 3.741 771 38(64) × 10−16 W·m21.7 × 10−7for spectral radiance1.191 042 82(20) × 10−16 W · m2 sr−11.7 × 10−7Loschmidt constantat =273.15 K and =101.325 kPa2.686 7773(47) × 1025 m−31.8 × 10−6gas constant8.314 472(15) J·K−1·mol−11.7 × 10−6molar Planck constant3.990 312 716(27) × 10−10 J · s · mol−16.7 × 10−9molar volume of an ideal gasat =273.15 K and =100 kPa22.710 981(40) × 10−3 m3 ·mol−11.7 × 10−6at =273.15 K and =101.325 kPa22.413 996(39) × 10−3 m3 ·mol−11.7 × 10−6Sackur-Tetrode constantat =1 K and =100 kPa -1.151 7047(44)3.8 × 10−6at =1 K and =101.325 kPa-1.164 8677(44)3.8 × 10−6second radiation constant1.438 7752(25) × 10−2 m·K1.7 × 10−6Stefan-Boltzmann constant5.670 400(40) × 10−8 W·m−2·K−47.0 × 10−6Wien displacement law constant 4.965 114 231...2.897 7685(51) × 10−3 m · K1.7 × 10−6

 Table of adopted values 
QuantitySymbolValue (SI units)Relative Standard Uncertaintyconventional value of Josephson constant2483 597.9 × 109 Hz · V−1definedconventional value of von Klitzing constant325 812.807 Ωdefinedmolar massconstant1 × 10−3 kg · mol−1definedof carbon-1212 × 10−3 kg · mol−1definedstandard acceleration of gravity (gee, free fall on Earth)9.806 65 m·s−2definedstandard atmosphere101 325 Padefined

 মন্তব্য 
1The values are given in the so-called concise form; the number in brackets is the standard uncertainty, which is the value multiplied by the relative standard uncertainty.
2This is the value adopted internationally for realizing representations of the volt using the Josephson effect.
3This is the value adopted internationally for realizing representations of the ohm using the quantum Hall effect.

 আরও দেখুন 
 জ্যোতির্বিজ্ঞান ধ্রুবক
 বৈজ্ঞানিক ধ্রুবক (ব্যক্তির নামে নামাঙ্কিত)
 Fine-tuned universe
 Physical law
 CODATA
 আণবিক একক
 প্লাঙ্ক একক

 সহপাঠ্য 
 John D. Barrow, 2002. The Constants of Nature. Pantheon Books.

 তথ্যসূত্র 

 CODATA Recommendations - 2002 CODATA Internationally recommended values of the Fundamental Physical Constants

বিষয়শ্রেণী:পরিমাপ
বিষয়শ্রেণী:ভৌত ধ্রুবক
বিষয়শ্রেণী:ভৌত রাশি
বিষয়শ্রেণী:বৈজ্ঞানিক সূত্র