| Konstant | Symbol | Fast værdi | Bruges til at definere |
|---|---|---|---|
| Avogadros konstant | \( N_{\mathrm{A}} \) | \( N_{\mathrm{A}} = 6.022\,140\,76 \cdot 10^{23}\ \mathrm{mol^{-1}} \) | Stofmængde i mol \(\mathrm{mol}\) |
| Boltzmanns konstant | \( k \) | \( k = 1.380\,649 \cdot 10^{-23}\ \mathrm{J/K} \) | Temperatur i Kelvin \(\mathrm{K}\) |
| Elementarladningen | \( e \) | \( e = 1.602\,176\,634 \cdot 10^{-19}\ \mathrm{C} \) | strømstyrke i ampere \(\mathrm{A}\) |
| Hyperfin overgang i Cs-133 | \( \Delta \nu_{\mathrm{Cs}} \) | \( \Delta \nu_{\mathrm{Cs}} = 9\,192\,631\,770\ \mathrm{Hz} \) | tid i sekunder \(\mathrm{s}\) |
| Lysets hastighed i vakuum | \( c \) | \( c = 299\,792\,458\ \mathrm{m/s} \) | længde i meter \(\mathrm{m}\) |
| Lysudbytte (540 THz) | \( K_{\mathrm{cd}} \) | \( K_{\mathrm{cd}} = 683\ \mathrm{lm/W} \) | Lysstyrke i candela \(\mathrm{cd}\) |
| Plancks konstant | \( h \) | \( h = 6.626\,070\,15 \cdot 10^{-34}\ \mathrm{J\cdot s} \) | masse i kilogram \(\mathrm{kg}\) |
| Størrelse | Symbol | Enhed | Enheds-symbol | Eksempel |
|---|---|---|---|---|
| Elektrisk strømstyrke | \( I \) (evt. lille-\(i\)) | Ampere | \( \mathrm{A} \) | \( I = 0{,}32\,\mathrm{A} \) |
| Lysstyrke | \( I \) (intensity) | Candela | \( \mathrm{cd} \) | \( I = 10\,\mathrm{cd} \) |
| Længde | \( l \) | Meter | \( \mathrm{m} \) | \( l = 3{,}2\,\mathrm{m} \) |
| Masse | \( m \) | Kilogram | \( \mathrm{kg} \) | \( m = 48{,}9\,\mathrm{kg} \) |
| Stofmængde | \( n \) | Mol | \( \mathrm{mol} \) | \( n = 14{,}2\,\mathrm{mol} \) |
| Temperatur | \( T \) (evt. lille-\(t\)) | Kelvin | \( \mathrm{K} \) | \( T = 310\,\mathrm{K} \) |
| Tid | \( t \) | Sekunder | \( \mathrm{s} \) | \( t = 0{,}01\,\mathrm{s} \) |
| Størrelse | Symbol | Enhed | Enheds-symbol | Eksempel |
|---|---|---|---|---|
| Acceleration | \( a \) | \( \mathrm{\frac{m}{s^2}} \) | \( \mathrm{\frac{m}{s^2}} \) | \( a = 2\,\mathrm{\frac{m}{s^2}} \) |
| Aktivitet (radioaktivt stof) | \( A \) | Becquerel \( \big(\mathrm{Bq}=\mathrm{\frac{1}{s}}\big) \) | \( \mathrm{Bq} \) | \( A = 32\,\mathrm{Bq} \) |
| Areal | \( A \) eller \( T \) | \( \mathrm{m^2} \) | \( \mathrm{m^2} \) | \( A = 2{,}9\,\mathrm{m^2} \) |
| Effekt | \( P \) (power) | Watt \( \big(\mathrm{W}=\mathrm{\frac{J}{s}}\big) \) | \( \mathrm{W} \) | \( P = 200\,\mathrm{W} \) |
| Elektrisk feltstyrke | \( E \) | \( \mathrm{\frac{N}{C}} = \mathrm{\frac{V}{m}} \) | \( \mathrm{\frac{V}{m}} \) | \( E = 2\,\mathrm{\frac{V}{m}} \) |
| Elektrisk fluxtæthed | \( D \) | \( \mathrm{\frac{C}{m^2}} \) | \( \mathrm{\frac{C}{m^2}} \) | \( D = 4\,\mathrm{\frac{C}{m^2}} \) |
| Elektrisk ladning | \( Q \) | Coulomb \( \big(\mathrm{C}=\mathrm{A\cdot s}\big) \) | \( \mathrm{C} \) | \( Q = 1{,}6 \cdot 10^{-19}\,\mathrm{C} \) |
| Elektrisk spænding | \( U \) | Volt \( \big(\mathrm{V}=\mathrm{\frac{J}{C}}\big) \) | \( \mathrm{V} \) | \( U = 3{,}2\,\mathrm{V} \) |
| Energi | \( E \) | Joule \( \big(\mathrm{J}=\mathrm{kg\cdot\frac{m^2}{s^2}}\big) \) | \( \mathrm{J} \) | \( E = 1400\,\mathrm{J} \) |
| Hastighed | \( v \) | \( \mathrm{\frac{m}{s}} \) | \( \mathrm{\frac{m}{s}} \) | \( v = 3\,\mathrm{\frac{m}{s}} \) |
| Intensitet | \( I \) | \( \mathrm{\frac{W}{m^2}} \) | \( \mathrm{\frac{W}{m^2}} \) | \( I = 0{,}2\,\mathrm{\frac{W}{m^2}} \) |
| Kraft | \( F \) (force) | Newton \( \big(\mathrm{N}=\mathrm{kg\cdot\frac{m}{s^2}}\big) \) | \( \mathrm{N} \) | \( F = 380\,\mathrm{N} \) |
| Magnetisk feltstyrke | \( H \) | \( \mathrm{\frac{A}{m}} \) | \( \mathrm{\frac{A}{m}} \) | \( H = 4\,\mathrm{\frac{A}{m}} \) |
| Magnetisk fluxtæthed | \( B \) | Tesla \( \big(\mathrm{T}=\mathrm{\frac{Wb}{m^2}}\big) \) | \( \mathrm{T} \) | \( B = 2\,\mathrm{T} \) |
| Massefylde (densitet) | \( \rho \) (rho) | \( \mathrm{\frac{m}{V}} \) | \( \mathrm{\frac{kg}{m^3}} \) | \( \rho = 14\,\mathrm{\frac{kg}{m^3}} \) |
| Molmasse | \( M \) | \( \mathrm{\frac{kg}{mol}} \) | \( \mathrm{\frac{kg}{mol}} \) | |
| Permeabilitet | \( \mu \) | \( \mathrm{\frac{H}{m}} \) | \( \mathrm{\frac{H}{m}} \) | |
| Permitivitet | \( \varepsilon \) | \( \mathrm{\frac{F}{m}} \) | \( \mathrm{\frac{F}{m}} \) | |
| Tryk | \( p \) | Pascal \( \big(\mathrm{Pa}=\mathrm{\frac{N}{m^2}}\big) \) | \( \mathrm{Pa} \) | \( p = 110\,\mathrm{kPa} \) |
| Varme (energi) | \( Q \) | Joule \( \big(\mathrm{J}\big) \) | \( \mathrm{J} \) | \( Q = 30\,\mathrm{J} \) |
| Vinkel, radianer | \( \nu, \alpha, \) m.fl. | Radian \( \big(\mathrm{rad}=\mathrm{\frac{\text{buestykkelængde} m}{\text{radius} m}}=1\big) \) | \( \mathrm{rad} \) | \( \nu = 2{,}3\,\mathrm{rad} \) |
| Volumen, rumfang | \( V \) (evt. \( R \)) | \( \mathrm{m^3} \) | \( \mathrm{m^3} \) | \( V = 1{,}2\,\mathrm{m^3} \) |
| Størrelse | Symbol | Enhed | Omregning | Enheds-symbol | Eksempel |
|---|---|---|---|---|---|
| Aktivitet | \( A \) | Curie | \( 1\,\mathrm{Ci} = 3{,}7 \cdot 10^{10}\,\mathrm{Bq} \) | \( \mathrm{Ci} \) | \( 10\,\mu\mathrm{Ci} = 370\,\mathrm{kBq} \) |
| Antal | \( n \) | Enhedsløs, tælles | \(n\) | \( n = 12 \cdot 10^{14} \) | |
| Atommasse-enhed | \( m \) | Unit/Dalton | \( 1\,\mathrm{u} = 1{,}660\,539\,066\,60 \cdot 10^{-27}\,\mathrm{kg} \) | \( \mathrm{u} \) |
\( m_p = 1{,}007276\,\mathrm{u} \) \( m_n = 1{,}008665\,\mathrm{u} \) \( m_e = 0{,}0005447\,\mathrm{u} \) |
| Effekt | \( P \) | Hestekræfter | \( 1\,\mathrm{HK} = 735{,}3\,\mathrm{W} \) | \( \mathrm{HK} \) | \( 115\,\mathrm{HK} \approx 84{,}6\,\mathrm{kW} \) |
| Energi | \( E \) | Elektronvolt | \( 1\,\mathrm{eV} = 1{,}602176 \cdot 10^{-19}\,\mathrm{J} \) | \( \mathrm{eV} \) | \( E_{\mathrm{foton}} = 8\,\mathrm{eV} \) |
| Energi | \( E \) | Kilowatt-time | \( 1\,\mathrm{kWh} = 3{,}6\,\mathrm{MJ} \) | \( \mathrm{kWh} \) | \( E_{\mathrm{dag}} = 10\,\mathrm{kWh} \) |
| Hastighed | \( v \) | Kilometer i timen | \( 1\,\mathrm{\frac{km}{t}} = \frac{10}{36}\,\mathrm{\frac{m}{s}} \) | \( \mathrm{\frac{km}{t}} \) | \( v = 80\,\mathrm{\frac{km}{t}} \) |
| Masse | \( m \) | Ton | \( 1\,\mathrm{ton} = 1000\,\mathrm{kg} \) | \( \mathrm{ton} \) | \( m = 3{,}4\,\mathrm{ton} \) |
| Temperatur | \( T \) | Grader Celsius | \( 20^\circ\mathrm{C} = (20 + 273{,}15)\,\mathrm{K} \) (Kelvin) | \( {}^\circ\mathrm{C} \) | \( T = 20^\circ\mathrm{C} \) |
| Tryk | \( p \) | Bar | \( 1\,\mathrm{bar} = 100\,\mathrm{kPa} \) | \( \mathrm{bar} \) | \( 3\,\mathrm{bar} = 300\,\mathrm{kPa} \) |
| Tryk | \( p \) | Atmosfære | \( 1\,\mathrm{atm} = 101{,}325\,\mathrm{kPa} \) | \( \mathrm{atm} \) | \( 2\,\mathrm{atm} = 202{,}65\,\mathrm{kPa} \) |
| Tryk | \( p \) | \( \mathrm{psi} \) | \( 1\,\mathrm{psi} = 6794{,}757293\,\mathrm{Pa} \) | \( \mathrm{psi} \) | \( p = 32\,\mathrm{psi} \) |
| Vinkelmål | \( \nu, \alpha, \) m.fl. | Grader | \( 360^\circ = 2\pi\,\mathrm{rad} \) | \( {}^\circ \) | \( \nu = 220^\circ \) |
| Volumen | \( V \) (,\( R \)) | Liter | \( 1000\,\mathrm{L} = 1\,\mathrm{m^3} \) | \( \mathrm{L} \) | \( V = 3{,}5\,\mathrm{L} \) |
| Konstant | Værdi | Konstant | Værdi |
|---|---|---|---|
| Gaskonstanten \( R \) | \( 8.314\,462\,618\ \mathrm{J/(mol\cdot K)} \) | Tyngdeacceleration \( g_0 \) | \( 9.806\,65\ \mathrm{m/s^2} \) |
| Gravitationskonstant \( G \) | \( 6.674\,30\cdot 10^{-11}\ \mathrm{m^3/(kg\cdot s^2)} \) | Vakuumpermittivitet \( \varepsilon_0 \) | \( 8.854\,187\,8128\cdot 10^{-12}\ \mathrm{F/m} \) |
| Vakuumpermeabilitet \( \mu_0 \) | \( 1.256\,637\,062\cdot 10^{-6}\ \mathrm{H/m} \) | Coulombs konstant \( k_e \) | \( 8.987\,551\,7923\cdot 10^{9}\ \mathrm{N\,m^2/C^2} \) |
| Potens | Præfiks | Symbol | Potens | Præfiks | Symbol | Potens | Præfiks | Symbol |
|---|---|---|---|---|---|---|---|---|
| \(10^{-18}\) | atto | \( \mathrm{a} \) | \(10^{-15}\) | femto | \( \mathrm{f} \) | \(10^{-12}\) | piko | \( \mathrm{p} \) |
| \(10^{-9}\) | nano | \( \mathrm{n} \) | \(10^{-6}\) | mikro | \( \mathrm{\mu} \) | \(10^{-3}\) | milli | \( \mathrm{m} \) |
| \(10^{-2}\) | centi | \( \mathrm{c} \) | \(10^{-1}\) | deci | \( \mathrm{d} \) | \(10^{0}\) | (ingen) | – |
| \(10^{3}\) | kilo | \( \mathrm{k} \) | \(10^{6}\) | mega | \( \mathrm{M} \) | \(10^{9}\) | giga | \( \mathrm{G} \) |
| \(10^{12}\) | tera | \( \mathrm{T} \) | \(10^{15}\) | peta | \( \mathrm{P} \) | \(10^{18}\) | exa | \( \mathrm{E} \) |