# Formula Symbols - E

on . Posted in Nomenclature & Symbols for Engineering, Mathematics, and Science

## Formula Symbols

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## E

SymbolGreek SymbolDefinitionEnglishMetricSIValue
-  - earth age $$sec$$ $$s$$ $$s$$ $$1.4327\;(14)\;x\;10^{17}$$ $$s$$
-  - earth axial tilt $$deg$$ $$rad$$ $$rad$$ $$0.407\;638\;19$$ $$rad$$
-  - earth average lunar month $$sec$$ $$s$$ $$s$$ $$2.551\;4430\;(5)\;x\;10^{6}$$
-  - earth core radius $$ft$$ $$m$$ $$m$$ $$3.485\;x\;10^6$$ $$m$$
-  - earth dry land surface area $$ft^2$$ $$m^2$$ $$m^2$$ $$1.489\;40\;x\;10^{14}$$ $$m^2$$
-  - earth equatorial surface gravity $$\large{\frac{ft}{sec^2}}$$ $$\large{\frac{m}{s^2}}$$ $$m-s^{-2}$$ $$9.780\;327$$ $$\large{\frac{m}{s^2}}$$
-  - earth equatorial radius $$ft$$ $$m$$ $$m$$ $$6.3781\;x\;10^6$$ $$m$$
-  - earth equatorial rotation speed $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$ $$465.1$$ $$\large{\frac{m}{s}}$$
-  - earth escape velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$ $$1.1186\;x\;10^4$$ $$\large{\frac{m}{s}}$$
- - earth mass $$lbm$$ $$kg$$ $$kg$$ $$5.9736\;x\;10^{24}$$ $$kg$$
-  - earth mean density $$\large{\frac{lbm}{ft^3}}$$ $$\large{\frac{kg}{m^3}}$$  $$kg-m^{-3}$$ $$5.515\;x\;10^3$$ $$\large{\frac{kg}{m^3}}$$
- - earth mean orbit velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$ $$2.9780\;10^4$$ $$\large{\frac{m}{s}}$$
-  - earth mean surface pressure $$\large{\frac{lbf}{in^2}}$$ $$\large{\frac{kg}{m-s^2}}$$  $$kg-m^{-1}-s^{-2}$$ $$1.103\;25\;10^5$$ $$\large{\frac{kg}{m-s^2}}$$
-  - earth mean radius $$ft$$ $$m$$ $$m$$ $$6.3710\;x\;10^6$$ $$m$$
-  - earth mean surface temperature $$F$$ $$K$$ $$x-273.15\;C$$ -
-  - earth molar mass constant $$\large{\frac{lbm}{mol}}$$ $$\large{\frac{kg}{mol}}$$ $$kg-mol^{-1}$$ $$0.001$$ $$\large{\frac{kg}{mol}}$$
-  - earth polar radius $$ft$$ $$m$$ $$m$$ $$6.3568\;x\;10^6$$ $$m$$
- - earth semi-major orbital axis $$ft$$ $$m$$ $$m$$ $$1.495\;982\;61\;10^{11}$$ $$m$$
-  - earth surface area $$ft^2$$ $$m^2$$ $$m^2$$ $$5.100\;720\;x\;10^{14}$$ $$m^2$$
-  - earth volume $$ft^3$$ $$m^3$$ $$m^3$$ $$1.083\;21\;x\;10^{21}$$ $$m^3$$
$$A_c$$ - earthwork cross-section area $$ft^2$$ $$m^2$$ $$m^2$$ -
$$V$$ - earthwork cross-section volume $$ft^3$$ $$m^3$$ $$m^3$$ -
$$e$$ - eccentricity $$in$$ $$mm$$ $$mm$$  -
$$Ec$$ - Eckert number dimensionless  -
$$I$$ - effective line current $$I$$ $$I$$ $$C - s^{-1}$$   -
$$V$$ - effective line voltage $$V$$ $$V$$ $$kg-m^2-s^{-3}-A^{-1}$$   -
$$D_e$$ - effective diffusivity $$\large{ \frac{ft^2}{sec} }$$ $$\large{ \frac{m^2}{s} }$$ $$m^2-s^{-1}$$  -
$$D_{eff}$$ - effective diffusivity coefficient - - - -
$$m*_n$$, $$\;m*_p$$ - effective mass - - -  -
$$A$$ - effective mass transfer area $$ft^2$$ $$m^2$$ $$m^2$$  -
$$\eta$$ eta efficiency dimensionless  -
$$\Theta_e$$ Theta Einstein temperature - - -  -
$$Ek$$ - Ekman number dimensionless  -
$$E$$ - elastic - -    -
$$\lambda$$ lambda elastic modulus $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$  -
$$\lambda_c$$, $$\;E_c$$ lambda elastic modulus of concrete $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$\mu_0$$ mu electric permittivity vacuum - $$\large{\frac{F}{m}}$$ $$F-m^{-1}$$ $$8.854\;187\;8128\;(13)\;x\;10^{-12}$$ $$\large{\frac{F}{m}}$$
$$PE$$, $$\;E_p$$ - elastic potential energy $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$S$$ - elastic section modulus $$\large{in^3}$$ $$\large{mm^3}$$ $$\large{mm^3}$$  -
$$E$$ - elasticity - - -  -
$$El$$ - elasticity number dimensionless  -
$$q$$ - electric charge $$C$$ $$A-s$$ $$A-s$$  -
$$\rho$$ rho electric charge density $$\large{\frac{A-sec}{ft^3}}$$ $$\large{\frac{C}{m^3}}$$ $$C-m^{-3}$$ -
$$F$$ - electric capacitance - - -  -
$$S$$ - electric conductance - - -  -
$$\sigma$$ sigma electric conductivity - $$\large{\frac{S}{m}}$$ $$A^2-s^3-kg^{-1}-m^{-3}$$ -
$$\rho_{ik}$$ rho electric conductivity tensor - - -  -
$$\varepsilon_0$$ varepsilon electric constant - $$\large{\frac{F}{m}}$$ $$F-m^{-1}$$ $$8.8542\;x\;10^{-12}$$ $$\large{\frac{F}{m}}$$
$$I$$ - electric current $$I$$ $$\large{\frac{C}{s}}$$ $$C - s^{-1}$$  -
$$J$$ - electric current density - $$\large{\frac{A}{m^2}}$$ $$A - m^{-2}$$  -
$$p$$ - electric dipole moment - - -  -
$$D$$ - electric displacement - - -  -
$$E$$ - electric field - $$\large{\frac{V}{m}}$$ $$V-m^{-1}$$  -
- - electric field density - - - -
$$E$$ - electric field strength - $$\large{\frac{V}{m}}$$ $$V-m^{-1}$$ -
$$\psi$$ psi electric flux - -    -
$$D$$ - electric flux density   $$\large{\frac{C}{m^2}}$$ $$C-m^{-2}$$ -
$$V$$, $$\;\phi$$ phi electric potential - - -  -
$$U_e$$ - electric potential energy - - -  -
$$P$$ - electric power $$W$$ $$\large{\frac{kg-m^2}{s^3}}$$  $$kg-m^2-s^{-3}$$  -
$$\Omega$$ Omega electric resistance $$\Omega$$ $$\large{\frac{kg-m^2}{s^3-A^2}}$$  $$kg-m^2-s^{-3}-A^{-2}$$  -
$$\rho$$ rho electric resistivity - - - -
$$X_c$$ - electric susceptibility - - -  -
$$V$$ - elrctric voltage $$V$$ $$\large{\frac{kg-m^2}{s^{3}-A}}$$  $$kg-m^2-s^{-3}-A^{-1}$$ -
$$EM$$ - electromagnetic energy - - - -
$$e$$ - electron - - -  -
$$E_{ea}$$ - electron affinity - - -  -
$$e$$ - electron charge $$A-sec$$ $$C$$ $$A-s$$ -
$$Qm$$ - electron mass-to-charge ratio $$A-sec$$ $$C$$ $$A-s$$ $$1.602\;x\;10^{-19}$$ $$C$$
$$D_e$$ - electron diffusion coefficient - - -  -
$$a_{ge}$$ - electron gravitational coupling constant dimensionless constant $$2.40\;x\;10^{-43}$$
$$E_e$$ - electron rest energy $$\large{\frac{lbm-ft^2}{sec}}$$ $$J$$ $$kg-m^2-s^{-2}$$ $$8.187\;105\;\;06\;(36)\;x\;10^{-14}$$ $$J$$
$$g_e$$ - electron g-factor dimensionless constant $$-2.002\;319\;304\;362\;56\;(35)$$
$$m_e$$ - electron mass $$lbm$$ $$kg$$ $$kg$$ $$9.109\;383\;7015(28)\;x\;10^{-31}$$ $$kg$$
$$m_c$$  - electron molar charge $$\large{\frac{A-sec}{mol}}$$ $$\large{\frac{C}{mol}}$$  $$C-mol^{-1}$$ $$-9.648\;533\;65\;(21)\;x\;10^{4}$$ $$\large{\frac{C}{mol}}$$
$$M \left( e \right)$$, $$\;M_e$$ - electron molar mass $$\large{\frac{lbm}{mol}}$$ $$\large{\frac{kg}{mol}}$$  $$kg-mol^{-1}$$  $$5.485\;799\;0946\;(22)\;x\;10^{-7}$$ $$\large{\frac{kg}{mol}}$$
$$n$$, $$\;n_n$$, $$\;n^{12}$$ - electron number density - - -  -
$$g_\lambda$$ lambda electron orbital g-factor dimensionless constant $$0.993\;643\;364$$
$$O_e$$ - electron outer shell multiplier dimensionless constant $$2.138\;743\;820$$
$$K_e$$ - electron partical wave center point dimensionless constant $$10$$
$$w_{pe}$$ - electron plasma circular frequency - - -  -
$$\frac {m_c}{m_p}$$ - electron-proton mass ratio dimensionless constant $$5.446\;170\;2178\;x\;10^{-4}$$
$$r_e$$ - electron radius $$ft$$ $$m$$ $$m$$ $$2.817\;940\;3262\;x\;10^{-15}$$ $$m$$
$$m_e$$ - electron rest mass $$lbm$$ $$kg$$ $$kg$$ $$9.109\;382\;\;91\;(40)\;x\;10^{-31}$$ $$kg$$
$$\frac {-e}{m_e}$$ - electron specific charge - - -  -
$$g_a$$ - electron spin g-factor dimensionless constant $$0.976\;448\;541$$
$$T_e$$ - electron temperature - - -  -
$$e$$ - electronic charge - - -  -
$$u \;or\; w$$ - electromagnetic energy density - - -  -
$$E$$, $$\;\varepsilon$$ varepsilon electromotive force (EMF) - - -  -
$$F_e$$ - electrostatic force $$lbf$$ $$N$$  $$kg-m-s^{-2}$$  -
$$e$$, $$\;q_e$$ - elementary change - $$C$$ $$A-s$$ $$1.602\;176\;634\;x\;10^{-19}$$ $$C$$
$$y$$ - elevation $$ft$$ or $$in$$ $$$m$$ or $$mm$$ $$m$$ or $$mm$$ - $$y_i$$ - elevation at inlet $$ft$$ or $$in$$$$$m$$ or $$mm$$ $$m$$ or $$mm$$  -
$$y_o$$  - elevation at outlet $$ft$$ or $$in$$ $$$m$$ or $$mm$$ $$m$$ or $$mm$$ - $$\Delta y$$ Delta elevation differential $$ft$$ or $$in$$$$$m$$ or $$mm$$ $$m$$ or $$mm$$  -
$$E$$ - elongation $$ft$$ or $$in$$ \$$$m$$ or $$mm$$ $$m$$ or $$mm$$ -
$$E_p$$ - elongation percentage dimensionless -
$$E$$ - emission rate $$\large{\frac{lbf}{hr}}$$ $$\large{\frac{kg}{h}}$$ $$kg-h^{-1}$$ -
$$\epsilon$$ epsilon emissivity $$F$$ $$C$$ $$A-s$$  -
$$\epsilon$$ epsilon emissivity of the material $$F$$ $$C$$ $$A-s$$  -
$$E$$ - emissive power $$\large{\frac{Btu}{ft^2-hr}}$$ $$\large{\frac{W}{m^2}}$$ $$W-m^{-2}$$   -
$$\gamma$$ gamma empirical constant $$\large{\frac{1}{hr}}$$ $$\large{\frac{1}{s}}$$ $$m$$ or $$mm$$  -
$$\epsilon$$ epsilon empirical loss coefficient dimensionless  -
$$r$$ - empirical rate $$\large{\frac{1}{hr}}$$ $$\large{\frac{1}{s}}$$ $$1-s^{-1}$$  -
$$r$$ - empirical rate constant $$\large{\frac{1}{hr}}$$ $$\large{\frac{1}{s}}$$ $$1-s^{-1}$$ -
$$E$$, $$\;W$$ - energy $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$\Delta E$$ - energy differential $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$EER$$ - energy efficiency rating or ratio dimensionless  -
$$\epsilon$$ epsilon energy of particle $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$E_g$$ - energy gap $$lbf-ft$$ $$J$$ $$kg-m^2-s^{-2}$$  -
$$E$$ - energy usage (usage) $$kW-hr$$ $$kW-h$$ $$kW-h$$   -
$$EHP$$, $$\;HP_e$$ - engine horsepower $$\large{\frac{lbf-ft}{sec}}$$ $$\large{\frac{Btu}{s}}$$ $$Btu-s^{-1}$$ -
$$RPM$$ - engine speed $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$H$$ - enthalpy $$\large{\frac{Btu}{lbm}}$$ $$\large{\frac{kJ}{kg}}$$ $$kJ-kg^{-1}$$  -
$$\large{ \partial H }$$ partial enthalpy rate of change - - - -
$$S$$ - entropy $$\large{\frac{Btu}{lbm-R}}$$ $$\large{\frac{kJ}{kg-K}}$$ $$kJ-kg^{-1}-K^{-1}$$  -
$$\Delta S$$ Delta entropy differential $$\large{\frac{Btu}{lbm-R}}$$ $$\large{\frac{kJ}{kg-K}}$$ $$kJ-kg^{-1}-K^{-1}$$  -
$$\phi$$ phi entropy function - - -  -
$$Eo$$ - Eotvos number dimensionless  -
$$x$$ - equilibrium $$in$$ $$mm$$ $$mm$$ -
$$K$$ - equilibrium constant - - -  -
$$EW$$ - equivalent weight  $$\large{\frac{lbm}{lbmol}}$$

$$\large{\frac{kg}{kmol}}$$

$$kg-kmol^{-1}$$  -
$$Er$$ - Ericksen number dimensionless -
$$v_e$$ - escape velocity $$\large{\frac{ft}{sec}}$$ $$\large{\frac{m}{s}}$$ $$m-s^{-1}$$  -
$$A$$ - estimated annual soil loss $$tons-acre-yr$$ $$tonnes-hectare-yr$$ $$tonnes-hectare-yr$$ -
$$A_e$$, $$\;P_e$$ - Ettinghausen coefficient - - -  -
$$Eu$$ - Euler number dimensionless constant  $$2.718\;281\;828\;459...$$
$$\Delta h_f$$ Delta evaporation enthalpy change - - -  -
$$\Theta_r$$ Theta excess temperature coefficient dimensionless  -
$$Q$$ - exchanged heat in a heat exchanger $$\large{ \frac{Btu}{lbm}}$$ $$\large{ \frac{kJ}{kg}}$$ $$kJ-kg^{-1}$$ -
$$Y$$ - expansion coefficient $$\large{ \frac{in}{in-F} }$$ $$\large{ \frac{mm}{mm-C} }$$ $$mm-mm^{-1}-C^{-1}$$  -
$$Y$$ - expansion factor dimensionless  -
$$\tau$$ tau exponential time constant $$sec$$ $$s$$ $$s$$  -
$$p_e$$ - external pressure $$\large{\frac{lbf}{in^2}}$$ $$Pa$$ $$kg-m^{-1}-s^{-2}$$ -
$$r_e$$ - external radius $$in$$ $$mm$$ $$mm$$ -
Symbol Greek Symbol Definition English Metric   Value

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