(maxima.info)Introduction to physical_constants
57.2 Introduction to physical_constants
=======================================
'physical_constants' is a collection of physical constants, copied from
CODATA 2006 recommended values (<http://physics.nist.gov/constants>).
'load ("physical_constants")' loads this package, and loads 'ezunits'
also, if it is not already loaded.
A physical constant is represented as a symbol which has a property
which is the constant value. The constant value is a dimensional
quantity, as represented by 'ezunits'. The function 'constvalue'
fetches the constant value; the constant value is not the ordinary value
of the symbol, so symbols of physical constants persist in evaluated
expressions until their values are fetched by 'constvalue'.
'physical_constants' includes some auxiliary information, namely, a
description string for each constant, an estimate of the error of its
numerical value, and a property for TeX display. To identify physical
constants, each symbol has the 'physical_constant' property;
'propvars(physical_constant)' therefore shows the list of all such
symbols.
'physical_constants' comprises the following constants.
'%c'
speed of light in vacuum
'%mu_0'
magnetic constant
'%e_0'
electric constant
'%Z_0'
characteristic impedance of vacuum
'%G'
Newtonian constant of gravitation
'%h'
Planck constant
'%h_bar'
Planck constant
'%m_P'
Planck mass
'%T_P'
Planck temperature
'%l_P'
Planck length
'%t_P'
Planck time
'%%e'
elementary charge
'%Phi_0'
magnetic flux quantum
'%G_0'
conductance quantum
'%K_J'
Josephson constant
'%R_K'
von Klitzing constant
'%mu_B'
Bohr magneton
'%mu_N'
nuclear magneton
'%alpha'
fine-structure constant
'%R_inf'
Rydberg constant
'%a_0'
Bohr radius
'%E_h'
Hartree energy
'%ratio_h_me'
quantum of circulation
'%m_e'
electron mass
'%N_A'
Avogadro constant
'%m_u'
atomic mass constant
'%F'
Faraday constant
'%R'
molar gas constant
'%%k'
Boltzmann constant
'%V_m'
molar volume of ideal gas
'%n_0'
Loschmidt constant
'%ratio_S0_R'
Sackur-Tetrode constant (absolute entropy constant)
'%sigma'
Stefan-Boltzmann constant
'%c_1'
first radiation constant
'%c_1L'
first radiation constant for spectral radiance
'%c_2'
second radiation constant
'%b'
Wien displacement law constant
'%b_prime'
Wien displacement law constant
Reference: <http://physics.nist.gov/constants>
Examples:
The list of all symbols which have the 'physical_constant' property.
(%i1) load ("physical_constants")$
(%i2) propvars (physical_constant);
(%o2) [%c, %mu_0, %e_0, %Z_0, %G, %h, %h_bar, %m_P, %T_P, %l_P,
%t_P, %%e, %Phi_0, %G_0, %K_J, %R_K, %mu_B, %mu_N, %alpha,
%R_inf, %a_0, %E_h, %ratio_h_me, %m_e, %N_A, %m_u, %F, %R, %%k,
%V_m, %n_0, %ratio_S0_R, %sigma, %c_1, %c_1L, %c_2, %b, %b_prime]
Properties of the physical constant '%c'.
(%i1) load ("physical_constants")$
(%i2) constantp (%c);
(%o2) true
(%i3) get (%c, description);
(%o3) speed of light in vacuum
(%i4) constvalue (%c);
m
(%o4) 299792458 ` -
s
(%i5) get (%c, RSU);
(%o5) 0
(%i6) tex (%c);
$$c$$
(%o6) false
The energy equivalent of 1 pound-mass. The symbol '%c' persists
until its value is fetched by 'constvalue'.
(%i1) load ("physical_constants")$
(%i2) m * %c^2;
2
(%o2) %c m
(%i3) %, m = 1 ` lbm;
2
(%o3) %c ` lbm
(%i4) constvalue (%);
2
lbm m
(%o4) 89875517873681764 ` ------
2
s
(%i5) E : % `` J;
Computing conversions to base units; may take a moment.
366838848464007200
(%o5) ------------------ ` J
9
(%i6) E `` GJ;
458548560580009
(%o6) --------------- ` GJ
11250000
(%i7) float (%);
(%o7) 4.0759872051556356e+7 ` GJ
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