Physlib.Units.ISQDimensionBase
The ISQ base quantities
The International System of Quantities (ISQ), specified in ISO/IEC 80000-1 and described in the International Vocabulary of Metrology (VIM, 3rd edition, JCGM 200:2012), fixes seven mutually independent *base quantities*: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
`ISQDimensionBase` is that seven-element basis, realised as an instantiation `Dimension ISQDimensionBase` of the parametric dimensional algebra. It differs from PhysLib's default `LTMCTDimensionBase` in two ways:
* the electromagnetic base quantity is *electric current*, so electric charge is a *derived* dimension (`Q = I · T`, `ISQDimensionBase.charge`); and * *amount of substance* and *luminous intensity* are additional independent base quantities.
References
* ISO/IEC 80000-1:2009, *Quantities and units — Part 1: General*. * JCGM 200:2012, *International vocabulary of metrology — Basic and general concepts and associated terms (VIM, 3rd edition)*.
10 declarations
The seven ISQ base quantities
The type `ISQDimensionBase` is an inductive set representing the seven fundamental base quantities of the International System of Quantities (ISQ), as defined in ISO/IEC 80000-1 and the International Vocabulary of Metrology (VIM). These seven mutually independent quantities are: 1. Length () 2. Mass () 3. Time () 4. Electric current () 5. Thermodynamic temperature () 6. Amount of substance () 7. Luminous intensity () In this system, electric current is treated as a base quantity, making electric charge a derived quantity (). This distinguishes it from systems that use charge as a base dimension.
Equality in is decidable
For any two base quantities in the set of International System of Quantities base dimensions (), it is decidable whether . The set contains the seven fundamental quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.
is a finite set
The type , which represents the seven fundamental base quantities of the International System of Quantities (length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity), is a finite set.
The cardinality of is
The International System of Quantities (ISQ) base dimensions set, denoted as , consists of seven mutually independent base quantities: length (), mass (), time (), electric current (), thermodynamic temperature (), amount of substance (), and luminous intensity (). This theorem states that the cardinality (number of elements) of is equal to .
Electric charge dimension
In the International System of Quantities (ISQ), the dimension of electric charge is defined as a derived dimension. It is the product of the base dimension of electric current and the base dimension of time . Mathematically, this is expressed as .
The electric current exponent of charge is
In the International System of Quantities (ISQ), the exponent of the electric current base dimension in the derived dimension of electric charge is equal to .
The exponent of time in the dimension of electric charge is
In the International System of Quantities (ISQ), the exponent of the base dimension of time () in the derived dimension of electric charge () is equal to .
The mass exponent of electric charge is
In the International System of Quantities (ISQ), the exponent of the base dimension of mass in the derived dimension of electric charge is .
Amount of substance
In the International System of Quantities (ISQ), the dimension corresponding to the amount of substance is not equal to the dimensionless identity . Here, the amount of substance is one of the seven independent base quantities, and represents the dimension where all base quantity exponents are zero.
Luminous intensity is not dimensionless ()
In the International System of Quantities (ISQ), the dimension corresponding to the base quantity of luminous intensity, denoted as , is not equal to the dimensionless identity . This confirms that luminous intensity is an independent base dimension in the ISQ framework and cannot be represented as a dimensionless quantity.
