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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

inductive

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 (LL) 2. Mass (MM) 3. Time (TT) 4. Electric current (II) 5. Thermodynamic temperature (Θ\Theta) 6. Amount of substance (NN) 7. Luminous intensity (JJ) In this system, electric current is treated as a base quantity, making electric charge a derived quantity (Q=ITQ = I \cdot T). This distinguishes it from systems that use charge as a base dimension.

instance

Equality in ISQDimensionBase\text{ISQDimensionBase} is decidable

For any two base quantities q1,q2q_1, q_2 in the set of International System of Quantities base dimensions (ISQDimensionBase\text{ISQDimensionBase}), it is decidable whether q1=q2q_1 = q_2. The set ISQDimensionBase\text{ISQDimensionBase} contains the seven fundamental quantities: length, mass, time, electric current, thermodynamic temperature, amount of substance, and luminous intensity.

instance

ISQDimensionBase\text{ISQDimensionBase} is a finite set

The type ISQDimensionBase\text{ISQDimensionBase}, 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.

theorem

The cardinality of ISQDimensionBase\text{ISQDimensionBase} is 77

The International System of Quantities (ISQ) base dimensions set, denoted as ISQDimensionBase\text{ISQDimensionBase}, consists of seven mutually independent base quantities: length (LL), mass (MM), time (TT), electric current (II), thermodynamic temperature (Θ\Theta), amount of substance (NN), and luminous intensity (JJ). This theorem states that the cardinality (number of elements) of ISQDimensionBase\text{ISQDimensionBase} is equal to 77.

definition

Electric charge dimension Q=ITQ = I \cdot T

In the International System of Quantities (ISQ), the dimension of electric charge QQ is defined as a derived dimension. It is the product of the base dimension of electric current II and the base dimension of time TT. Mathematically, this is expressed as Q=ITQ = I \cdot T.

theorem

The electric current exponent of charge QQ is 11

In the International System of Quantities (ISQ), the exponent of the electric current base dimension in the derived dimension of electric charge QQ is equal to 11.

theorem

The exponent of time in the dimension of electric charge is 11

In the International System of Quantities (ISQ), the exponent of the base dimension of time (TT) in the derived dimension of electric charge (QQ) is equal to 11.

theorem

The mass exponent of electric charge QQ is 00

In the International System of Quantities (ISQ), the exponent of the base dimension of mass MM in the derived dimension of electric charge QQ is 00.

theorem

Amount of substance 1\neq 1

In the International System of Quantities (ISQ), the dimension corresponding to the amount of substance is not equal to the dimensionless identity 11. Here, the amount of substance is one of the seven independent base quantities, and 11 represents the dimension where all base quantity exponents are zero.

theorem

Luminous intensity is not dimensionless (single(J)1\text{single}(J) \neq 1)

In the International System of Quantities (ISQ), the dimension corresponding to the base quantity of luminous intensity, denoted as single(luminousIntensity)\text{single}(\text{luminousIntensity}), is not equal to the dimensionless identity 11. This confirms that luminous intensity is an independent base dimension in the ISQ framework and cannot be represented as a dimensionless quantity.