Why is current a fundamental quantity and not charge?

Answer 1

SI has a set of base units, which are all from the metric system but are chosen to give consistency:

Length in meters, mass in kilograms, time in seconds, temperature in degrees kelvin, electric current in amperes, amount of substance in moles, luminous intensity in candelas.

Previously, scientists used to use the CGS system, which stands for centimeter gram second, and engineers used to use MKS which stands for meter kilogram second, largely because engineers were used to larger quantities. Now it is more unified. Scientists used to use as force the dyne, now we use the Newton, and for work the erg, now we use the joule. For speed we use meters/sec instead of centimeters/sec. For pressure the SI unit is the pascal which is 1 Newton /sq meter, whereas scientists used to use dynes/sq cm, and engineers often used kg/sq cm.

All these SI units can be called metric, and they are all related to the earlier metric system, but using consistent units makes it easier to compare work done in different countries and disciplines.

Answer 2

The SI does not define 'fundamental quantity', instead it uses the term 'Base Unit'. All other units are 'Derived Units', so-called because they are each derived from combinations of Base Units.

The ampere is a Base Unit, and is defined in terms of the force between two, parallel, current carrying conductors. This definition is important, because it makes use of one of the three effects of an electric current (electromagnetism) to enable it to be measured with great accuracy. Furthermore, it is the unit by which electrical units are linked to mechanical units. If you like, the ampere is the 'bridge' between 'mechanical' units and 'electrical units', which makes it very important.

Because the ampere is easily measured, and is a Base Unit, it makes sense for the coulomb (a Derived Unit) to be defined in terms of the ampere and the second, and not the other way around! For this reason, the ampere is considered to be more fundamental than the coulomb.

For the purposes of pedagogy, some (in my view, misguided) teachers like to define the ampere in terms of a coulomb per second. But the question has to be asked, 'How do you measure a coulomb?'; the answer is that you cannot, except in terms of the ampere (and the second). So, while an ampere is most certainly 'equivalent' to a coulomb per second, it cannot be defined in this way.

Answer 3

We measure current in amperes or amps.

Answer 4

the fundamental unit of the current is the amper (A) ,and the amper is fundamental unit since it cant be produce from another units

Answer 5

Amperes (abbreviated as Amps, symbol = A)

Answer 6

since it is one of the physical quantites