Why is charge a derived quantity

• mc2_phy
In summary, charge is considered a derived quantity because it is measured in Coulombs or Amperes seconds, and is derived from the fundamental unit of current. This is because it is easier to measure current precisely than it is to measure charge precisely. The seven base units in SI include meter, kilogram, second, ampere, kelvin, candela, and mole.
mc2_phy
Why is charge a derived quantity?

convention. Current was measured before charge.

There are seven base units from which all other units are derived.

-meter (length)
-kilogram (mass)
-second (time)
-ampere (electric current)
-kelvin (temperature)
-candela (luminous intensity)
-mole (concentration of substance)

Electric charge is measured in Coulombs, or Amperes seconds.

Last edited:
In SI, current is a fundamental unit (ampere) and charge is a derived unit (coulomb = ampere · second) for practical reasons. It's easier to implement the standard for current precisely, by measuring the force between two current-carrying wires, than it would be to implement a standard for charge precisely, involving something like measuring the force between two charges, or counting electrons.

AbsoluteZer0 said:
Electric charge is measured in Coulombs, or Amperes per second.
Ampere seconds, not amperes per second.

AlephZero said:
Ampere seconds, not amperes per second.

My apologies.
Edited and corrected.

No prob. Thanks for that. Really cleared it up

1. Why is charge considered a derived quantity?

Charge is considered a derived quantity because it is not a fundamental physical property like mass or length. Instead, it is defined in terms of other fundamental quantities, such as electric current and voltage, through the equation Q = I * t.

2. What are the fundamental quantities that charge is derived from?

The fundamental quantities that charge is derived from are electric current and voltage. Electric current is the rate at which electric charge flows, and voltage is the measure of electric potential difference between two points.

3. How is charge measured?

Charge is measured in units called coulombs (C). One coulomb is equal to the amount of charge transferred by a current of one ampere in one second.

4. Why is charge important in science?

Charge is important in science because it is a fundamental property of matter and is the basis for many physical phenomena, such as electricity, magnetism, and chemical bonding. Understanding charge allows scientists to explain and predict the behavior of particles and systems.

5. Can charge be created or destroyed?

In most cases, charge cannot be created or destroyed. According to the law of conservation of charge, the total amount of charge in a closed system remains constant. However, charge can be transferred from one object to another through various processes, such as charging by friction or conduction.

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