Question

An electric current is the rate of flow of electric charges and it is measured in ampere.
A) True
B) False

Answer 1

Hint: The electric current flowing through a conductor is often defined as the quantity of electric charge flowing across the cross section of the conductor in one second. The SI unit of electric current is Ampere.

Complete step-by-step answer:
When electrons flow across a cross section of a conductor, they are in essence, carrying a certain quantity of electric charge across the cross section (since electrons are the fundamental negative charge carriers). This results in the net flow of charge across the cross section of the conductor.
The amount of net electric charge flowing across a cross section of the conductor per second is defined as the electric charge flowing across the conductor. The magnitude of electric current is given by
$I=\dfrac{q}{t}$ where I is the current, q is the net charge flowing across the cross section and t is the time interval in which the charge is flowing.
$\therefore I=\dfrac{ne}{t}$ --$\left( \because q=ne \right)$ where n is the number of electrons flowing across the cross section and e is magnitude of the charge carried by an electron. $e=1.6\times {{10}^{-19}}C$
However, the direction of current is taken opposite to the direction of flow of electrons, since in earlier times, it was believed that current was created by positively charged particles. This is wrong, however, the convention for the direction of electric current stood.
The SI unit of electric current is Ampere (A). 1 Ampere is the electric current constituted by a charge of 1 coulomb flowing across the cross section of a conductor per second. That is,
$1\text{ Ampere = }\dfrac{\text{1 Coulomb}}{1\text{ second}}$ $\therefore 1A=1C.{{s}^{-1}}$
Hence, the given statement is true. So, the correct option is A) true.

Note: Electric current is regarded as a fundamental quantity in many systems of measurement and specifically the SI system which is the universally recognized system of measurements for all scientific purposes.
Knowing the definition of physical quantities along with the names of their different units (especially SI unit) is imperative for solving such questions. A student must be thorough with his knowledge of the physical quantities (especially the fundamental quantities) and their units since they become the basis for all further studies of physics.