Question

1 ampere current is equivalent to
A. $6.25\times {{10}^{18}}$ electrons per sec.
B. $2.25\times {{10}^{18}}$ electrons per sec.
C. $6.25\times {{10}^{14}}$ electrons per sec.
D. $2.25\times {{10}^{14}}$ electrons per sec.

Answer 1

Electric current is equal to the amount of charge flowing through a cross section per unit time. 1 ampere of current is equal to a charge of 1 coulomb flowing in 1 second. We can associate current with the number of electrons flowing per second. For this, calculate the number of electrons that make a charge of 1 coulomb.

Complete step by step answer:
Electric current is defined as the amount of charge flowing through a cross section per unit time.

The unit of charge is Coulomb (C) and the unit of time is second (s).
Since current is the ratio of charge and time, the unit of current is coulomb per second ($C{{s}^{- 1}}$).
1 coulomb per second is said to be equal to 1 ampere (A).
i.e. $1A=1C{{s}^{-1}}$.

If there is a current of 1 A flowing through a cross section, then its means that a charge of 1 Coulomb is flowing through that cross section in one second.

We know that electrons possess some charge. Therefore, we can associate the flow of charge with flow of electrons.

The charge on an electron is $1.6\times {{10}^{-19}}C$.

Now, let us find how many electrons are equivalent to a charge of 1C.

For this divide 1C by $1.6\times {{10}^{-19}}C$.
$\Rightarrow \dfrac{1C}{1.6\times {{10}^{-19}}C}=6.25\times {{10}^{18}}$.

This means that $6.25\times {{10}^{18}}$ electrons make up 1C of charge.

Therefore, when we say that there is current of 1A, it is equivalent to a flow of $6.25\times {{10}^{18}}$ electrons per second.

Hence, the correct option is A.

Note: As said above current is equal to the amount of charge flowing per unit time. This means that a constant current (i) is equal to the total charge flown (q) through a point (or cross section) in a given time (t) divided by the given time.
i.e. $i=\dfrac{q}{t}$.