Question

When 1 coulomb of charge flows through any cross section of a conductor in 1 second, the electric current through it is said to be 1 ampere.
\[\begin{align}
  & A.True \\
 & B.False \\
\end{align}\]

Answer 1

Hint: We can justify the given statement easily by taking the definition of electric current. Ampere is the S.I. unit of current, so to get 1 Ampere we must take the parameters affecting electric current to unity. The area vector is not related to current but it is related to current density.
Formula used: \[I=\dfrac{Q}{t}\]

Complete solution:
Before solving the question, we must clearly understand what electric current is and how it is defined.
We can define electric current as, When there is transfer of charge from one side of an area to the other, we say that there is an electric current through the area. If the moving charges are positive, the current is in the direction of motion of the charges and if the charges are negative, the current direction will be opposite to the direction of motion of the charges.
That is, if a charge\[\Delta Q\]crosses an area in time\[\Delta t\], we can define the electric current through the area during this time as,

            \[I=\dfrac{\Delta Q}{\Delta t}\]

Thus, electric current through an area is the rate of transfer of charge from one side of the area to the other. The S.I unit of current is Ampere.
Now, let us take,
\[\begin{align}
  & Q=1coulomb \\
 & t=1\sec \\
\end{align}\]
Then, current will be, \[I=\dfrac{1C}{1s}=1A\].
That means, If 1 coulomb of charge crosses an area in 1 second, the current is 1 Ampere.

So, the given statement is TRUE. That means option a is correct.

Note: We must understand that electric current doesn’t depend upon the area of the cross section. So if we take whatever cross section the current will only be calculated on rate of transfer of charge. But when we deal with current density, it is related to the direction of the area vector.