Question

S.I unit of electric current is
A. Ampere
B. Volt
C. Farad
D. Coulomb

Answer 1

Hint: In this question, we will first see the definition of ampere that is it is the total amount current due to 1 Coulomb of charge passing through a circuit for 1 second that is $1ampere = \dfrac{{1Columb}}{{1\sec }}$.

Step-By-Step answer:
The S.I unit of current is Ampere. Ampere is denoted by the letter A in the International System of Units. This term is given after the name of a French physicist/mathematician, André-Marie Ampèrein.
We all know that

$Current = \dfrac{{Ch\arg e}}{{time}} = \dfrac{{Columb}}{{\sec }}$

So the SI unit for electric current is Coulomb per Second that is known as Ampere.
We can define 1 ampere as it is the total amount of current that is produced When 1 coulomb of charge is passed through a wire of uniform cross-sectional area for 1 second time as shown in figure 1.

Figure 1


$1ampere = \dfrac{{1Columb}}{{1\sec }}$

There is one more very famous definition of 1 ampere that is When two current-carrying parallel infinitely long wires are placed such that the distance between them is one meter and the direction of current and amount of current in both the wires is the same then They will exert force on each other because each wire will have its own magnetic field. When this value of force between them becomes $2 \times {10^{ - 7}}$ newton/m 1 ampere of the current will be passing through each one of the two. This can be seen in figure 1.

Figure 1


Note: For these types of questions we need to know the definition of some basic units for different electricity-related terms such as ampere (A), volts (V), Ohms $\left( \Omega \right)$, Siemens (S), Columb (C). It will be helpful for us to know the expression force due to the current-carrying conductor and what is the nature of the force.