Question

Let q(t) be the electric charge in an element with respect to time, what is current through that element?

1. ∫ q(t)dt
2. q(t) × t
3. \(\frac{{dq}}{{dt}}\)
4. q(t) - t

Answer 1

Correct Answer - Option 3 : \(\frac{{dq}}{{dt}}\)

Electric current is expressed by the amount of charge flowing through a particular area in unit time. In other words, it is the rate of flow of electric charges.

Mathematically, this is defined as:

\(i = \frac{{dq}}{{dt}}\)

Notes:

• In circuits using metallic wires, electrons constitute the flow of charges.
• The electric current was considered to be the flow of positive charges and the direction of flow of positive charges was taken to be the direction of electric current.
• Conventionally, in an electric circuit, the direction of the electric current is taken as opposite to the direction of the flow of electrons.
• When a charge is transferred from one point in the circuit to another point, it constitutes what is known as electric current.