Definition of Electric current
- Electric current is often termed as ‘current’ and it is represented by the symbol ‘I.
- It is defined as the rate of flow of charges in a conductor.
- This means that the electric current represents the number of charges flowing in any cross-section of a conductor (say a metal wire) in unit time.
- If a net charge ‘Q’ passes through any cross-section of a conductor in time ‘t, then the current flowing through the conductor is
I = Q/t
SI unit of electric current
- The SI unit of the electric current is ampere (A).
- The current flowing through a conductor is said to be one ampere, when a charge of one coulomb flows across any cross-section of a conductor, in one second. Hence,
1 ampere = 1 coulomb / 1 second
- An electric circuit is a closed conducting loop (or) path, which has a network of electrical components through which electrons are able to flow. T
- his path is made using electrical wires so as to connect an electric appliance to a source of electric charges (battery).
- A schematic diagram of an electric circuit comprising of a battery, an electric bulb, and a switch is given
- In this circuit, if the switch is ‘on, the bulb glows. If it is switched off, the bulb does not glow. Therefore, the circuit must be closed in order that the current passes through it.
- The potential difference required for the flow of charges is provided by the battery.
- The electrons flow from the negative terminal to the positive terminal of the battery.
- By convention, the direction of current is taken as the direction of flow of positive charge (or) opposite to the direction of flow of electrons.
- Thus, electric current passes in the circuit from the positive terminal to the negative terminal.