#### notes

**ELECTRIC CURRENT AND CIRCUIT:-**

-The flow of electric charge is known as electric current. Electric current is carried by moving electrons through a conductor.

-**Electric circuit**: A continuous and closed path of an electric current is called an electric circuit.

-**Expression**: Electric current is expressed by the amount of charge flowing through a particular area in unit time or it is the rate of flow of electric charges.

-If a net charge Q, flows across any cross-section of a conductor in time t, then the current I, through the cross-section is I=Q/t

-**Direction of current**:-

Electrons flow from the negative terminal to the positive.

Conventional current flows from the positive terminal to the negative.

-It is important to realize that the difference between conventional current flow and electron flow in no way effects any real-world behaviour or computational results.

**SI Unit of electric charge**:-

-The SI unit of electric charge is Coulomb (C), which is equivalent to the charge contained in nearly 6 × 1018 electrons.

**Ampere:-**

- The electric current is expressed by a unit called ampere (A).

- One ampere is constituted by the flow of one coulomb of charge per second, that is, 1 A = 1 C/1 s

-Small quantities of current are expressed in milliampere (1 mA = 10–3 A) or in microampere (1 µA = 10–6 A)

**Ammeter:-**

-An instrument called ammeter measures electric current in a circuit. It is always connected in series in a circuit through which the current is to be measured.