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.
- 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)
-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.
Shaalaa.com | Electricity part 7 (Electric Current)
Find the odd one out:
(i) Voltmeter, ammeter, galvanometer, thermometer.
(ii) Loudspeaker, bar magnet, electric motor, microphone.
Fill in the blank:
To increase the effective resistance in a circuit the resistors are connected in _____________.
Draw the electrical symbols of the following components and state its use:
Rheostat (variable resistance)