ELECTRIC CURRENT IN A CIRCUIT
ELECTRIC CURRENT IN A CIRCUIT
Introduction
Electricity plays a very important role in our daily life. Devices like bulbs, fans, televisions, computers, and mobile phones work due to electric current. To understand electricity, we must first understand electric current and how it flows in a circuit.
What is Electric Current?
Electric current is defined as the rate of flow of electric charge through a conductor.
In simple words, when electric charges move from one place to another in a material, electric current is produced.
In metal wires, electric current is due to the movement of electrons.
In liquids and gases, electric current is due to the movement of ions.
Electric current is denoted by the symbol I.
Flow of Electric Charges
Electric charges do not flow on their own. They require:
A source of electrical energy
A conducting path
A closed circuit
When these conditions are satisfied, charges start moving, and electric current flows.
Electric Circuit
An electric circuit is a closed conducting path through which electric current flows.
Components of an Electric Circuit
Electric Cell or Battery
Provides electrical energy
Creates potential difference
Connecting Wires
Made of conducting materials like copper
Allow charges to move
Switch (Key)
Used to open or close the circuit
Controls the flow of current
Electric Device
Bulb, resistor, motor, etc.
Uses electrical energy
Open Circuit and Closed Circuit
Closed CircuitWhen the switch is ON, the circuit is complete, and current flows.
Open Circuit When the switch is OFF, the circuit is broken, and current does not flow.
A bulb glows only when the circuit is closed.
Electric Current Direction
Conventionally, electric current is considered to flow from positive terminal to negative terminal of the cell.
In reality, electrons flow from negative terminal to positive terminal.
This difference is due to historical reasons.
MEASURING ELECTRIC CURRENT
Unit of Electric Current
The SI unit of electric current is ampere (A).
One ampere is defined as the flow of one coulomb of charge per second.
Smaller units:
Milliampere (mA)
Microampere (µA)
Instrument Used to Measure Current
Electric current is measured using an instrument called an ammeter.
Ammeter
An ammeter is a device used to measure the amount of current flowing in a circuit.
Properties of an Ammeter
It has very low resistance
It allows maximum current to pass through it
It gives accurate current readings
CURRENT IN A SERIES CIRCUIT
What is a Series Circuit?
A series circuit is a circuit in which all components are connected one after another, forming a single path for current flow.
IMPORTANT KEY WORDS
Electric Current
Electric Circuit
Cell
Battery
Switch
Ammeter
Ampere
Series Circuit
Resistance