Electricity — Electric Circuit and Circuit Diagram ( Part 2 )
In previous part , we learned that Cell or Battery is used as Source of Electricity which helps to maintain Potential Difference to get continuous flow of Electric Current.
To glow Light Bulb , We need at least 4 things — Light Bulb , Cell or Battery, Switch and Conductor Wire. These are called Electric Components.
Electric Circuit is Proper Arrangement of these Electric Components to get continuous Flow of Electric Current.
A continuous conducting path consisting of wires and other resistances (like electric bulb, etc.) and a switch, between the two terminals of a cell or a battery along which an electric current flows, is called a Electric Circuit.
OPEN Circuit / Switch OFF
When Switch is OFF , we say , Electric Circuit is OPEN.
Electric Current do not flow through wire.
In OPEN Circuit Diagram , Arrows on the Line are NOT shown because Electricity do not flow through Wire.
CLOSED Circuit / Switch ON
When Switch is ON , we say , Electric Circuit is CLOSED.
We get Continuous flow of Electric Current through wire.
In CLOSED Circuit Diagram , Arrows on the Line are shown because Electricity flows at this Moment.
It is difficult to draw sketch of Electric Circuit.
Electric Symbols / Circuit Symbols
So, Scientists designed List of Symbols representing various Electric Components like Light Bulb , Switch , Battery etc. These symbols called Electric Symbols or Circuit Symbols.
A diagram which indicates how different components in a circuit have been connected by using the Electric symbols for the components, is called a Circuit Diagram.
A Electric Cell is a device which converts Chemical energy into Electricity — used as Source of Electricity
In Electric Symbol for Cell , The longer vertical line represents the positive terminal of the cell (so it is marked plus, +), whereas the shorter vertical line represents the negative terminal of the cell (so it is marked minus, –)
A Battery is a device made up of Two or more Cells — connected in series.
In order to obtain a battery, the negative terminal of the first cell is joined with the positive terminal of the second cell, and so on.
Connecting Wire is made up Copper Wire with Insulated Coating over it which is used to connect all Electric Components in the Electric Circuit.
Its main purpose is continuous Flow of Electric Current — acts as a Conductor of Electricity.
Resistance ( Resistor )
Fixed Resistance ( Resistor ) are used to reduce Electric Current in Electric Circuit.
Variable Resistance ( Rheostat )
Rheostat is a variable resistance which is usually operated by a sliding contact on a long coil (made of resistance wire).
A rheostat is used to change the current in a circuit without changing the voltage source like the cell or battery. It can do so by changing the resistance of the circuit.
Ammeter is used to measure Electric Current in Electric Circuit.
Ammeter is always connected in Series with Resistor because it has low resistance.
This is because current to be measured in the circuit should not be practically affected by the Ammeter.
Voltmeter is used to measure Potential Difference ( Voltage )
Voltmeter is always connected in Parallel with Resistor because it has High Resistance.
Voltmeter has been connected across the ends of the Resistor
Galvanometer is used to detect Electric Current in Electric Circuit
Electric Switch is used to allow or break the flow of Electric Current in Electric Circuit.
Electric Bulb is used to produce Light.
In Next part , We will learn about Ohm’s Law.