Electricity and Circuits

Introduction

Advantages of Electricity

• Light in our houses, offices, roads etc. even past sunset
• To operate pumps which in turn have a lot of applications
• Electrical appliances like refrigerator, fans etc.
• Building houses, installing equipment etc.

Current

• Current is the flow of particles in a particular direction. E.g air currents that cause winds or water currents.
• When particles flow in an electric circuit to produce electricity, it is called an electric current.

Electric current

• The flow of electric charges in a circuit is called an electric current. The direction is taken from the positive terminal to the negative terminal of the battery in an external circuit

Electric cell

Features of an Electric Cell:

• It is a small cylindrical structure which helps in operating the devices.
• A small metal cap is placed on one side and a metal disc is present on the other side.
• All cells have two terminals: Positive and Negative.
• The metal cap and metal disc are positive (+) and negative (-) terminals of the electric cell respectively.
• Chemical energy is converted into electrical energy inside a cell. When the chemicals are exhausted, the cell stops working.

We use electric cells to supply the energy needed for electrons to move around an electric circuit. A battery is a group of two or more electric cells that are connected. The electric cell system works to generate electricity.

Power station: Electricity that we use at homes, in our factories, is supplied from a power station.

A Bulb connected to an electric cell

A Bulb Connected to an Electric Cell

Filament: In an electric bulb, there is a thin tiny wire inside the glass cover. This is called a filament.

Terminal: All types of electric cells have two terminals:

• a positive terminal
• a negative terminal

Wire :

• An electric wire is a conducting path in an electric circuit, through which current flows.
• It is usually made out of a metal that is a good conductor of electricity.

Electric Bulb and its Working:

• It consists of a thin wire that glows due to the passage of current. This is known as the filament.

• An electric circuit provides a closed path for the current to flow. The terminals of the bulb are connected by wires to the electric cell.
• Sometimes the bulb does not glow as the filament gets fused (breaks) due to overheating.

An Electric circuit

An Electric Circuit

An electrical circuit is a simplified representation of an electric circuit element.

Consider an electric cell and a bulb. The terminals of the cell are connected to the terminals of the bulb by the means of electric wires. Such an arrangement of cell and bulb is called an Electric Circuit.

• The circuit is said to be complete in this case because of which electricity will flow and the bulb will glow.
• This uses standard symbols for the components in the circuit and does not show the physical arrangements of the components.
• At present, our daily life on the earth has become nearly impossible without electricity. Homes to big industries depend on electricity.
• Electric current flows in a closed circuit loop. It is a closed-loop in which continuous electric current goes from the supply to the load equipment.
• A closed-loop path, which the current takes is known as an electric circuit.
• When the path of the circuit is closed, current flows through it.
• When there is a break in the path (switch is open) then, the circuit is open and not conducting so the current does not flow.
• One should be careful while setting up an electric circuit. It should be done under supervision.

An Electric Switch

Electric Switch

• Switch is an integral part of an electric circuit. It is a simple device which breaks or completes a circuit.
• Electric switch is a simple device that either breaks the circuit or completes it to stop or start the flow of current
• When the switch is connected, we call it ON, and when it’s not in contact (or open) with the circuit, the switch is OFF

Electric Conductors and Insulators

Conductors - Materials that allow electricity to flow through them easily.

Insulators - Materials that do not allow electricity to pass through them.

• Human body is a conductor, so touch a current carrying wire is detrimental and so insulating it prevents from an electric shock.
• Some examples of conductors are: Metals like copper, Iron
• Some examples of insulators are: Rubber, Plastic

This sign is used in areas which are near electric junctions as a warning.

Electrical Safety

Electricity can be very dangerous if you do not handle electrical devices carefully. One should never play with electrical wires and sockets. Electricity from cells is safe and you can experiment with it, but you have to be careful not to connect the two terminals of a cell directly through a wire/conductor. Electricity generated by portable generators is dangerous and should not be used for experiments.

A demo video link to understand the working of Electric Circuit

https://youtu.be/GMS6SUYqsMM

Conclusion:

• Source of electric current: A device that can be used to produce an electric current is called a source of electric current.
• Electric circuit: A path for an electric current to flow is called an electric circuit.
• Closed-circuit: A circuit that has an ‘unbroken path’ through which an electric current can flow is called a closed circuit.
• Open circuit: A circuit with a break in it is called an open circuit.
• Electric switch: A device that is used to open or close a circuit is called an electric switch.
• Conductor (in this chapter): A material that allows electric current to pass through it easily is called a conductor.
• Insulator (in this chapter): A material that does not allow an electric current to pass through it easily is called an insulator.
• In a dry cell, a chemical reaction takes place to produce an electric current.
• A dry cell contains solid or semisolid ingredients.
• All cells have two terminals: the positive and the negative terminal.
• Electric current flows only if there is an unbroken or complete path, starting from one terminal of the source, through various devices back to the other terminal of the source.
• An electric switch is a device that is used to open or close a circuit.
• Safety is important while using electricity.