Electricity – Definition, Electric Cell, Electric Switch

Key Concepts

1. Electricity
2. Electric cell and battery
3. Lighting element in a torch
4. Switch

Electricity

Introduction

We see various objects in our daily lives which run on electricity such as lamps, lights, air conditioner, microwave, etc. These are called electrical appliances, as they run on electricity. These appliances make our lives easier. 

Introduction

Electricity: 

Electricity is a form of energy that is used to operate electrical devices such as lights, television, room heater, air conditioners, etc. Electricity makes it possible to light not only our homes but also the roads, the streets, the factories, the marketplaces, etc. Electricity is generated in power stations and then transmitted to our homes, factories, offices, schools, etc.  

However, when there is a power cut, we usually use a torch to see things around us. The torch has a bulb that turns on when it is switched on. We can use the torches during a power cut as they do not use the electricity from the supply, but they have their power supply within them, called the cells. 

Electric cells: 

When we look inside the body of a torch, we see one or more cylindrical structures. These are called electric cells. The electricity to the bulb of the torch is supplied by these electric cells. Electric cells are used in alarm clocks, wristwatches, cameras, etc. 

An electric cell produces electricity from the chemicals stored within it. When these chemicals are used up fully, the electric cell cannot produce electricity. In such a case, it needs to be replaced. 

An electric cell has a small metal cap on one side and a metal disc on the other. These are marked as ‘+’ and ‘-’, respectively, which refer to the positive and negative terminals. All electric cells have two terminals, namely, positive and negative terminals. 

A torch often has more than one cell which supplies electricity to it. Such a collection of more than one cell (used as a power supply) is called a battery. In a battery, the positive terminal of a cell is connected to the negative terminal of another cell. 

Lighting element in a torch: 

The filament is held by two thick wires on both sides. One of these two wires is connected to the metal case at the base of the bulb, and the other is connected to the metal tip at the center at the bottom of the base. The metal tip and the base of the bulb are the two terminals of the bulb. The two terminals of the bulb are fixed in such a way that they do not touch each other. Both the bulb and the cell have two terminals each. One should be careful not to join the two terminals of a cell directly using a wire, as it would drain out the cell. 

Electric switch: 

A torch has a slide switch that is moved or pressed to turn a torch on and off. In fact, a switch is a device that is used to turn any electric appliance on and off.   

Question and answer: 

Which of the following is/are not electrical devices? 

1. Light bulb  

2. Window  

3. Oil lamp 

4. Microwave oven  

5. Gas burner  

6. Washing machine 

Answer: 

Electrical devices: Light bulb, microwave oven, washing machine. 

Not electrical devices: Window, oil lamp, gas burner. 

Summary:

1. Electricity is a form of energy that is used to operate electrical devices such as lights,
   television, room heater, air conditioners etc.
2. Electricity is generated in power stations and then transmitted to our homes, factories,
   offices, schools etc.
3. In a torch, the electricity is supplied by electric cells. They produce electricity by the
   chemicals stored in them.
4. A cell has two terminals viz positive and negative terminals.
5. A set of more than one electric cells connected together is called a battery.
6. A torch either has an electric bulb which has a thin wire called the filament enclosed in a
   glass covering or an LED that light up when switched on.
7. A bulb has two terminals viz the metal tip and the base of the bulb.
8. One should be careful not to join the two terminals of a cell directly using a wire, as it
   would drain out the cell.
9. A torch is a device which is used to turn an electric appliance on and off.