Switch and Conductors – Definition and Explanation

Switch and Conductors

Key Concepts

1. Electric Switch
2. Conductors and Insulators

Introduction

We know that a bulb connected to a closed electric circuit glows. However, we do not want a bulb in our room to glow all the time. Sometimes we want it to remain off, for example, while we sleep. We can put the bulb off by disconnecting two pieces of wire in its electric circuit. However, this way of turning the bulb on and off is not practical and easy. We might even end up getting an electric shock in this process. Thus, there need to be some means by which we can turn the bulb on and off effortlessly. 

Explanation

Electric switch: 

A switch is an electrical component of an electric circuit that is used to turn the circuit on and off easily and effortlessly. A typical electric switch looks as shown in figure 3.1 below. 

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.

In fact, a simple switch can be made at home using commonly available objects. For this, we need two drawing pins, a piece of cardboard, two pieces of wire and a paper clip. In order to test the working of the switch, we need to make a simple circuit using a cell, a small bulb and a few connecting wires.  

The following steps can be taken to make a simple switch at home. 

• Fix the drawing pins on a piece of cardboard with a gap roughly equal to the length of the paper clip between them. 
• Then fix the paper clip to one of the drawing pins as shown in the picture so that it is free to rotate about the drawing pin. 

 

The setup in which the paper clip is not touching the other drawing pin is an open switch, as it breaks the circuit.  

The setup in which the paper clip is moved on to the other drawing pin is a closed switch, as it closes the circuit.  

Now let us connect the open switch and then the closed switch to an electric circuit. 

• When the paper clip is not in contact with the other drawing pin, the circuit does not provide a complete pathway to the electric current flowing in the circuit. 
• This creates a break in the circuit, and the bulb does not glow in such a case. 
• Hence the circuit is broken when the clip is in such a position. 

• When the paper clip is moved so that it encounters the other drawing pin, the circuit provides a complete pathway to the electric current flowing in the circuit. 
• This closes the circuit. 
• Hence, the circuit is closed when the clip is in such a position. 

The switches used to light electric bulbs, and other electrical appliances work on the same principle, although their design is somewhat complex.  

Conductors and Insulators: 

In the above section, we have used a metallic paper clip. The question is, can we use a plastic paper clip instead. We cannot use the plastic paper clip instead of the metallic one, as it does not let the electric current pass through itself. In fact, all the materials do not let the electric current pass through them. Various materials can be tested for their ability to allow electric current to pass through them.  

This can be done by making a tester by disconnecting the switch from the circuit already made. This gives rise to two pieces of wires with free ends. This tester can be used to test various objects by placing them in contact with those free ends and checking whether the bulb glows after placing them or not. If the bulb does not light up on connecting the free ends of the wire pieces to an object, it means that the object does not allow the electric current to pass through itself. If the bulb lights up on connecting the free ends of the wire pieces to an object, it means that the object allows the electric current to pass through itself. 

The materials which allow the electric current to pass through are called conductors. All the metallic objects such as the keys, copper utensils, aluminum articles, etc., are conductors. 

On the other hand, the materials which do not allow the electric current to pass through are called insulators. For example, thermocol, cardboard, plastic, rubber, etc., are insulators. 

Both conductors and insulators are equally important to us. Internally the wires and switches are made up of conductors such as copper, as they are required to conduct electricity. However, they are externally covered with plastic to keep their users from getting electric shocks. 

Question and answer: 

Identify the following objects as conductors or insulators. 

1. Thermocol 

2. Human body 

3. Air 

4. A log of wood 

5. A spoon 

Answer: 

The objects such as thermocol, air and a log of wood are insulators as they are not metallic. 

A human body is a conductor as a person gets an electric shock when they touch an uninsulated part of an electric circuit. As spoon is made up of metals therefore, it is a conductor.

Summary

1. A switch is an electrical component of an electric circuit which is used to turn the
   circuit on an off easily.
2. The materials which allow electric current to pass through are called conductors.
3. All the metallic objects such as the keys, copper utensils, aluminum articles etc. are
   conductors.
4. On the other hand, the materials which do not allow electric current to pass through are
   called insulators.
5. Examples of insulators are thermocol, cardboard, plastic, rubber etc. are insulators.
6. The electrical components are internally made of metals as it is required for them to
   conduct. However, they are covered externally using insulators to keep us from electrical shocks.