Conductors and Insulators

Introduction 

When you touch the metal handle of a pan under normal conditions, you will find it cold. However, as soon as you start cooking something in it, the pan’s handle will become hot along with the base of the utensil. This is because the pan is made up of metal that can conduct the heat energy due to molecular movement from one point to another. Almost all non-living substances are divided into conductors and insulators of heat energy. For example, aluminium, steel, iron, and others are considered good heat conductors. On the other hand, wood, glass, rubber, and so on are insulators of heat energy.

What are conductors of heat energy?

Thermal conductors can transfer heat energy from one point to another using molecular vibrations. For example, let us consider a metal rod. Since atoms present in the metal are held together using a strong electrostatic force of attraction, they constantly vibrate to and fro from their mean positions. As a result, they can conduct the heat energy easily from one point of the rod to the other.

What are insulators of heat energy?

On the other hand, any object or material that cannot transfer heat between two points is considered an insulator. They are made from loosely bonded atoms and molecules, so energy conduction between one point and another is not possible. For example, consider the glass pane of your window. In the summer season, the outside of the glass surface will feel hot because of the incident sun rays. However, the inner surface will be at room temperature because both glass and the air trapped between are bad conductors of heat energy.

How to identify a thermal conductor and insulator? 

To check whether any given object is a thermal conductor or insulator, it is essential to consider whether it can work with conductivity. Thermal conductivity is mainly defined by its ability to transfer heat energy from one place to another without any movement of atoms and molecules. 

According to another physical definition, thermal conductivity is an attribute that defines the amount of heat conducted per unit time and area through any metallic plate with unit thickness, provided the two points have unit temperature differences. 

So, based on this latest definition, we can form the formula of thermal conductivity. 

k= QL/A(T1-T2)

Here, k is defined as the thermal conductivity coefficient. Q is the amount of energy transferred, L is the material’s length, A represents the surface area. In contrast, T1-T2 will define the temperature difference between two points. 

For denoting this attribute of both conductors and insulators, one needs to use its SI unit or W/mK or Watt per degree of temperature in Kelvin scale per metre. 

The thermal conductivity value will vary from one material to another based on their composition, thickness, and even surface area. For example, to know whether aluminium is a conductor or insulator, you must consider its thermal conductivity value. 

Thanks to their high coefficient, metals like aluminium, gold, and copper can easily conduct heat energy. On the other hand, the coefficient is pretty low if you consider air or wood. Therefore, they are insulators.

How is heat energy conducted?

The conductors and insulators are made from atoms with the least atomic space and a high level of electrostatic force of attraction. However, in the conductors, the atoms vibrate from their mean position at high speed, making them ideal for energy conduction. 

Let us take an example to understand this concept in a better manner. Ten people are standing in a single queue and looking in the same direction. The first person standing receives a book and is instructed to pass the object to the last person without moving from the position. 

Therefore, to fulfil this criterion, the first person faces the person standing next to him, hands over the book, and returns to the original position. The second person also follows the same method and so on. 

This activity will be continued till the book reaches the last person. However, if the people are tied to their chairs or placed far apart from each other, they will not pass the book without moving from one place to another. 

This example is the easiest way to answer the difference between a conductor and an insulator. When the atoms are placed together, like in the first scenario, they will contact each other due to vibrations from their mean position. 

Once it touches another atom, a portion of heat energy will be transferred to the next atom. By following such a method, heat energy is conducted from one product to another.

Conductor VS insulator- a brief study

It can be not easy to understand the difference between a conductor and an insulator. For this reason, a parallel study has been drawn here to understand whether common materials like aluminium are conductors or insulators. 

A few examples of heat conduction 

Before wrapping up, let us give two examples each of conductors and insulators of heat to become clear. 

1. Utensils made from cast iron, stainless steel, and aluminium are good conductors of heat. These elements have tightly packed atoms that vibrate rapidly and conduct energy. 
2. Plastic utensils are bad conductors of thermal energy. Therefore, they will not harm your fingers after keeping hot food items in them. 
3. Another example of conductors and insulators is copper and wood. If you consider wood only, it will not be able to transfer the heat. However, once you wrap a copper sheet around it, you can feel the thermal energy spreading slowly across the entire length. 

Conclusion

Several thermal conductors and insulators have applications in daily life. From making utensils to covering heating appliances with non-conducting materials, these objects are used to ensure that one can carry out the activities smoothly. The amount of heat to be conducted is also indirectly related to the specific heat capacity of a substance. Therefore, it is difficult to judge the objects based on their thermal conductivity. Moreover, this value will vary from one object to the other, which is why steel can conduct heat faster than thick iron.