What is Conduction? – Definition, Types With Examples

Conduction Overview

Have you ever wondered why the pan gets hot on the flame? Or when you side the pan from the flame, it gets cool. Why? Why do your clothes get dried when you iron them? Why do you feel hot in the winter near the heater? Why do you feel hot in summer, even inside the house? Can you think of a concept behind all these questions?

What is happening in all the questions as mentioned above is conduction. Now, the question is, what is conduction? What is the definition or meaning? Or what are examples?

What is Conduction?

When you put a pan on the flame, it gets hot. It is because the heat passes from flame to pan. And it lets the pan or any other utensil get hot. But when you remove the vessel from the flame, it cools down after some time. This is because the heat of the vessel gets transferred into the surroundings. It lets the vessel cool down.

In both cases, the heat is transferred from the hot object to the cold object. It generally happens in all cases. The process by which heat is transferred from the hot end of one object to its cold end is called conduction.

In solids, heat is generally transferred by the process of conduction. In the case of liquids and gases, this process happens because of convection. 

Definition of Conduction

It is the operation of heat transport between two adjoining parts of a body due to their temperature differences. In this process, the actual movement of the body is not involved. However, the movement of molecules decides the flow of heat. In simple words, The definition is the flow of heat through and within the body.

Usually, the word means transferring energy from one place to another. Still, here every particle of the medium remains in its original state.

Types of Conduction

Every object is made up of atoms or molecules. In physics, the process of conduction mainly occurs in two forms:

1. Heat (Thermal or Conduction by heat)

• Steady-state conduction
• Non-steady state (or Transient conduction)

2. Electrical (Conduction by electricity)

In these two ways, you can describe the behavior of the heat transfer process. These are defined below:

1. Heat Conduction:

It refers to a transfer of heat, especially thermal energy. As the temperature of the object increases, the molecule inside the object starts to vibrate. This movement of molecules generates heat energy, which passes through the object to its surroundings.

Touching a burning light bulb, melting chocolate in your hands, holding someone’s hands when you feel cold in winter, etc., are situations of thermal conduction. The transfer of energy in different objects depends on the object’s material, the object’s size, and the object’s temperature gradient. The temperature gradient is the direction and temperature change rate from one point to another.

Thermal conduction can be further classified into two classes:

• Steady-State Conduction:

Suppose the body’s heat transmission is not affected by time interval. In that case, such a heat conduction definition is for steady-state conduction. In the case of steady-state, the energy entered into the body is always equal to the energy exiting the body.

Generally, The heat received by the body is partly converted into heat radiation. At the same time, another part is conducted to the next section of the object.

For example, when one part of the iron rod is heated, there is a continuous change in temperature at different points of the rod. After some time, a state is reached when the temperature at all the parts of the object gets steady. This state is called a steady state.

• Non-Steady State Conduction:

This type of conduction is also known as Transient Conduction. In this mode of conduction, the temperature can vary at any part of an object at a given time. The basic principle of this is the time dependence of the temperature on the body.

This means of conduction generally occurs when an alteration in temperature is introduced within the outer or inside areas of the body. This sudden temperature change happens when a new heat source is entered within the object.

For example, the starting of an engine in a vehicle. In this case, a new heat source is added when the engine is turned on. However, this conduction phase is only for a hasty moment. When the engine reaches a certain manageable temperature, the steady-state phase appears.

2. Electrical Conduction:

The transfer of heat in an object when electricity is passed through it is called electrical or conduction by electricity. This means to pass electrically charged particles with the help of a transmission medium from one end of a body to another.

When electrically charged particles, electrons, or ions are moved, they carry electricity. That movement results in the mode of electrical conduction. When you switch on an electrical appliance, it starts to work. It happens because of electrical conduction. Metals are generally known as good conductors of electricity.

In the case of metals, they have loosely packed atoms at the end of the object. That helps them move freely. That is why they are good conductors of electricity. In the case of liquids, they do not have any free electrons. Therefore, to break their bonds, certain compounds are added to them. After which, they can show the property.

Examples of Conduction

You may have experienced that when an ice-cold water glass is a left-in open in the days of summer, it eventually warms up. The reason behind this is, of course, conduction. Whenever there is a difference in the temperature of a body and its surroundings, there is a heat transfer between them. This process continues until the temperature between the body and the surrounding medium becomes equal.

1. A cup of hot tea cools down when you place it on the table and leave it intact.
2. Placing a hot water bottle on the body when feeling cold. Your body will start to feel hot.
3. If you stir the soup using a spoon or ladle of steel, leave it in the utensil on the flame for some time. It gets hot.
4. When hot water spills on your body, you get burned or scalded.
5. The water gets heated when putting a hot iron rod in the water bucket.
6. On a cold, windy day, you can feel warm when you enter your house.
7. It is difficult to hold a hot metallic rod with bare hands.
8. During the daytime, the sun heats the land, and at night times, the land cools down.
9. Patients having heartbeat problems are treated by installing pacemakers to stimulate conduction.
10. In the presence of water, you get electrocuted when you touch the electric wire.
11. Electric appliances you use are working because of the electrical conductors.

You come across many more conduction examples daily in your daily life.

Conductors and Insulators

The handles of kitchen utensils are generally made of different materials than the utensils. It helps protect you from getting burnt. Hence, these materials are called the poor conductors of heat. Insulators are objects that do not allow heat to pass through them. And the objects that allow passing heat through them are known as conductors.

Some materials that are good conductors of heat and electricity are metals like iron, aluminum, copper, gold, silver, mercury, bronze, steel, etc., and non-metals like graphite. Some insulator materials are air, oil, pure water, rubber, plastic, diamond, glass, dry paper, etc.

Summary

From the above discussion, you will be well-versed in what conduction is and its meaning. In Physics and Chemistry, heat and temperature terms are related to conduction. The dictionary conduction meaning is ‘the process by which heat or electricity passes through a material.’ It can be thermal or electrical. The transfer of heat is thermal conduction, while the transfer of electrons is electrical conduction.

The substances that pass heat or electricity through them are good conductors. In contrast, those that do not allow them to pass are termed bad conductors (or insulators).

Frequently Asked Questions

Q1. What is the Principle Behind Conduction?

Answer: In the process of conduction, the molecules or atoms of the body near the hot ends absorb the energy. As a result, the amplitude of vibration about their signified position increases. Due to this increment, they strike with their nearest atoms, molecules, or particles. And hence, transferring some part of the energy, they absorb to others. This process continued till the other end molecules.

Q2. What is the Convection of Heat?

Answer: Convection is a mode of transferring heat. Unlike conduction, this process involves the movement of matter. Therefore, convection is possible only in liquids or fluids. It involves the flow of matter within the fluids due to unequal temperatures of its parts. The melting of ice is an example of conduction.

Q3. What Does the Radiation of Heat Refer to?

Answer: The mechanism of transfer of heat where no medium is required is called radiation. In this mode of heat transmission, energy travels through matter or space in the form of electromagnetic waves and, therefore, is known as radiant energy. All bodies, whether they are solid, liquid, or gas, emit radiant energy. Getting an X-ray or chemotherapy in the hospital is performed by the radiation process.