Conduction Convection and Radiation

Heat is transferred from a higher-temperature body to a lower-temperature body. Heat can be transferred from one body to another using any of the following modes: conduction, convection, or radiation. The following simple article will help you understand these three forms of heat transfer from one place to another.

Heat transfer

When a system with a higher temperature comes into contact with a system with a lower temperature, energy is transferred from the first system’s particles to the second system’s particles. As a result, heat transfer can be described as the process of transferring heat from a higher-temperature item (or system) to a lower-temperature object (or system).

Convection

The process of heat transmission between a solid and a liquid or fluid in contact with the solid is known as convection. Convection is required when transferring heat from one liquid to another through a barrier. Thermal diffusion (fluid molecule mobility) or advection (heat transfer by bulk motion of heat currents in the fluid) are the two methods of convectional heat transfer.

When a fluid is heated from below, it expands thermally. As the fluid becomes hotter, its density falls in the lower levels. Because of buoyancy, the hotter, less dense section of the fluid rises and is replaced by denser, cooler fluid. When this section heats up, it rises and is replaced by the higher, colder layer, repeating the process. Convection is utilised to transfer heat in this way.

Examples:

• As we approach the equator, warm water flows towards the poles, while colder water flows towards the equator
• Warm-blooded creatures circulate their blood by convection, which helps to control their body temperature
• One of the most common examples of natural convection is the phenomenon of sea and land wind

Conduction

Conduction is one of the three basic mechanisms for transferring heat energy from one place to another. The other two types of heat transport are radiation and convection. In the process of conduction, heat energy is conveyed through collisions between nearby atoms or molecules. Solids and liquids, which have closer particles, conduct better than gases, which have greater space between them. The rate of energy transfer by conduction is faster when the temperature difference between the substances in contact is large.

Examples:

• A heating pad can be used to warm your back muscles. As the pad heats up, it distributes heat to the portion of your body it comes into contact with
• The heat from a hot drink heats up the cup as well. If you pick up a cup of hot coffee, tea, or broth, we can only feel the heat when we hold the cup
• If you’re cold and someone holds you to keep you warm, the heat is transferred from their body to yours
• If you leave a metal spoon propped up in a saucepan, the boiling water within the pot will heat it up

Radiation

In some form, radiant heat is present in our daily lives. Thermal radiations are referred to as radiant heat. The production of heat radiation is caused by the emission of electromagnetic waves. These waves carry the energy from the generating body away. Radiation can occur in a vacuum or through a clear solid or liquid substance. Thermal radiation is caused by the random movement of molecules in materials. The movement of charged electrons and protons causes electromagnetic radiation to be emitted.

Examples:

• Radiation in the form of heat and light is emitted by a burning candle
• Light, heat, and particles are all forms of radiation emitted by the Sun
• The decay of Uranium-238 into Thorium-234 produces alpha particles, which emit radiation
• Photons are emitted when electrons move from one energy state to a lower energy one

Difference between conduction convection and radiation

1. Heat is transferred between things through direct contact through conduction. The heat transmission takes place within the fluid via convection. Heat is transferred through electromagnetic waves without the use of particles in radiation.
2. The heat transmission is caused by the temperature difference in conduction. The heat transmission is caused by the density difference in convection. All things with a temperature greater than 0 K experience heat transfer through radiation.
3. Conduction is a sluggish method of heat transmission. Convection allows for faster heat transmission. Radiation is the quickest way to transmit heat.
4. Conduction and convection do not follow the law of refraction and reflection whereas radiation follows the law of reflection and refraction.

Conclusion

The transmission of energy through molecular motion is what heat conduction is all about. Energy is transferred from a high to a low temperature zone when one part of the body is warmer than the other. High temperatures are linked to greater molecular energies, which means that when two molecules collide, energy must be transferred from the more energetic to the less energetic.