Heat is a form of energy that flows as a result of temperature difference between two points or region where it passes from a body at higher temperature to the body at lower temperature.
Heat can also be defined as the energy that flows from places of high temperature to places with low temperature.
A body that receives heat has it’s temperature being increased and a body that looses heat has it’s temperature lowered.
If two bodies are at different temperature in the same environment, heat flows from the body at high temperature to body at low temperature until the two bodies are at the same same temperature which is usually a temperature that is between the two initial temperatures. The two bodies are then said to be in thermal equilibrium.
The SI unit for heat is joule(J).
There is no instrument to measure heat directly but when we see a body rising in temperature, we know it has absorbed heat. However, we will expound more on how to measure heat in future lessons.
Heat flow is responsible for the presence of wind in our environment.
What is temperature?
Temperature is the quantity that measures degree of hotness or coldness of a place or an object.
When we talk about degree of hotness, we talks about the feeling. Not a very good way of describing a scientific phenomena. But a more technical definition of temperature is that temperature is the quantity that describes the average energy of particles in a material.
A large heat can cause very little rise in temperature of a substance but also small absorption of heat can cause large increase of temperature. So heat is usually described as the total amount of energy that flows from a body at high temperature to a body at lower temperature.
The temperature change caused by a given heat on a substance depends on the mass of the object and the internal molecular structure of the substance, which is usually known as the heat capacity of the substance.
Heat is measured in joules( the unit for energy) but temperature is measured in Kelvin.
Temperature is a basic physical quantity whereas heat is a derived quantity.
Modes of heat transfer
The common methods by which heat traves from one point to another includes:
- Conduction
- Convection
- Radiation
Conduction
Heat conduction is a process where molecules that are close to the source of heat picks up the heat, vibrates faster and passes on the excess heat to their immediate neighbouring molecules.
The neighboring molecules upon receiving energy from their neighbors increases their vibrations but with with a slower later than the molecules that gave the the energy since they got just a small part of the supplied energy. Therefore, temperature reduces along the material as one moves away from the source.
Convection
Convection is the transfer of heat by the actual movements of the molecules where molecules that receives heat becomes lighter and moves up to allow colder molecules to come to regions of heat.
Convection is the most important means by which heat is transferred in liquids and gases.
Convection can be described as the continuous flow of liquid and gas particles in a complete loop due to a difference in temperature.
Radiation
It is a method of heat transfer by means of electromagnetic radiation.
Electromagnetic radiation are waves that does not need material medium to transfer.
Electromagnetic waves moves the same way, heat from the sun reaches the earth service as it travels without aid of any medium.