Heat Transfer Notes
9.2 Heat Transfer
Energy
Energy is defined as the ability to exert a force and cause change, such as moving or deforming an object.
Types of Energy
There are different types of energy.
Law of Conservation of Energy
Energy cannot be created or destroyed.
Energy can be transformed or converted into other forms of energy.
Heat and Temperature
The amount of heat energy (or thermal energy) that an object has is due to the total kinetic energy of every particle in the object.
Kinetic energy: energy due to the motion of an object
The temperature of any substance is linked to the average kinetic energy of the particles of that substance.
Heat Flow
When an object is warmer than its surroundings, heat energy will flow out of it in one or more ways.
These ways are conduction, convection, and radiation.
Conduction
Conduction occurs when a particle passes kinetic energy on to another particle. This can happen during collisions.
The particles in a solid have bonds between them. These help to transfer the energy from the hot region to the cold region.
The particles at the warm end gain kinetic energy.
This means they vibrate more.
As the faster particles are connected to other particles by bonds, the neighboring particles are pulled around more.
This means that energy has been transferred.
Preventing Heat Transfer Through Conduction
Insulators: materials that have a very high resistance, allowing very little current to flow through them.
Heat sink: a device that transfers the heat generated by an electronic or a mechanical component to a coolant, often the air or a liquid, where it can be taken away from the component.
Convection
Unlike the particles that make up solids, those of liquids and gases are able to move around.
In liquids and gases, heat can be transferred from one region to another by the actual movement of particles.
Radiation
Heat can be transferred without the presence of any particles at all, as electromagnetic radiation or light.
Heat transferred in this way is called radiant heat.