Chapter 10: Transfer of Thermal Energy

Medium

A space, an object. Something that allows energy to pass through.

Convection

-For fluids(liquid or gas) Convection is the transfer of thermal energy by means of convection currents in a fluid, due to a difference in density

Conduction

-For solid particles Conduction is the transfer of thermal energy through a medium without any flow of the medium

Why do metals conduct thermal energy more quickly?

-Metals contain FREE ELECTRONS -In non-metals, thermal energy is transferred through the vibration and collision of particles. -In metals, thermal energy is transferred through the vibration and collision of particles AND the process of free electron diffusion -In metals, electrons gain kinetic energy and move more rapidly. They collide with atoms in the cooler parts of the metal and pass on their energy in the process

How its transferred

-Thermal energy is transferred from a region of HIGHER temperature to a region of LOWER temperature -Through the process of conduction, convection and radiation

Factors affecting the rate of emission and absorption of infrared radiation

1. Colour and texture of the surface ->Dull and black surfaces are better emitters and absorbers of infrared radiation than shiny and silver surfaces 2. Surface temperature ->The higher the temperature of an object's surface relative to the surrounding temperature, the higher the rate of emission of infrared radiation 3. Surface area ->Larger surface area will emit or absorb infrared radiation at a higher rate

Conduction VS Convection

Conduction: Thermal energy is transferred fro. One particle to another Convection: Thermal energy is transferred through the actual movement of the heated particles from the warmer to cooler parts of the fluid.

Why does convection only occur in fluids but not solids?

Convection involves the bulk movement of the fluid that carried the thermal energy. For solids, thermal energy is transferred from one particle to another through vibrations, without any bulk movements of the particles(conduction).

Metal->Much better conductor than glass

Particles move much mor vigorously, particles collide to each other ->Molecules move faster when heated

Radiation

Radiation is the transfer of thermal energy in the form of electromagnet waves such as infrared radiation without the aid of a medium.

Conduction in everyday life

The design of cooking utensils and table mats

Radiation in daily life

The design of greenhouses

Convection in daily life

The design of hot water systems and electric kettles

Conduction, Convection and Radiation in daily life

The design of vacuum flasks

Convection current

movement of fluid caused by a difference in densities of various parts of the fluid