Physics 1 Revision Lesson 1 Kinetic theory and Heat transfers

Kinetic theory

In solids the particles are packed very close together In solids the particles are packed very close together. They vibrate about fixed positions In liquids the particles are close together but not as close as they are in solids. They can move around in any direction and are not fixed in position. In gases the particles are very far apart with large distances between them. They move around very quickly in all directions

Increasing the amount of energy = more vibrations and more space Decreasing the amount of energy = less vibrations and less space

Conduction, Convection and Infrared radiation

Conduction is the movement of heat through a metal solid Conduction is the movement of heat through a metal solid. Good conductors of both heat & electricity are usually metals due to their free electrons

Convection is the movement of heat through a fluid (liquid or gas) Convection is the movement of heat through a fluid (liquid or gas). The hot liquid rises as it is less dense

All hot objects emit infrared radiation the hotter the object, the more infrared radiation given off infrared does not require particles and can travel through a vacuum Dark & Matt surfaces = good absorbers and emitters Light & Shiny surfaces = poor absorbers & emitters BUT good reflectors

Key words and statements

Kinetic theory and Heat transfers Solid the particles are very far apart with large distances between them. They move around very quickly in all directions liquid How heat travels through a solid. Metals are usually good conductors of heat gas How heat travels through a liquid. As a liquid increases in temperature, the hot liquid rises due it lighter density conduction the particles are packed very close together. They vibrate about fixed positions convection the particles are close together but not as close as they are in solids. They can move around in any direction and are not fixed in position. Infrared radiation A material which does not have a sea of free electrons and therefore doesn’t allow heat to pass through easily Insulator Electromagnetic radiation that we can feel as heat. Conductor A material which has a sea of free electrons and allows heat to pass through easily

Kinetic theory and Heat transfers Solid the particles are very far apart with large distances between them. They move around very quickly in all directions liquid How heat travels through a solid. Metals are usually good conductors of heat gas How heat travels through a liquid. As a liquid increases in temperature, the hot liquid rises due it lighter density conduction the particles are packed very close together. They vibrate about fixed positions convection the particles are close together but not as close as they are in solids. They can move around in any direction and are not fixed in position. Infrared radiation A material which does not have a sea of free electrons and therefore doesn’t allow heat to pass through easily Insulator Electromagnetic radiation that we can feel as heat. Conductor A material which has a sea of free electrons and allows heat to pass through easily

Kinetic theory and Heat transfers A change of state occurs when… The hot liquid being less dense and therefore lighter. This causes a convection current Decreasing the amount of energy a particle has… Dark and matt surfaces All good conductors are… Infrared radiation, as it does not need particles and can travel through a vacuum like space when hot liquid rises and cold liquid sinks, it is due to … Atoms or particles gain enough energy to turn into another state Good absorbers and emitters of infrared radiation are… Usually metals and have a ‘sea of free electrons’ Good reflectors of infrared radiation are… Conduction, convection and infrared radiation Thermal energy is transferred by … Causes it to vibrate less We receive our sun’s rays via… Light and shiny surfaces

Kinetic theory and Heat transfers A change of state occurs when… The hot liquid being less dense and therefore lighter. This causes a convection current Decreasing the amount of energy a particle has… Dark and matt surfaces All good conductors are… Infrared radiation, as it does not need particles and can travel through a vacuum like space when hot liquid rises and cold liquid sinks, it is due to … Atoms or particles gain enough energy to turn into another state Good absorbers and emitters of infrared radiation are… Usually metals and have a ‘sea of free electrons’ Good reflectors of infrared radiation are… Conduction, convection and infrared radiation Thermal energy is transferred by … Causes it to vibrate less We receive our sun’s rays via… Light and shiny surfaces