HeatHeat

ByNeil Bronks

ByNeil Bronks

ExpansionExpansion Atoms vibrate more at higher

temperature Atoms vibrate more at higher

temperature

Zero Kelvin

(-2730C)

200 Kelvin

(-730C)

400 Kelvin

(1270C)

ExpansionExpansion This makes objects take up more

volume This makes objects take up more

volume

Zero Kelvin

200 Kelvin

400 Kelvin

Ball and ringBall and ring

Proves solids expand when heated

SolidsSolids Expansion can damage railway

lines Expansion can damage railway

lines

Expansion Joints on Bridges

Expansion Joints on Bridges

Bi-Metallic StripBi-Metallic Strip

The bottom metal expands more than the top strip.

It bends! Used to control

Gas Oven

The bottom metal expands more than the top strip.

It bends! Used to control

Gas Oven

Bi-Metallic StripBi-Metallic Strip

The bottom metal expands more than the top strip.

It bends! Used to control Gas Oven

The bottom metal expands more than the top strip.

It bends! Used to control Gas Oven

LiquidsLiquids Use to measure temperature as

liquid expands up a tube Use to measure temperature as

liquid expands up a tube

Gas Gas Expands a lot with a small

temperature rise Expands a lot with a small

temperature rise

Heat TransferHeat Transfer

Conduction-Transfer

byvibrations

Radiation-Transfer by

Electro-magnetic wave

Convection- Hot air

risingcarrying

theheat up with it.

ConductionConductionIn a solid every atom is physically bonded to its neighbours in some way.If heat energy is supplied to one part of a solid, the vibration travels through the solid.

Conduction is the transfer of energy through matter from particle to particle. It is the transfer and distribution of heat energy from atom to atom within a substance.

Internet ConductionInternet Conduction

Practical ConductionPractical Conduction

A spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids

It is also why stone and metals appear cold. They are just good conductors.

A spoon in a cup of hot soup becomes warmer because the heat from the soup is conducted along the spoon. Conduction is most effective in solids

It is also why stone and metals appear cold. They are just good conductors.

Chilly

Water as a Poor Conductor

Water as a Poor Conductor

HEAT

The ice does not melt as the water is a terrible conductor and convection only works up.

Metal Gauze

ICE

Test Tube of water

ConvectionConvection

Most houses have radiators to heat their rooms. This is a bad name for them - as they give off heat mainly by convection!

Most houses have radiators to heat their rooms. This is a bad name for them - as they give off heat mainly by convection!

The air expands and is less dense so it rises

It then cools and falls

CONVECTION CURRENT

Internet exInternet ex

Example of convection currentSea Breezes

Example of convection currentSea Breezes

HOT LAND WARM SEA

Day – On Shore

Sea Breeze NightSea Breeze Night

COLD LAND WARM SEA

Night – Off Shore

Ventilation with convection

Ventilation with convection

Mine Ventilation DemoMine Ventilation Demo

RadiationRadiation

The transfer of heat in the form of an electro-magnetic wave.

Only form of heat that can travel through a vacuum

The transfer of heat in the form of an electro-magnetic wave.

Only form of heat that can travel through a vacuum

A silver or white body are good at holding and reflecting heat.

Black bodies are good at radiating and absorbing heat.

InsulationInsulation

Vacuum stops heat loss by conduction and convection

Silver prevents heat loss by radiation

Vacuum stops heat loss by conduction and convection

Silver prevents heat loss by radiation

Latent HeatLatent Heat

When something boils it takes in heat to change state

Its temperature does not rise.

Latent heat just changes state

When something boils it takes in heat to change state

Its temperature does not rise.

Latent heat just changes state

Heating a solidHeating a solid

Temperature

Time

Melting point

Boiling point

Heating a solidHeating a solidTemperature

Time

Boiling point

Melting point

Melting

Solid

Boiling

Liquid

GasHeat raises

temperature

Latent Heat Only

SweatSweat Our sweat evaporates and takes

heat from our bodies Liquid sweat takes heat from skin as

it turns to vapour

Our sweat evaporates and takes heat from our bodies

Liquid sweat takes heat from skin as it turns to vapour

Uses of Latent HeatUses of Latent Heat

Perspiration-Liquid evaporates to gas takes heat from our skin

Boiling or Melting matter Refrigeration-liquid boils to take

heat from food Heat Pumps- reverse of refrigerator Latent heat is heat that changes

state

Perspiration-Liquid evaporates to gas takes heat from our skin

Boiling or Melting matter Refrigeration-liquid boils to take

heat from food Heat Pumps- reverse of refrigerator Latent heat is heat that changes

state

The FridgeThe Fridge

The RefrigeratorThe Refrigerator

Compressor

Liquid GasLiquid boils and takes in Latent Heat from the food

Gas turns back into a liquid giving out heat

SummarySummary

Conduction Convection Radiation

Particles vibrate and transfer their heat to the next particle

Particles move and bring their heat with them

Heat transferred without the need of a medium (waves)

SummarySummary Water a poor conductor Black good emitter and absorber Silver and white a good reflector and

insulator Latent Heat is the heat lost or gained

as a material changes state – e.g. sweat

Expansion is the volume change in solids liquids and gases.

Water a poor conductor Black good emitter and absorber Silver and white a good reflector and

insulator Latent Heat is the heat lost or gained

as a material changes state – e.g. sweat

Expansion is the volume change in solids liquids and gases.

H/WH/W

P336 1,2,5,7,8,9,10,11,12,13 P336 1,2,5,7,8,9,10,11,12,13