Energy Transfer by Heat
Black is a good absorber/emitter of infrared radiation faster transfer of
energy
Matt surfaces are better emitters of infrared radiation than shiny surfaces
Black is a good emitter of infrared radiation and will give maximum
energy transfer
Increasing the surface area increases the rate of energy transfer
Reducing convection = air bubbles trapped in foam means the air cannot
form convection currents
Conduction through metals = a metal has free electrons and when it is
heated up the kinetic energy of the electrons increases. This means the
electrons move faster and transfer energy to other electrons by colliding
with each other. Also, when there is a temperature gradient, thermal
energy moves to the colder area by conduction. The electrons in the metal
diffuse through the metal and collide with other electrons to transfer the
kinetic energy and thus the thermal energy
Convection = water molecules gain energy which make the particles move
apart. This causes the water to become less dense and the warm water
rises
Convection = cold air loses energy which makes it more dense. This
makes cooler air fall and warm air at the bottom rises.
When water changes from a gas to liquid, kinetic energy of the particles is
reduced and the particles move closer together
U value = how effective a material is as an insulator
Double-glazing provides better insulation as it has a lower U-value. This
means there is less energy transfer through double glazing
Solids have particles close together so no room for particles to move
closer (so hard to compress). The particles are strongly held together in a
fixed shape by strong forces of attraction. They also vibrate about fixed
apart.
Gases have larger volumes than solids because there is a strong force of
attraction between particles holding the particles close together in solids
while in a gas the forces between particles are negligible so the particles
spread out. The particles also move far apart and randomly meaning
there are spaces between particles.
Why does a liquid cool down as it evaporates = there are attractive forces
between molecules. Only the fastest molecules have enough energy to
break away from other molecules. These molecules escape from the
surface of the liquid therefore the average speed / energy of the
remaining molecules goes down. The lower the average speed / energy of
molecules the lower the temperature of the liquid
When surface is warm, condensation is reduced
Black is a good absorber/emitter of infrared radiation faster transfer of
energy
Matt surfaces are better emitters of infrared radiation than shiny surfaces
Black is a good emitter of infrared radiation and will give maximum
energy transfer
Increasing the surface area increases the rate of energy transfer
Reducing convection = air bubbles trapped in foam means the air cannot
form convection currents
Conduction through metals = a metal has free electrons and when it is
heated up the kinetic energy of the electrons increases. This means the
electrons move faster and transfer energy to other electrons by colliding
with each other. Also, when there is a temperature gradient, thermal
energy moves to the colder area by conduction. The electrons in the metal
diffuse through the metal and collide with other electrons to transfer the
kinetic energy and thus the thermal energy
Convection = water molecules gain energy which make the particles move
apart. This causes the water to become less dense and the warm water
rises
Convection = cold air loses energy which makes it more dense. This
makes cooler air fall and warm air at the bottom rises.
When water changes from a gas to liquid, kinetic energy of the particles is
reduced and the particles move closer together
U value = how effective a material is as an insulator
Double-glazing provides better insulation as it has a lower U-value. This
means there is less energy transfer through double glazing
Solids have particles close together so no room for particles to move
closer (so hard to compress). The particles are strongly held together in a
fixed shape by strong forces of attraction. They also vibrate about fixed
apart.
Gases have larger volumes than solids because there is a strong force of
attraction between particles holding the particles close together in solids
while in a gas the forces between particles are negligible so the particles
spread out. The particles also move far apart and randomly meaning
there are spaces between particles.
Why does a liquid cool down as it evaporates = there are attractive forces
between molecules. Only the fastest molecules have enough energy to
break away from other molecules. These molecules escape from the
surface of the liquid therefore the average speed / energy of the
remaining molecules goes down. The lower the average speed / energy of
molecules the lower the temperature of the liquid
When surface is warm, condensation is reduced
