Energy Transfered By Heating Flashcards
Energy can be transferred by heating in 3 ways:
Radiation, conduction or convection
Thermal radiation is the transfer of energy by heating through __________
Infrared (electromagnetic) waves
Conduction and convection are energy transfers that involve the transfer of energy by __________
Particles
Conduction is the main form of energy transfer in ________
Solids
Convection is the main form of energy transfer by heating in _________ and _____
Liquids and gasses
Emission of __________ occurs in _______, __________ and _____. Any object can both absorb and emit _______________, weather or not conduction or convection is taking place.
Emission of Thermal radiation occurs in Solids, liquids and gasses Any object can both absorb and emit Thermal radiation, weather or not conduction or convection is taking place.
The _______ temperature difference, the faster energy is transferred between thermal energy stores of an object and its surroundings.
Bigger*
What can thermal radiation also be called?
Infrared (IR) radiation
All objects are ________ emitting and absorbing Infrared radiation
Continually*
An object that’s hotter than it’s surroundings admits More/Less radiation than it absorbs (as it cools down)
More (not less)
An object that’s colder than it’s surroundings absorbs More/less radiation than it emits (as it warms up)
More*
Can you feel infrared radiation?
Yes (eg: standing near a fire)
Do some colours and surfaces absorb and emit radiation better than others?
Yes
In a sold particles are held ______ together. So when one particle vibrates, it collided a with other particles near by and the vibrations pass quickly from particle to particle.
Tightly/ Close
Thermal conduction is:
The process where vibrating particles transfer energy from their kinetic energy store to the kinetic energy store of the neighbouring particles
This process ______ throughout the solid and gradually passed all the way through the solid, causing a rise in __________ at the other side of the solid. It’s then usually transferred to the thermal energy stores of the surroundings or anything touching the object
Continues* Temperature*
Name the main form of energy transfer by heating in a solid
Conduction
When does convection occur?
When the more energetic particles move from the hotter region to the cooler region
Convection simply _______ happen in solids because the particles _______ move apart (they can only vibrate)
Cannot* Can’t *
In what shape containers is convection most efficient?
Round/square
Why do hot fluids rise in a convection current?
Because heated fluids expand, becoming less dense
Convection occurs mainly in ________
A) fluids
B) solids
C) Gasses
A) fluids
Heat = more energy in the particles kinetic energy store
More heat = ?
They move quicker
Where do heated/ energetic particles move to?
The cooler area
The high energy particles in a hotter region are more _________
Spread out**
What happens to a fluid in a warmer region?
It expands and becomes less dense
What’s a convection current?
Are a flowing fluid or gas that is moving because there is a temperature or density difference within the material
How do you reduce convection?
Stop the free flow of air/fluids
Eg: sleep under a blanket
What does conduction and convection have in common?
They both involve particles gaining kinetic energy
To reduce energy transfers away from a system by conduction use materials with a low/high thermal conductivity
Low*
Insulation such as clothes, blankets and foam cavity wall insulation, all work by trapping pockets of air. The air can’t move so the energy has to conduct very slowly/fast.
Slowly*
A black surface is better/worse at absorbing and emitting IR radiation than a white one
Better*
A matte (dull) surface is worse/better at absorbing and emitting radiation than a shiny one
Better*
Why would hot water in a black mug cool down faster than if the mug was white?
Because a black surface absorbs and emits infrared radiation better than white surface.
