Energy Transfer By Heating.

  • Created by: cieran_10
  • Created on: 16-01-18 00:00
What are thermal conductors? (2.)
They are materials that allow thermal energy to move through then easily.
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What are all metals, in terms of conductivity?
They are all good thermal conductors.
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What are thermal insulators? (2.)
They are materials that do not allow thermal energy to move through them easily.
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Why are fibreglass and wool good thermal insulators?
As they trap air.
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Give the three things that decides the rate of energy transfer through a material.
The temperature difference across the material, the density of the material and the thermal conductivity of the material.
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Give the two things that reduce the rate of energy transfer for a material.
They will have the lowest thermal conductivity as possible for the material and it must be as dense as possible.
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What spectrum are infrared radiation/waves in?
The electromagnetic spectrum.
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How is the wavelength (of infrared waves) different to the wavelength of normal visible light?
The wavelength is longer.
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How can you detect infrared radiation? (2.)
With our skin; it makes you feel warm.
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What d all objects emit?
Infrared radiation.
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Complete the sentence: the hotter the object the __________ it emits?
The more infrared radiation.
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At what rate is infrared radiation emitted at, when it is at a constant tempperature?
It is at the same rate that it is absorbed at.
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Is the Perfect Black Body the best possible emitter of infrared radiation?
Yes, it is.
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What is the name given to radiation emitted by a perfect black body?
Black body radiation.
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What happens to the wavelengths, of the infrared radiation waves, when an object is at a constant temperature?
They emit radiation across a continuous range of wavelengths.
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Complete the sentence: the intensity of the radiation emitted by an object has a peak at _________?
A certain wavelength.
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What does the peak radiation, that an objet emits, depend on?
It depends on the temperature of an object.
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What causes infrared radiation to to absorb and emit and the same rate?
A constant temperature.
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What happens to the temperature of an object that absorbs infrared radiation at a greater rate than it emits it?
The temperature of the object decreases.
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What happens to the temperature of an object that absorbs infrared radiation at a lesser rate than it emits it?
The temperature of the object decreases.
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What type of surface emits radiation at a good rate?
Dark and matt surfaces.
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What type of surface emits radiation at a not so good rate?
Light and shiny surfaces.
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What s the source of infrared radiation?
The sun.
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Give the three things that happens to infrared radiation when it reaches earth.
Some is reflected back into space, some is absorbed by the earth's atmosphere and the rest is absorbed by the earth's surface.
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What two things does the temperature on earth depend on?
The rate at which radiation from the sun is reflected or absorbed by the earth's surface and atmosphere. Secondly, it depends on the rate a which radiation is emitted from the earth's surface and from the earth's atmosphere back into space.
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What molecules, in the air, absorb and re-emit the radiation back into the ground?
Carbon dioxide molecules.
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What happens when you heat a substance?
You are transferring thermal energy to the object, being heated.
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What is specific heat capacity? (2.)
The amount of energy needed to increase the temperature of 1kg of substance by 1 degrees celsius only.
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When there is a high specific heat capacity, would you need to supply more or less thermal energy to increase an objects temperature by 1 degrees celsius?
More energy.
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Does a greater object mass require more or less energy to increase its temperature by 1 degrees celsius?
More energy.
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Why do people try to minimise the rate of energy transfer from their home?
In order to reduce their fuel/heating bills.
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What does fibreglass loft insulation do? (2.)
It reduces the rate if energy transfer through the roof.
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What does cavity wall insulation do? (2.)
Reduces the rate of energy transfer through the outer walls.
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What does aluminium foil behind radiators do? (2.)
It reflects infrared radiation back into the room.
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What does double glazing do? (2.)
It reduces the rate of energy transfer through the windows.
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What do thick bricks with low thermal conductivity do? (2.)
They reduce the rate of energy transfer through the exterior walls.
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What do solar heating panels do?
They heat water directly, using infrared radiation from the sun.
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Other cards in this set

Card 2

Front

What are all metals, in terms of conductivity?

Back

They are all good thermal conductors.

Card 3

Front

What are thermal insulators? (2.)

Back

Preview of the front of card 3

Card 4

Front

Why are fibreglass and wool good thermal insulators?

Back

Preview of the front of card 4

Card 5

Front

Give the three things that decides the rate of energy transfer through a material.

Back

Preview of the front of card 5
View more cards

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