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30 Cards in this Set
- Front
- Back
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What does infrared radiation involve? |
Transfer of heat energy by electromagnetic radiation
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What is infrared radiation also known as? |
Thermal radiation
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What do all objects emit and absorb?
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Infrared radiation
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What does the amount of infrared radiation given off depend on?
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Surface, Shape and Dimensions
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When will an object emit and absorb infrared radiation faster?
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If there is a bigger difference in temperature between it and its surroundings
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What are the characteristics of a dark, matt surface in terms of infrared radiation?
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They emit and absorb more infrared radiation than light, shiny surfaces
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What are the characteristics of a light, shiny surface in terms of infrared radiation?
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Poor emitter/absorber. Good reflector. |
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How do particles in a gas behave?
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quick motion, colliding with particles and walls of container
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What happens when the temperature of a gas decreases?
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move more slowly. Get closer. Collisions less frequent.
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How can solid particles move?
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They vibrate in a fixed and orderly position
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How can liquid particles move?
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move around each other at random. stay close together
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What are the properties of a liquid?
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They flow and take the shape of the container–Particles can move around each other. Cannot be compressed– No gaps between particles because they are so close together.
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What are the properties of a gas?
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They flow and completely fill the container– Particles can move quickly in all directions. They can be compressed– Particles are far apart and have space to move.
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What is conduction?
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The transfer of energy by heating
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How does conduction work in a metal?
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The free electrons transfer heat energy to the cooler parts of the metal because they can collide with the ions as they move
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What is convection?
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The transfer of energy by heating through the movement of particles
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What states of matter does convection occur in?
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Liquids and gases
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What is evaporation?
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Transfer of energy at the surface of a liquid. When a liquid becomes a gas.
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How does evaporation work?
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–Particles that are moving most rapidly are located at the surface, they behave like a gas and escape. –This causes the energy of the liquid to reduce which results in a fall in temperature
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What is condensation?
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When a gas becomes a liquid
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How does condensation work?
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When a gas looses energy and cools, the particles become closer together and bonds form between them which releases energy
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When does the rate of condensation increase?
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When the temperature of the gas decreases
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When does the rate of evaporation increase?
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When the temperature of the liquid increases
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What 2 factors affect the rate of evaporation and condensation?
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The surface area of the liquid. If air is moving over the surface of the liquid.
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What 4 factors affect the rate at which materials transfer energy?
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Surface area and volume of the material. Type of material. Nature of surface with which the material is in contact with. Temperature of the material.
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What is a U–value?
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The measurement of the amount of energy lost from a building
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If the U–value is low, what does this indicate?
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The material is a good insulator
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What is specific heat capacity?
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The amount of energy required to change the temperature of 1kg of material by 1'C
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What does the efficiency of a device refer to?
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The proportion of energy that is usefully transferred
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What does the amount of energy transferred by an electrical appliance depend on? |
"How long the appliance is switched on for and how fast the appliance transfers energy" |
