How does the temperature of an object affect the rate at which it emits infrared radiation?
The higher the temperature the greater the rate of emitting infrared radiation.
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Why can infrared radiation get to us from the Sun?
Infrared radiation can travel through vacuums, in this case, space.
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Why are houses in hot countries usually painted white?
Light surfaces are poor absorbers of infrared radiation. This means that the house will heat up slower.
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Why are pipes on the back of a fridge usually painted black?
Dark, matt surfaces are the best emitters of heat, so they cool down quicker, keeping the contents of the fridge cool.
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Which surfaces are the best at reflecting infrared radiation?
Light, shiny surfaces.
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What are the difference between the particles in a solid than to a liquid?
Particles in a solid are in a fixed arrangement and vibrate whereas particles in a liquid are in contact with each other but can slide around and flow. Solids are also the most dense.
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What are the difference between the particles in a liquid than to a gas?
Particles in a gas are usually far apart and move at random much faster. Particles in a liquid are also stay in contact and slide and flow with each other. Gases are also the least dense.
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Why are saucepans often made of metal with wooden handles?
Metals are good conductors so will cook food whereas wood is a poor conductor so you won't burn your hand.
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Why are materials that trap air poor conductors/good insulators?
Air is a gas, and gases are poor conductors.
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Why can convection only occur in fluids?
Particles in solids are in a fixed position so can't flow and become less dense.
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Why do fluids become less dense when heated?
The fluid expands, so there is the same mass in a larger volume.
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What factors increase the rate of evaporation?
A higher surface area of the liquid, more contact with the air and higher temperatures.
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What factors affect the rate of condensation?
Larger surface area, smaller surface temperature.
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What is the equation for specific heat capacity?
E = m x c x θ where E is the Energy Transferred (J), m is mass (kg), c is the specific heat capacity (J/kg°C) and θ is the temperature change (°C)
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The specific heat capacity of oil is 2100J/°C. How much energy is needed to raise the temperature of 1kg of oil by 1°C?
You need 2100J. E = mcθ and 1 x 2100 x 1 = 2100.
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8400J is used to raise the temperature of water (specific heat capacity of 4200J/°C) by 1°C. What was the mass of the water?
The water weighs 2kg. m = E / (c x θ) and 8400 / (4200 x 1) = 2
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What does the U-value of a material tell us?
It tells us how much energy passes through it each second.
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Give 6 ways to insulate a building.
Fibreglass loft insulation, foil between radiator and wall, solar heating panels, double-glazed windows, draught excluders, cavity wall insulation
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What is payback time?
The amount of time it takes for the money saved from insulation to pay for the cost of the insulator.
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Other cards in this set
Card 2
Front
How does the temperature of an object affect the rate at which it emits infrared radiation?
Back
The higher the temperature the greater the rate of emitting infrared radiation.
Card 3
Front
Why can infrared radiation get to us from the Sun?
Back
Card 4
Front
Why are houses in hot countries usually painted white?
Back
Card 5
Front
Why are pipes on the back of a fridge usually painted black?
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