Physics 1A revison cards

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What type of radiation transfers heat energy?
Infrared radiation
1 of 30
What is infrared radiation?
All objects emit (give out) and absorb (take in) thermal radiation, which is also called infrared radiation. The hotter an object is, the more infrared radiation it emits.
2 of 30
Can radiation travel through a vacuum?
Yes
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Factors that affect rate at which heat radiation is given out
Dark, Matt surfaces emit more than white shiny surfaces
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Factors which affect the rate of radiation being taken in
Dark, Matt surfaces absorb infrared radiation better than light shiny surfaces
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How is heat transferred from the sun to the earth?
Radiation
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Name the process that heat in transferred through a solid
Conduction
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Describe how heat in transferred through a solid
As something is heated the particles vibrate and pass on there kinetic energy to neighbouring particles.
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Name process that heat is transferred through a liquid
Convection
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Describe how heat is transferred through a liqiud
Particles get more energy as they get heated so move around faster. This means more distance between them making the liquid less dense, this makes the hotter(less dense) water to rise above the colder more dense water.
10 of 30
What effect would water evaporation from your skin have on you?
It would cool you down
11 of 30
List factors that affect rate of heat transfer
The surface Area, Type of material (good/bad conductor) etc..
12 of 30
What is a heat sink?
A device designed to transfer heat away from objects such as computers. They have fins with a large surface area so they emit heat away asap.
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How does the glass bottle(double glazed by a vacuum) and silvery surface of a vacuum flask help reduce heat loss?
The glass bottle is doubled walled with a vacuum which stops all conduction and convection through the sides. The walls either sides of the vacuum are silver to keep heat loss by radiation to a minimum as silvered surface reflect heat back in.
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How does the insulating foam and plastic stopper of a vacuum flask help reduce heat loss?
Insulated foam is a good insulator to keeps the heat in and also minimizes heat conduction in or out from glass bottle. The plastic stopper reduces heat conduction through it.
15 of 30
Which animals transfers heat at greatest rate?
An desert fox as as they have huge ears with a large surface area which allow them to lose heat through radiation.
16 of 30
List all the way you can reduce heat loss energy at home
Loft insulation, Cavity wall insulation, Hot water tank jacket, Double glazing, Draught- proofing.
17 of 30
Explain the difference between "most effective" and "most cost effective"
Most effective are the ones that give you the biggest annual salving, The most cost effective method tends to be the cheapest one.
18 of 30
Equation for payback time
payback time = initial cost/annual saving
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What would payback time be if initial cost was £500 and the annual saving was £70
Payback time = 500/70 = 7.14 = 7 years
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What does a "U" value show?
Rate of heat transfers through materials, Higher "U" value = faster heat transfer.
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What is the formula for specific heat capacity?
E = MASS X SPECIFIC HEAT CAPACITY X TEMPERATURE CHANGE
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How much energy is needed to heat 2 kg of water from 10-100 degrees
2 x 4200 x 90 = 756000J
23 of 30
Explain why a high specific heat capacity is necessary for heaters
So that they can store high amounts of energy
24 of 30
Explain why some heaters use oil which has a lower specific heat capacity than water
Oil has a higher boiling point which means they can safely reach higher temperatures than water ones
25 of 30
Give all nine forms of energy
Electrical energy, Light energy, Sound energy, Kinetic energy, Nuclear energy, Thermal energy, Gravitational Potential energy, Elastic potential energy, Chemical energy.
26 of 30
State the law of conservation of energy
Energy cannot be created or destroyed but can only be passed from one object to another or change from one form to another. EG Solar panels get light energy then turn it into heat energy.
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In what form is energy usually lost
Heat
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What is the formula for calculating efficiency?
Efficiency = useful energy out/total energy in
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What the formula for calculating the % efficiency?
Efficiency = Useful power out/ Total power in
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Other cards in this set

Card 2

Front

What is infrared radiation?

Back

All objects emit (give out) and absorb (take in) thermal radiation, which is also called infrared radiation. The hotter an object is, the more infrared radiation it emits.

Card 3

Front

Can radiation travel through a vacuum?

Back

Preview of the front of card 3

Card 4

Front

Factors that affect rate at which heat radiation is given out

Back

Preview of the front of card 4

Card 5

Front

Factors which affect the rate of radiation being taken in

Back

Preview of the front of card 5
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