# Revision for Physics 1a

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Name the three ways that heat can be transferred
1. Conduction 2. Convection 3. Radiation
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How does the temperature of the object affect the amount of radiation it emits and absorbs?
If an object is hotter than it's surroundings, it will emit more radiation than it absorbs
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Explain why a solar panel has a black matt surface
This is because black, matt surfaces are the best absorbers of infrared radiation
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Describe the arrangement and movement of particles in solids
The particles are held close together in a fixed, regular arrangement, and only vibrate about their fixed positions
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Describe the arrangement and movement of particles in liquids
The particles are held close together, but can move past each other and form irregular arrangements, and they move in random directions at low speeds
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Describe the arrangement and movement of particles in gases
The particles have almost no forces of attraction between them, and they are free to move and travel in random directions and at high speeds
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What is the name of the process where particles pass on their extra kinetic energy to neighbouring particles?
Conduction
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Which type of heat transfer can't take place in solids?
Convection
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Describe how the heat from a radiator is transferred throughout a room
The air around the radiator is heated, and the less dense air rises. The warm air displaces cooler air, which then causes it to cool and the denser air falls. Finally, cool air flows to fill the gap left by the rising heated air. The process repeats
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How do the densities of liquids and gases change as you heat them?
They become less dense
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What happens to the particles of a gas as it turns to a liquid?
The particles slow down and lose kinetic energy. The attractive forces between the particles pull them closer together, so the gas becomes a liquid
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What is the name of the process where a gas turns into a liquid?
Condensation
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Why does evaporation have a cooling effect on a liquid?
The particles with the most kinetic energy are most likely to evaporate from the liquid, so when they do the average speed and kinetic energy of the remaining particles decreases. This causes the temperature of the liquid to fall
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Name the four factors that cause the rate of condensation to be faster
1. Higher temperature 2. Lower density 3. Larger surface area 4. Greater airflow over the liquid
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Describe a feature of a vacuum flask that make it good at keeping liquids hot
The glass bottle is double-walled with a vacuum between the two walls. This stops all conduction and convection through the sides
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Explain why animals in hot climates have ears the size that they do
They have big ears with a large surface area to allow them to lose heat by radiation easily and keep cool
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What is pay-back time?
The time it takes for the money you've saved on heating bills to equal the initial cost of the insulation
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Name one type of improving energy efficiency in the home and explain why it is effective
Draught proofing: Strips of foam and plastic are put around doors and windows to reduce heat loss by convection
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What can you tell from a material's U-value?
The lower the U-value, the better the conductor (less heat transfer through the material)
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What property of a material tells you how much energy it can store?
Specific heat capacity
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Define specific heat capacity
It is the amount of energy needed to raise the temperature of 1 kg of a substance by 1 degree C
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Name the nine types of energy
Electrical, light, sound, kinetic, nuclear, thermal, gravitational potential, elastic potential and chemical
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What is the useful type of energy delivered in a motor?
Kinetic
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In what form is energy wasted in a light bulb?
Heat
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What are the standard units of electrical energy?
kWh
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## Other cards in this set

### Card 2

#### Front

How does the temperature of the object affect the amount of radiation it emits and absorbs?

#### Back

If an object is hotter than it's surroundings, it will emit more radiation than it absorbs

### Card 3

#### Front

Explain why a solar panel has a black matt surface

### Card 4

#### Front

Describe the arrangement and movement of particles in solids

### Card 5

#### Front

Describe the arrangement and movement of particles in liquids