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Physics > Energy > Flashcards

Energy Flashcards

1
Q

What does efficiency mean

A

Efficiency is a measure of how good a device is at changing energy from one form to another

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2
Q

What does power mean

A

Power is the amount of energy transferred by a device in one second

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3
Q

Conservation of energy

A

Energy in = energy out

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4
Q

What is an independent variable

A

The thing you change

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5
Q

Dependent variable

A

The variable you measure or test

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6
Q

Control variable

A

Variable you keep the same

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7
Q

What is a closed system

A

A system where it’s components only interact with itself not the outside world. No energy is exchanged outside the system.

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8
Q

What is an open system

A

A system where it’s components and energy are exchanged with the things outside the system

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9
Q

What are the ways heat can travel

A

Conduction
Convection
Radiation

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10
Q

What is conduction

A

The measure of heat transfer in solids but not liquids and gases

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11
Q

How does conduction work

A

Energy is passed along the particles of the solid. The particles gain more energy, vibrate more vigorously and collide with neighbours. The free electrons gain kinetic energy when a metal is heated.

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12
Q

What does insulate mean

A

To block from electricity or heat and reduce the amount of energy transfer across a material

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13
Q

What is specific heat capacity

A

The amount of energy needed to change the temperature of 1kg of the substance by 1•c

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14
Q

The amount of energy to heat a substance up depends on

A
  • mass of substance
  • the substance itself
  • the temperate change
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15
Q

What does the rate of energy transfer across a material depend on?

A

the temperature difference across a material
the thickness of the material
The thermal conductivity of the material

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16
Q

What is ideal properties of thermal insulation?

A

Have as low thermal conductivity as possible
Be as thick as practically possible

17
Q

What is payback time?

A

How long it takes for the cost of installing insulation to be equalled by the savings from reduced energy costs

18
Q

What is heat

A

The amount of of thermal energy stored in an object or substance

19
Q

Amount of heat out =

A

Amount of heat in - it’s thermal equilibrium where it matches it’s surroundings

20
Q

What is infrared radiation?

A

A type of electromagnetic wave which transfers heat energy

21
Q

What is emitted from objects as infrared radiation?

A

Thermal heat energy

22
Q

Matte black is …

A

The best emitter of infrared radiation and the best absorber

23
Q

Silver shiny is …

A

The worst emitter and absorber of infrared radiation but the best reflectors

24
Q

What is a black body emitter?

A

An object that absorbs all radiation that hits it and does not reflect any

25
Q

What is the greenhouse effect ?

A

Some gases in the atmosphere absorb larger wavelengths of infrared therefore stopping it leaving the earth and then it is emitted back into the earths surface making it warmer

26
Q

What does non renewable mean ?

A

limited supply

27
Q

What does renewable mean?

A

Unlimited supply

28
Q

How do fossil fuel power stations work?

A
  • chemical energy in coal is burnt and the heat generated is used to turn water into steam
  • the chemical energy decreases and is converted to thermal energy
  • the thermal store in the steam is converted to a kinetic store
  • it is used to turn the turbine and the steam’s kinetic energy passes to the turbine to spin
  • the turbine is connected to the generator making it spin as well as connecting the kinetic energy to electrical energy
29
Q

What is biofuel?

A

Fuel taken from recently living organisms

30
Q

Positives of biofuel

A

Renewable source
Carbon neutral

31
Q

Renewable energy sources

A

Solar , hydroelectric , biofuel, wind, tidal, wave power, geothermal

32
Q

Non renewable energy

A

Coal, nuclear , oil , natural gas

33
Q

How does nuclear power work?

A

Nuclear fuel uses the energy from unstable atoms when they split. This is called nuclear fission. The energy from the nuclear material in the core releases heat energy which is transferred to a fluid which is pumped through the core

Physics (19 decks)

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