2 - Energy Flashcards

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1
Q

What is efficiency?

A
  • A measure of how good a device is at changing energy from one store to another
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2
Q

How can efficiency be increased?

A

By reducing the amount of unwanted energy transfers that are produced

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3
Q

What is energy?

A
  • Often defined as ‘The capacity to do work’
  • Measured in Joules (J)
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4
Q

What are the main energy sources available for use on Earth?

A
  • Fossil Fuels
  • Nuclear Fuel
  • Bio-Fuel
  • Wind
  • Hydroelectricity
  • Tides
  • Sun
  • Geothermal
  • Water Waves
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5
Q

How are both renewable and non-renewable energy sources used?

A

Non:
- Power stations that use fossil fuels or nuclear fuel are very reliable sources of energy
- They operate almost continuously
- When additional power is needed, gas power stations are usually used because they will start up very quickly
Renewable:
- Water power eg tidal and hydroelectricity are reliable and predictable
- These two types can also be used to supply additional demand
- Many of the renewable sources are unreliable, including wind and solar energy

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6
Q

What are the patterns and trends in the use of energy resources?

A
  • Demand for energy varies with the time of year and the time of day
  • During evenings a lot of energy is needed for heating, lighting and cooking
  • Very little needed overnight
  • During winter there is more heating and lighting used than in summer
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7
Q

What is meant by the conservation of energy?

A
  • Energy can be transferred usefully, stored or dissipated, but it cannot be created or destroyed
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8
Q

What is an energy source?

A
  • An energy source is something we can release energy from , eg a fuel
  • Used in power stations to generate electricity
  • Energy source itself is a primary source
  • Electricity produced is a secondary source
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9
Q

What are some ways of reducing unwanted energy transfers?

A

Friction:
- Adding bearings to prevent components directly rubbing together
- Lubricating parts
Heat:
- Using lower resistance parts/lowering the current; reduces amount of heat produced
- Thermal insulation

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10
Q

What are the energy stores? Where are they stored (~)?

A
  • Gravitational Potential Energy (GPE) ~ Mass due to position
  • Kinetic Energy (KE) ~ Moving objects
  • Thermal Energy ~ Mass due to temp
  • Chemical Energy ~ In chemicals
  • Elastic Potential ~ Compressed/stretched items
  • Electrostatic ~ When elec charges interact
  • Magnetic ~ When two magnetic objects interact
  • Nuclear ~ Atomic Nuclei
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11
Q

How is energy transferred from one store to another?

A

Radiation - Electromagnetic waves & sound
Electrically - Electrical current
Mechanically - Force pushing/pulling
Heating - Temp difference between one point & another

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