Energy, Power And Climate Change Flashcards
Width of the arrow is proportional to the energy it carries
Sankey diagram
Flow of … Tends to equalise … And deprives us from the opportunity to do work
Thermal energy / temperature
Electricity production takes place in
Electric generators
A generator converts mechanical energy (rotational energy from coil) to
Electrical energy
Finite sources such as fossil and nuclear fuels
Non renewable
Include solar and tidal energy
Renewable sources
The energy that can be obtained from a unit mass of the fuel
Energy density
Relatively cheap, high power output, variety of uses but cause environmental problems
Fossil fuels
Typical fuel for nuclear reactions; critical mass must be present to induce chain reaction
Uranium 235
Slow neutrons down in nuclear reactions in order to avoid captured by fuel
Moderator
Isotope that does not occur naturally, created when U238 is bombarded with neutrons from fission reaction
Plutonium 239
Plasma from nuclear fusion reactions is magnetically contained in
Tokamak
Has fewer radiation wastes
Fusion
All bodies that are kept at some absolute (kelvin) temperature T radiate energy in the form of electromagnetic waves
Black body law
Power radiated by a body is governed by the
Stefan-Boltzmann law
Amount of energy per second (i.e power) radiated by a body depends on its surface area, absolute temperature, and the properties of the surface.
P = eoAT^4
When the constant of emissivity e of the surface is 1, …. A theoretical body that is a perfect emitter
Black body
Most energy is radiated at specific wavelengths, determined by …. Of the body. The higher the …., the shorter the wavelength
Temperature
The relation between the temperature and the peak wavelength (of curve), the wavelength at which most of the energy is emitted, is given by
Wien’s law
May be considered to radiate as a perfect emitter (i.e as a black body)
The sun
Ratio of the power of radiation reflected or scattered from the body, to the total power incident on the body
Albedo
Warming of the earth caused by infrared radiation emitted by the surface which is absorbed by various gases in the atmosphere and partially radiated towards the surface
Greenhouse effect
Infrared photons travelling through these gases will be absorbed; which means that the molecules will be excited to higher energy levels
Water vapour, carbon dioxide, methane and nitrous oxide
When melted will not result in change of sea level because of Archimedes’ fluid mechanics
Sea ice
Fractional change in volume per unit temperature change
Coefficient of volume expansion
