P8.2 - Powering Earth Flashcards
describe 2 examples of non-renewable energy sources (and how they work)
fossil fuels - burned to heat up water within a power plant
nuclear fuel - radiation released also heats up water
what are the steps within a power plant to produce electricity?
fuel (nucleur/fossil) causes heat to be generated
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heat causes water to turn to steam
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steam turns the turbine
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turbine turns the generator
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generator produces electricity
describe 5 types of renewable energy sources (how they work)
biofuel - burning organic material as fuel
wind - using wind to turn turbines (instead of steam)
hydroelectricity - controlling the water falling and it turns the turbine = electricity
tides - similar as hydroelectric (but the sea coming in and out)
solar - using the sun’s energy to generate electricity/heat a house
what are the main energy sources for:
(a) transportation
(b) heating
(c) generating electricity
(a) - fossil fuels (crude oil
- biofuels (bioethanol)
(b) - fossil fuels (for heating up the boiler)
- solar heating (or thermal solar)
(c) - mainly coal (36%)
- gas (27%)
- nuclear (20%)
- renewable (14.9%)
what are the two types of solar panels?
1) solar cells (photovoltaics) - convert sunlight energy to electrical energy
2) solar panels - convert sunlight to heat energy for heating
pos/neg of:
- fossil fuels
P - reliable source of energy (will always burn)
- cost effective (not too expensive to set up)
N - releases greenhouse gases
- non renewable
pos/neg of:
- nuclear power
P - extremely energy dense (produced x6000 more energy than fossil fuels
- no greenhouse gases
N - radioactive waste hard to dispose of
- very dangerous (if explodes is disasterous)
- non renewable
how do biofuels work?
- fuel comes from a recently living/living organism (gas from manure, sugar cane, ethanol)
- carbon neutral (CO2 released when burning is reabsorbed when new plants grow)
- does release CO2, but no NET RELEASE of greenhouse gases in the atmosphere *
how did the industrial revolution affect out use of energy resources?
- increased use of coal (machines in factories + steam trains)
how has new transport (cars + planes) changed our use of energy?
from around 1920, more increase in oil (for cars and planes)
what energy supply has remained relatively constant?
biofuels (trees)
state some issues with energy supply
- as developing countries become more wealthy, they would require more energy as well
- fossil fuels are finite (and hard to reach as it is becoming more scarce)
- burning fuels produces greenhouse gases (climate change)
what is a problem with renewable energy sources?
- they can be expensive to set up (and more pollution may happen when constructing it)
- so it needs to last long enough to produce enough energy to counter that + its cost to set up
How many milliseconds in one second?
1000
recall that, in the national grid,
Spec
recall that, in the national grid, electrical power is transferred at high voltages from power stations, and then transferred at lower voltages in each locality for domestic use
what are step-up and step-down transformers used to change (and when)?
the potential difference as power is transferred from power stations
explain how the national grid is an efficient way to transfer energy
- high voltages in power lines, which reduces current flowing through wires
- this reduces energy lost to the surroundings
- and so transfer of energy is more efficient
what remains constant when a potential difference is increased/decreased from a transformer?
the total power transferred
equation to calculate step-up/step-down transformer?
Vp x Ip = Vs x Is
how to calculate power (in terms of current and resistance)?
P = I^2 x R
in terms of the domestic supply in the UK what is the: a) potential difference b) type of current c) frequency
a) 230V
b) ac current
c) 50Hz
difference between direct and alternating current
- AC’s potential difference continuously switches, as does its direction of current
- DC has a fixed (positive) amount
what is a source of DC current?
battery, cells
name the colour of
a) live wire
b) neutral wire
c) earth wire
a) brown
b) blue
c) green-yellow
out of the live, neutral and earth wire
which one is the odd one out and why?
earth wire, as it is not connected to the mains (connected to a pole in the ground outside)
function of
a) live wire
b) neutral wire (and how)
c) earth wire (and how)
a) carries voltage from mains to appliance
b) completes the circuit by providing a path back to the electrical panel
c) prevents appliance being live, has low resistance so current goes from casing through earth wire into ground
potential difference between
a) live and neutral wire
b) live and earth wire
c) neutral and earth wire
a) 230v
b) 230V
c) 0 V
what does it mean when an appliance is live?
live wire becomes loose and touches the metal casing, so then current flows on metal casing/surface of appliance, and if you touch it a current flows through you
danger of providing connection between live wire and earth wire?
they would have such a great potential difference between them that a large current would be created which can provide a lethal shock to the person
explain the protection offered by insulation of devices
- case can be made of plastic
- so no current can flow through case to you
- called ‘double insulation’
- so an earth pin is not necessarily needed
