Youre in Charge

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Youre in Charge
(Edexcel)
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Wind Power
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Tidal Power
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Wave Power
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Hydroelectric Power
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Biomass
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Renewable energy sources summary
Advantages
Disadvantages
Zero fuel costs
Unreliable (except for hydroelectric)
Dont produce pollution
Expensive to build
Hydroelectric is good for a sudden demand
Deforestation is a cause of the Greenhouse Effect
Tidal barrages destroy the habitats of wading
birds and hydroelectric schemes involve flooding
farmland
Solar is good for remote locations (e.g.
satellites)
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Other renewable options
Geothermal energy water is heated using heat
given off by _________ rocks underneath the
surface of the Earth
Although renewable fuels are ____, the energy we
get from them is _______. This means that we
have to spend a lot of money on generators to
make them worthwhile. This is why solar panels
are only used in small things (like calculators)
or extremely remote locations (like
____________). Solar cells are not very ________.
Words dilute, radioactive, free, satellites,
efficient, light
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DC Motors
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Power and fuses
Power is the rate of doing work. It is
measures in Watts, where 1W 1 Joule per second.
The amount of power being used in an electrical
circuit is given by
Power voltage x current in W in V
in A
Using this equation we can work out the fuse
rating for any appliance. For example, a 3kW
(3000W) fire plugged into a 240V supply would
need a current of _______ A, so a _______ amp
fuse would be used (fuse values are usually 3, 5
or 13A).
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Power and fuses
Copy and complete the following table
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The Cost of Electricity
Electricity is measured in units called kilowatt
hours (kWh). For example
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The Cost of Electricity
To work out how much a device costs we do the
following
Cost of electricity Power (kW) x time (h) x
cost per kWh (p)
For example, if electricity costs 8p per unit
calculate the cost of the following

• A 2kW fire left on for 3 hours
• A 0.2kW TV left on for 5 hours
• A 0.1kW light bulb left on for 10 hours
• A 0.5kW hoover left on for 1 hour

48p
8p
8p
4p
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Energy changes
To describe an energy change for a light bulb we
need to do 3 steps

• What are the energy changes for the following?
• An electric fire
• A rock about to drop
• An arrow about to be fired

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Conservation of Energy
In any energy change there is ALWAYS some waste
energy e.g. a light bulb
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Efficiency
Efficiency is a measure of how much USEFUL energy
you get out of an object from the energy you put
INTO it.
For example, consider a TV
Light (80J)
Electrical Energy (200J)
Sound (40J)
Heat (?)
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Some examples of efficiency

• 5000J of electrical energy are put into a motor.
  The motor converts this into 100J of movement
  energy. How efficient is it?
• A laptop can convert 400J of electrical energy
  into 240J of light and sound. What is its
  efficiency? Where does the rest of the energy
  go?
• A steam engine is 50 efficient. If it delivers
  20,000J of movement energy how much chemical
  energy was put into it?

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House insulation
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House insulation

• Which type of insulation costs the most?
• Which type of insulation is the most effective?
• Which type is the most cost effective?
• Which type pays for itself after 40 years?

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Wiring a plug
Earth wire
Live wire
Fuse
Neutral wire
Cable grip
Insulation
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Fuses
Fuses are _______ devices. If there is a fault
in an appliance which causes the ____ and neutral
(or earth) wire to cross then a ______ current
will flow through the _____ and cause it to
_____. This will break the _______ and protect
the appliance and user from further _____.
Words large, harm, safety, melt, live, circuit,
fuse
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Earth wires
Earth wires are always used if an appliance has a
_____ case. If there is a _____ in the
appliance, causing the live wire to ______ the
case, the current _______ down the earth wire
and the ______ blows.
Words fuse, fault, metal, surges, touch
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Circuit breakers
Residual Current Circuit Breakers (RCCBs) are
often used with fuses. They have some advantages
over fuses

• They are safer they dont get hot
• They react more quickly
• They can be switched off for repairs
• They are easy to reset
• Each RCCB is attached to a certain circuit, so if
  one switches off you can see which circuit has a
  fault