Download GE lesson 5

Generating Electricity 5
Syllabus Specifications
3.2 d Sankey diagrams to show energy transfers; energy efficiency in terms of input energy in terms of input energy and energy usefully transferred in a range of contexts including
electrical power generation and transmission.
% 𝒆𝒇𝒇𝒊𝒄𝒊𝒆𝒏𝒄𝒚 =
𝒆𝒏𝒆𝒓𝒈𝒚 𝒑𝒐𝒘𝒆𝒓 ) 𝒖𝒔𝒆𝒇𝒖𝒍𝒍𝒚 𝒕𝒓𝒂𝒏𝒔𝒇𝒆𝒓𝒓𝒆𝒅
𝒕𝒐𝒕𝒂𝒍 𝒆𝒏𝒆𝒓𝒈𝒚 𝒑𝒐𝒘𝒆𝒓 𝒔𝒖𝒑𝒑𝒍𝒊𝒆𝒅
𝒙 𝟏𝟎𝟎
Calculating efficiency
Example
25 J
light
100 J
electrical
75 J
Heat
Energy circus
• Find the efficiencies of 5
common appliances
• You have 1 minute at each
station.
Sankey diagrams can be drawn to scale e.g.
An energy efficient
light bulb produces 7J
of light for every 10J
input.
10 Joules
electrical
energy
input
7 squares = 7 joules – light
energy
3 squares = 3 joules – heat
energy
1 square is 1 joule of energy
Efficiency
1
5
Complete this Sankey
diagram for a coal fired
power station
Energy In:
100 %
Chemical
Hair dryer
100 % electrical
50 % kinetic
40 % heat
10 % sound
Draw Sankey diagram
Energy Out:
40 % Electrical
50 % Heat
10 % Sound
Answer
2
TV
Energy transferred = power
x time
kilowatt hours
kilowatts
hours
How efficiency is the hair dryer?
Answer
6
Lamp
Label the energy
The TV is rated at 900 Watts
How much will it cost to watch it for 2 hours? ( 1 kilowatt hour = 20p)
3
Toy
Efficiency = Energy usefully transferred x 100
Total energy supplied
How efficient is this toy?
4
Heater
Elastic potential = 200 Joules
Sound
= 30 Joules
Heat
= 70 Joules
Movement
= 100 joules
This heater is rated at 3 kilowatts
It is turned on for 3 hours
How much does it cost?
Mains electricity is 230 V
Calculate the current
Power = voltage
Watts
Volts
x current
Amps
Calculate the efficiency
Answer
Answer
Percentage
Decimal
7
Radio
Answer
Energy in:
200 Joules electrical
Answer
Energy out:
40 Joules - light
80 Joules - sound
80 Joules - heat
Draw a Sankey diagram
Energy splat! 1
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What is the
useful
energy ?
Energy splat! 2
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What is
the useful
energy?
Energy splat! 3
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What is the useful
energy produced in
the moving air?
Energy splat! 4
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy is
generated
from a wind
turbine?
Energy splat! 7
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy is
generated?
Energy splat! 8
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy is
used up by
the kettle?
Energy splat! 9
Kinetic energy
Sound energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy is
generated?
Energy splat! 11
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy is
stored in the
match?
Energy splat! 12
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
An object high
above the Earth
has lots of this
type of energy!
Energy splat! 13
Kinetic energy
Heat energy
Gravitational potential
energy
Electrical energy
Chemical energy
Light energy
What type of
energy does
coal contain?
Energy splat! 14
100 joules
75%
20%
50 joules
200 joules
1,000 joules
150 J
light
200 J
in
What is the
efficiency
50 J
in
Energy splat! 15
100 joules
25 joules
20%
50 joules
200 joules
1,000 joules
300j
light
500j
in
How much
waste
energy?
?? j
waste