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Monday, March 9, 2009
Sunday, March 8, 2009
Monday Lesson
Homework: Hand in Coached Exam - Last warning
Write a summary the advantages of AC over DC for power transmission. Summarize the conflict between Edison and Westinghouse.
Section One Generators and Power distribution.
Context:
Electricity authorities use high-voltage transmission lines and transformers to distribute electricity to homes and industries around each state. Voltages can be as high as 5 x 105 volts from power stations but by the time this reaches homes, the electricity has been transformed to 240 volts. While it is relatively economical to generate electric power at a steady rate, there are both financial and environmental issues that should be considered when assessing the long-term impact of supplying commercial and household power.
Section Two Exam Practice
Exam Practice answer these questions.
Compare Centripal Force and Kinetic Science.
- Copy this question, Highlight the verb, Write Heading Comparison table, Write in Header, Property, Centripital, Kinetic, Comparison.
Discuss the statement "Michelson Morley believed in Aether and the Scientific Method. Their experiments lead to the abandonment of Aether"
- copy this question, highlight verb, write heading "Discussion", State what happened, comment on the statement.
Explain how the relativistic space travel could allow us to reach Stars 1000Ly away but there is little prospect of reaching these speeds.
-copy question, highlight verb, Write heading explanation, Write the time dilation equation, explain with an example, Write the mass dilation equation and the Energy equivalence equation, with an example. Finish
Compare Generators and DC Motors.
-copy and highlight, produce a table.
Write a summary the advantages of AC over DC for power transmission. Summarize the conflict between Edison and Westinghouse.
Section One Generators and Power distribution.
Context:
Electricity authorities use high-voltage transmission lines and transformers to distribute electricity to homes and industries around each state. Voltages can be as high as 5 x 105 volts from power stations but by the time this reaches homes, the electricity has been transformed to 240 volts. While it is relatively economical to generate electric power at a steady rate, there are both financial and environmental issues that should be considered when assessing the long-term impact of supplying commercial and household power.
- describe the differences between AC and DC generators
- discuss the energy losses that occur as energy is fed through transmission lines from the generator to the consumer
- assess the effects of the development of AC generators on society and the environment
- § gather secondary information to discuss advantages/disadvantages of AC and DC generators and relate these to their use
§ analyse secondary information on the competition between Westinghouse and Edison to supply electricity to cities
§ gather and analyse information to identify how transmission lines are:
– insulated from supporting structures– protected from lightning strikes
Section Two Exam Practice
Exam Practice answer these questions.
Compare Centripal Force and Kinetic Science.
- Copy this question, Highlight the verb, Write Heading Comparison table, Write in Header, Property, Centripital, Kinetic, Comparison.
Discuss the statement "Michelson Morley believed in Aether and the Scientific Method. Their experiments lead to the abandonment of Aether"
- copy this question, highlight verb, write heading "Discussion", State what happened, comment on the statement.
Explain how the relativistic space travel could allow us to reach Stars 1000Ly away but there is little prospect of reaching these speeds.
-copy question, highlight verb, Write heading explanation, Write the time dilation equation, explain with an example, Write the mass dilation equation and the Energy equivalence equation, with an example. Finish
Compare Generators and DC Motors.
-copy and highlight, produce a table.
Wednesday, March 4, 2009
Corrected Homework
There is now in and out trays inside the science staff room.
Place your homework on the top one, and take the corrected work out the bottom. There is a sign in book where you can write in what you wanted corrected, and will log comments.
From the Practice Half yearly here are some hints:
Good and Bad eddy currents- the bad ones are from coiled extention leads, losses in anything AC electrical.
When you have a question, draw realistic diagram. If you draw a 20 deg triangle you can see that the horizontal velocity has to be bigger than the vertical
Torque is a vector quantity
Work done on an object is the amount of work put into an object, done by an object is the amount of work out.
It is now a requirement to circle the verb in a question. Then use it the answer. If possible use a table.
A comparison table has Three columns Object one, Object two, Comparison of Object one to two.
Four columns are even better where you list the concept in the first.
Compare Earth and Mars gravitational effects
G Effect Earth Mars Comparison
g 9.8 3.6 Earth is bigger
Atmosphere Large Small Mars has lost is atmosphere
escape V 4000 1000 Mars is smaller
Place your homework on the top one, and take the corrected work out the bottom. There is a sign in book where you can write in what you wanted corrected, and will log comments.
From the Practice Half yearly here are some hints:
Good and Bad eddy currents- the bad ones are from coiled extention leads, losses in anything AC electrical.
When you have a question, draw realistic diagram. If you draw a 20 deg triangle you can see that the horizontal velocity has to be bigger than the vertical
Torque is a vector quantity
Work done on an object is the amount of work put into an object, done by an object is the amount of work out.
It is now a requirement to circle the verb in a question. Then use it the answer. If possible use a table.
A comparison table has Three columns Object one, Object two, Comparison of Object one to two.
Four columns are even better where you list the concept in the first.
Compare Earth and Mars gravitational effects
G Effect Earth Mars Comparison
g 9.8 3.6 Earth is bigger
Atmosphere Large Small Mars has lost is atmosphere
escape V 4000 1000 Mars is smaller
Sunday, March 1, 2009
Generators
Revision
Force on currents = motor
Force on currents = motor
- wire in B field
- parrallel wires
- loop creating torque - DC motors make the inner rotation solenoid fight the field
Faradays Law
1. Back voltage = - time differential of B*a
2. wire cutting a field is a battery
Lenz's law - practical Faraday - Eddy currents make a solenoid that resists motion. Motion turns into electrical energy and heat
- dropping magnet - solenoids are made that arrest fall turning energy into heat
- spinning disk - two solenoids are made opposing entry of a magnet, and dragging it back
- inducation furnace for cooking, eddy current heats metal
Homework SUMMARIZE CHAPTER 8 finish half yearly for correction.
Generators
1. Direction of current through (1) + charge right hand slap (2) lenz law
2. Slip AC- Split DC
3. Rotating faster = higher frequency and higher voltage
Transformers
more loops- more volts
Step up for efficient power transmission. P = I x I x R
eddy currents reduced by lamination. layer of insulators.
Step down to make voltage Kid friendly.
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About Me
- drhill
- I come from a Science family: My father Geoffrey Hill was Australia's first computer programmer on CSIRAC the fourth computer in the world. He is credited with invention of Computer music and the development of “Interprogram” a language before Basic. My PhD is in Atomic and Molecular Physics. I have researched the activated oxygen layer above the ozone layer, and 'Assigned' the world's smallest molecule. At the University of Toronto I researched high power UV lasers. I have specialized in automation in fibre optics. This developed into research in Machine Intellect and Robots. I have enjoyed work as an Explainer with Questacon and my time as a part-time soldier. I currently teach High School Science at Epping Boys’ High.