IB+DP+Topic+8+Energy+production

If you repeat something enough times, it comes to feel good and true. media type="youtube" key="cebFWOlx848" width="560" height="315" The Illusion of Truth Published on 21 Jul 2016

8.1 - Energy sources // ** Nature of science: ** // Risks and problem-solving: Since early times mankind understood the vital role of harnessing energy and large-scale production of electricity has impacted all levels of society. Processes where energy is transformed require holistic approaches that involve many areas of knowledge. Research and development of alternative energy sources has lacked support in some countries for economic and political reasons. Scientists, however, have continued to collaborate and share new technologies that can reduce our dependence on non-renewable energy sources. (4.8)

// ** Understandings: ** // • Specific energy and energy density of fuel sources • Sankey diagrams • Primary energy sources • Electricity as a secondary and versatile form of energy • Renewable and non-renewable energy sources

// ** Applications and skills: ** // • Solving specific energy and energy density problems • Sketching and interpreting Sankey diagrams • Describing the basic features of fossil fuel power stations, nuclear power stations, wind generators, pumped storage hydroelectric systems and solar power cells • Solving problems relevant to energy transformations in the context of these generating systems • Discussing safety issues and risks associated with the production of nuclear power • Describing the differences between photovoltaic cells and solar heating panels

//** International-mindedness: **// • The production of energy from fossil fuels has a clear impact on the world we live in and therefore involves global thinking. The geographic concentrations of fossil fuels have led to political conflict and economic inequalities. The production of energy through alternative energy resources demands new levels of international collaboration.

• The use of nuclear energy inspires a range of emotional responses from scientists and society. How can accurate scientific risk assessment be undertaken in emotionally charged areas?
 * // Theory of knowledge: //**

// ** Guidance: ** // • Specific energy has units of J kg–1; energy density has units of J m–3 • The description of the basic features of nuclear power stations must include the use of control rods, moderators and heat exchangers • Derivation of the wind generator equation is not required but an awareness of relevant assumptions and limitations is required • Students are expected to be aware of new and developing technologies which may become important during the life of this guide

• Power = energy/time • Power = 1 / 2(Aρv 3 )
 * // Data booklet reference: //**

• Aim 4: the production of power involves many different scientific disciplines and requires the evaluation and synthesis of scientific information • Aim 8: the production of energy has wide economic, environmental, moral and ethical dimensions
 * // Aims: //**

**//Sources of Energy//** Natural resources: Any materials found on Earth that are used by humans. In most instances, the Sun is the prime energy source for world energy. In the Sun, energy is released by nuclear fusion. The Sun is the source of energy for all our energy resources except geothermal, nuclear and tidal. Electrical energy may be produced by rotating coils in a magnetic field. Energy sources used to provide the energy to rotate the coils.

//__PRINCIPLE OF CONSERVATION OF ENERGY:__// Energy is never __ created __ nor __ destroyed __. It just changes from one __ form __ to __ another __. In any process that involves energy transformations, however, the energy that is transferred to the surroundings (thermal energy) is no longer available to perform useful work. This ‘__**lost**__’ energy is known as __**degraded energy**__. Image from [|U.S. Energy Information Administration]

__Non-Renewable energy resources__ **FUEL:** Material that releases energy as it changes chemically. ex) coal, oil, wood, gas, charcoal, methane, petrol cf) E nergy resources: Any resources that release energy, especially resources/materials that humans use to generate electrical energy.
 * Fossil fuels **

PRACTICE 1: Describe the origin of fossil fuels. Energy density cartoon for [|xkcd]
 * · Specific energy is how much energy (J) released per unit mass (kg) of a fuel consumed. Its units are J kg-1.**
 * · Energy density is how much energy (J) released per unit volume (m3) consumed. Its units are J m-3.**

EXAMPLE 1: Fission of each uranium-235 produces 3.5 x 10^-11 J of energy. The density of U-235 is 1.8 x 10^4 kg m^-3. Calculate the Specific Energy and the Energy Density of U-235. SOLUTION: (a) m = (235 u) (1.66 x 10^-27 kg u^-1) = 3.90 x 10^-25 kg Specific Energy = 3.5 x 10^-11 J / 3.90 x 10^-25 kg = 9.0 x 10^13 J kg^-1 (b) Energy Density = (9.0 x 10^13 J kg^-1) (1.8 x 10^4 kg m^-3 = 1.6 x 10^18 J m^-3

Image from [|electricityasia.wordpress.com]

 * [|Energy density of common fuels] **

Efficiency = Output / Input
EXAMPLE 2: Coal has a specific energy of 32.5 MJ/ kg. If a city has a coal-fired power plant that needs to produce 30.0 MW of power, with an efficiency of 25%, how many kilograms of coal are needed daily? SOLUTION: efficiency = Output / Input 0.25 = 30.0 MW /input Input = 120 MW But 1 day = 24 x 3600 s = 86400 s so that Input = (120 MJs^-1)(86400 s) = 10,368,000 MJ  Input = (10368000 MJ)(1 kg / 32.5 MJ) = 320000 kg

 __Energy resources - Springer 2016__

Sankey diagrams:
Energy flow diagrams for various systems including fossil fuel power production and non fossil fuel power production. Energy degradation in systems can be shown with an energy flow diagram called a Sankey diagram. EXAMPLE 3: Image from [|www.mdpi.com] From conservation of energy we see that at each interface, the energy in must equal the energy out.
 * Find the energy values for each of the degradations in the Sankey diagram.

EXAMPLE 4: PRACTICE: Suggest(Give reasons why) the burning of fossil fuels may lead to an increase in the temperature of the surface of the Earth. SOLUTION: Burning fossil fuels releases more Greenhouse gasses such as CO2, CH4, N20 and H2O into the atmosphere than would already exist. This will lead to an increase in the rate of energy being absorbed and re-radiated. This results in Earth's temperature rising further. EXAMPLE 5:
 * Create a Sankey diagram of Coal fueled power plant and determine the energy efficiency of the power plant.
 * Create a Sankey diagram for a typical nuclear reactor:

**Energy releases in nuclear power station** In a chemical change such as burning, atoms get arranged. Energy is released as electrons settle into different positions in atoms. In radioactive decay, nuclear particles get rearranged. The energy released per atom is around a million times greater than that from a chemical change such as burning. In fission, lots more atoms are involved every second than in natural decay. Energy is released much more rapidly. How nuclear power plant works? from nuclear power.net media type="youtube" key="VJfIbBDR3e8" width="560" height="315" How nuclear energy works [|ENECeducation] Uploaded on 30 Dec 2009 [|Why is uranium-235 ideal for nuclear-power?] science.howstuffworks.com/
 * What are Nuclear Accidents?
 * How are they Classified?
 * The Dangers Associated with them?
 * How to prepare for and protect from nuclear accidents?
 * How to determine your RISK LEVEL of them?

Nuclear fission
Natural uranium is a dense radioactive metal. It is mostly made up of two isotopes: uranium-238(over 99%) and uranium-235(less than 1%). The nucleus becomes highly unstable and splits into two lighter nuclei, shooting out two or three neutrons as it does so. The splitting is called fission. It releases energy which throws the bit apart. nuclear fission from cyberphysics.co.uk

media type="youtube" key="yTkojROg-t8" width="560" height="315"

Fission And Fusion [|The Science Channel] Uploaded on 22 Jul 2009

The following quotes show some peoples’ opinions on whether we should build more nuclear power stations in the UK. Colour code them to show which are quotes for the building of more nuclear power stations and which are against.
 * __ Opinions on nuclear power __ **

[|Understanding Nuclear power plants total station black out] from youtube.com

Is Nuclear Power Safe BBC Documentary media type="youtube" key="kQurxqYJ_dE" width="560" height="315"

**Task 1 :Do we need Nuclear Power?** ** Individual research. Tuesday 7 March 2017 ** Describe advantages and disadvantages of using Nuclear Power. You must include the basics of "How a Nuclear Reactor Works" and the dangers of an accident at a nuclear plant such as the handling of nuclear material, the operating of the plant and disposal of the nuclear waste. Lists of bullet points are acceptable. Submit your research papers at the end of class.


 * Task 2 :Do we need Nuclear Power Plant? **** Debate preparation - Thursday 9 March 2017 **

1st group for the debate Fisherman - Kim Thach, Greenpeace -Giang Tien, Historian - Won Jun, Property developer -Cheng Chun, Quang Huy || C -Lina, F -Woo Jin G -Kei Yokokura H -Edward P -Thien Duy, || C -Naoki, F -Tuan Hung G -Ji Hun H -Nguyen Duc, P -Nhat Minh, ||
 * Group name/ Make your own || Anything || Anti-Physics-Kei's idea || G3 ||
 * Member of each group ||  ||   ||   ||
 * Roles taken || Councillor - Thanh Dat

During the lesson, each group will show their debate and make a decision whether to build the Nuclear Power Station in your village or not. This debate will be graded and used for assessment purposes. Please record your group debate and upload it on ManageBac. Due Monday 13 March 2017 (Homework) Thanks for uploading your debates which clearly expressed your feelings on this important matter. Please find the attached debates. Please listen to yourself and other member's opinions then find what you have done well and what improvements you can make.
 * [[file:freempton information guide.docx]] || [[file:councillor.docx]] || [[file:fisherman.docx]] || [[file:greenpeace.docx]] || [[file:historian.docx]] || [[file:property developer.docx]] ||
 * Debate - Monday 13 March 2017 **

In the article you will write on Monday, 20th March, Ms. Lee needs to read more examples and support materials of your key ideas. Specific information such as amount of energy generated, costs of primary source, examples of percentages that cover electrical energy demands in a city would be good evidence that can support your opinion. Good luck with your articles.

Final group for the poster - Thursday 16th March 2017
 * Group name/ Make your own || 1 || 2 || 3 || 4 ||
 * Member of each group || Cheng Chun, Kim Thach, Ji Hun, Quang Huy || Kei Yokokura, Edward,Thien Duy, Lina || Tuan Hung, Thanh Dat, Woo Jin, Giang Tien || Won Jun, Naoki, Nguyen Duc, Nhat Minh ||
 * Roles taken: Basic examples:
 * Pros and Cons: renewable vs non renewable -
 * Primary and secondary source of energy -
 * Sankey diagram -
 * Description of basic features of nuclear power -
 * Specific energy and energy density of fuel sources -
 * Discussing safety issues and risks associated with the production of nuclear power -
 * Solving problems relevant to energy transformations in the context of these generating systems - ||  ||   ||   ||   ||

Inside a Japanese power station from youtube.com media type="youtube" key="E1P6Q1e6gCg" width="560" height="315"

[|REPORT ABOUT NUCLEAR MELTDOWN DURING AN EARTHQUAKE] (Japan, March 2011)

[|BBC VISITS FUKUSHIMA IN FEB 2012]

[|NUCLEAR ACCIDENT SIMULATION]

How does a Nuclear Power Plant work? media type="custom" key="29005709" Phet [|Nuclear Fission simulator] from University of Colorado Image from [] Heat exchanger is where the thermal energy from the reactions is transferred to the water. This allows the nuclear reactions to take place in a safe chamber sealed off from the rest of the environment. [|CHAIN REACTION APPLET] [|SIMULATION OF NUCLEAR FISSION REACTOR] PRACTICE: Explain why it is advantageous to have a submarine which is nuclear powered, as opposed to diesel. SOLUTION: (1) Nuclear reactors don’t use oxygen, so the submarine can stay under water for months at a time. (2) Nuclear fuel is extremely compact for the amount of energy it contains. Thus the submarine can cruise far before refill.
 * Control rods || The moderator slows down the neutrons || Fuel pellets are bundled || The core ||
 * [[image:nothingnerdy/fission_control_rods.jpg]] || [[image:nothingnerdy/fission_moderator.jpg width="354" height="203"]] || [[image:nothingnerdy/fission_fuel.jpg width="358" height="202"]] || [[image:nothingnerdy/fission_reactor_real.jpg]] ||

Your assessed task for this sub-topic will be to write a newspaper article about nuclear power plant to be displayed on the wall. This should include materials to support your group agreement that you made from task 2. THIS WILL BE WRITTEN UP IN CLASS. Your homework is to do some research to prepare for this task. You need to find and PRINT OUT, COPY or MAKE NOTES ON at least three sources. You must bring your research to the lesson – YOU WILL NOT BE ALLOWED TO LEAVE THE LESSON TO GO AND PRINT THINGS. You MAY annotate, highlight, underline, add Post-IT notes, etc to your research. You will be allowed to use this in the lesson. Your verbal presentation will follow this task and will be graded and reflected to your report card.
 * Task 3: Do we need Nuclear Power Plant? Group presentation preparation. - Thursday 16 March 2017 **

You must use graphs and pictures/diagrams in your display and understanding of • Specific energy and energy density of fuel sources • Sankey diagrams • Primary energy sources • Electricity as a secondary and versatile form of energy • Renewable and non-renewable energy sources • Describing the basic features of nuclear power stations and drew a comparison between fossil fuel and nuclear power stations • The description of the basic features of nuclear power stations must include the use of control rods, moderators and heat exchangers • Solving problems relevant to energy transformations in the context of these generating systems • Discussing safety issues and risks associated with the production of nuclear power • Electricity as a secondary and versatile form of energy // ** Guidance: ** // • Specific energy has units of J kg –1 ; energy density has units of J m –3 • Students are expected to be aware of new and developing technologies which may become important during the life of this guide Bibliography must be included in all research tasks. Due: Writing on an article on Monday 20th March, ** Group presentation Tuesday 21st ** March 2017. Both will take place in class.

Additional support material: gep17.doc - Find it on ManageBac

**Renewable resources** can be __ replaced __ in a reasonable amount of time.
It is replaceable by natural process continuously and the source will not run out for a very long time.

PRACTICE: Describe the energy transfers involved and outline appropriate uses of a photovoltaic cell and a solar heating panel. 1) Photo-voltaic cells convert the solar radiation directly into a potential difference (voltage) by using a semi-conductor. (Solar energy -> Electrical energy) Unfortunately, individually they can only provide a very small voltage and current. 2) Active Solar Heater captures as much thermal energy as possible. (Solar energy -> Thermal energy) The hot water it produces can be used domestically and saves the use of electrical energy.
 * Solar power **

Have you spotted the Earth in the solar system? Can you describe nuclear fusion?How does fusion power the Sun?
 * Challenge questions;**

**Hydroelectric power** PRACTICE: Describe the main energy transformations that take place in hydroelectric schemes. Gravitational potential energy in a hydroelectric dam or a reservoir converted to kinetic energy as water flows down hill. This kinetic energy of falling water turns the blades of a turbine which turn a loop of wire inside a magnet generating electrical energy.

PRACTICE: 1. Distinguish between different hydroelectric schemes that are based on: • water storage in lakes • tidal water storage • pump storage. 2. Solve problems involving hydroelectric schemes.

EXAMPLE 6: A reservoir for a hydroelectric dam is 1700m x 2500m x 50m. This flows 75m down through a tunnel. (a) Calculate the potential energy yield. SOLUTION: ·The total volume of water is V = 1700(2500)(50) = 2.125 x 10^8 m^3 ·The mass of the water is m = rV = (1000 kgm^-3)(2.125 x 10^8 m^3) = 2.125 x 10^11 kg ·The average water height is h = 75 + 50 / 2 = 100 m ·The potential energy yield will then be Potential energy = mgh = (2.125 x 10^11)(10)(100) = 2.125 x 10^14 J

(b) If the water flow rate is 25 m3 per second, what is the power provided by the moving water? SOLUTION: ·Each cubic meter has a mass of 1000 kg. ·Thus each second m = 25(1000) = 25000 kg falls. ·Thus each second the reservoir relinquishes E P = mgh = (25000)(10)(100) = 2.5 x 10^7 J ·Since power is measured in W (or J s-1) the power provided is 2.5 x 10^7 W = 25 MW

(c) If the water is not replenished, how long can this reservoir produce power at this rate? SOLUTION: ·The total volume of water is V = 1700(2500)(50) = 2.125 x 10^8 m^3 ·The volume flow rate is 25 m^3 s-1 ·Thus the time is given by t = (2.125 x 10^8 m^3) / (25 m^3 s^-1) = 8.5 x 10^6 s = 2361 h = 100 d

PRACTICE: Describe the principle of operation of an oscillating water column (OWC) ocean-wave energy converter. Energy from a water wave can be extracted in a variety of different ways, but only a description of the OWC is required. "The water level within the water column increases and decreases with waves coming in resulting in compression and decompression of air. Wells-turbines are ideal for the purpose of converting this into energy, because the turbines rotate the same way independent of the direction of the airflow. A generator converts this mechanical energy into useful electricity." Article extracted from [|energy informative].
 * Wave power **

[|Turning Ocean Waves Into Renewable Energy] from TERRAMAR PROJECT

Determine the power per unit length of a wavefront, assuming a rectangular profile for the wave. Solve problems involving wave power Power per unit length = ½ A 2 ρgv A is amplitude of wave ρ is density of water g is acceleration due to gravity v is speed of water

PRACTICE: A wave generator produces a power per unit length of 4.0kW m -1 for waves of amplitude //**A**// and speed **//v//**. The efficiency of the generator is constant. What would be the power per unit length obtained from waves of amplitude 2**//A//** and speed 2**//v//** ? SOLUTION: Power per unit length = (1/2)A 2 ρgv Thus power increases 4 times as (2A)2 is 4A. Also it increases 2 times from v to 2v. This gives an overall increase of 4 x 2 = 8 times. as such 8 x ( 4.0kW m-1) = 32.0kW m-1 PRACTICE: Waves having an amplitude of 4.0 m approach to a beach at a rate of one every 5.0 seconds. The wave crests are 60. meters apart. (a) How much wave power is there, per unit length? (b) How much energy is there on a 25 km coast? SOLUTION: (a) v = f x λ = λ / T = 60/5 = 12 m/s power per length = (1/2)A2ρgv = (1/2) 4 x 4 x 1000 x 10 x12 = 96000 W/m = 960 kW/m (b) power = ( 960000 W/m ) x 25000 m = 2.4 x 10 10 J/s (W)

**Wind power** [|Energy 101 Wind energy] [|Energy & Environmental News] Uploaded on 16 Dec 2011 || media type="youtube" key="8PE69jcleKg" width="560" height="315" Facts About Wind Energy [|AboutFacts] Published on 9 Nov 2013 || Sunlight is absorbed by Earth’s surface and then Earth radiates heat which them warms up the air above. Hot air rises as it is less dense and cooler air rushes in, causing wind. Wind turns the blades of a wind turbine generating electricity as the blades turn a loop of wire inside a magnet.
 * media type="youtube" key="niZ_cvu9Fts" width="560" height="315"

Determine the power that may be delivered by a wind generator, assuming that the wind kinetic energy is completely converted into mechanical kinetic energy, and explain why this is impossible. Solve problems involving wind power. Power = ½ (Aρv 3 ) A is Area of air blowing in ρ is density of air v is speed of air

EXAMPLE 7: Determine the power that may be delivered by a wind generator, assuming that the wind kinetic energy is completely converted into mechanical energy. SOLUTION: Assume a rotor blade radius of r. ·The volume of air that moves through the blades in a time t is given by V = Ad = Avt, where v is the speed of the air and A = π r^2 ·The mass m is thus m = ρV = ρAvt · Kinetic energy = (1/2) mv^2 = (1/2) ρAvt v^2 = (1/2) ρ Av^3 t ·Power is Kinetic energy / time so that Power = ½ (Aρv^3)

PRACTICE: Since the air is still moving after passing through the rotor area, obviously not all of the kinetic energy can be used. The maximum theoretical efficiency of a wind turbine is about 60%. Given a turbine having a blade length of 12 m, a wind speed of 15 ms-1 and an efficiency of 45%, find the power output. The density of air, ρ is 1.2 kg m^-3 SOLUTION: A = π r^2 = π (12^2) = 452 m^2 Power = (0.45)(1/2) Aρv^3 = (0.45)(1/2) (452) x 1.2 x 15^3 = 411885 W = 410 kW Image from [|burnanenergyjournal.com]

8.2 - Thermal energy transfer // ** Nature of science: ** // Simple and complex modelling: The kinetic theory of gases is a simple mathematical model that produces a good approximation of the behaviour of real gases. Scientists are also attempting to model the Earth’s climate, which is a far more complex system. Advances in data availability and the ability to include more processes in the models together with continued testing and scientific debate on the various models will improve the ability to predict climate change more accurately. (1.12)

// ** Understandings: ** // • Conduction, convection and thermal radiation • Black-body radiation • Albedo and emissivity • The solar constant • The greenhouse effect • Energy balance in the Earth surface–atmosphere system

// ** Applications and skills: ** // • Sketching and interpreting graphs showing the variation of intensity with wavelength for bodies emitting thermal radiation at different temperatures • Solving problems involving the Stefan–Boltzmann law and Wien’s displacement law • Describing the effects of the Earth’s atmosphere on the mean surface temperature • Solving problems involving albedo, emissivity, solar constant and the Earth’s average temperature

//** International-mindedness: **// • The concern over the possible impact of climate change has resulted in an abundance of international press coverage, many political discussions within and between nations, and the consideration of people, corporations, and the environment when deciding on future plans for our planet. IB graduates should be aware of the science behind many of these scenarios.

• The debate about global warming illustrates the difficulties that arise when scientists cannot always agree on the interpretation of the data, especially as the solution would involve large-scale action through international government cooperation. When scientists disagree, how do we decide between competing theories?
 * // Theory of knowledge: //**

// ** Guidance: ** // • Discussion of conduction and convection will be qualitative only • Discussion of conduction is limited to intermolecular and electron collisions • Discussion of convection is limited to simple gas or liquid transfer via density differences • The absorption of infrared radiation by greenhouse gases should be described in terms of the molecular energy levels and the subsequent emission of radiation in all directions • The greenhouse gases to be considered are CH 4, H 2 O, CO 2 and N 2 O. It is sufficient for students to know that each has both natural and man-made origins. • Earth's albedo varies daily and is dependent on season (cloud formations)and latitude. The global annual mean albedo will be taken to be 0.3 (30%)for Earth.

• P = e σ AT 4 • <span style="font-family: 'Segoe UI Symbol',sans-serif;">λ max (metres) = 2.90 x10 -3 (m K) / T(kelvin) • I = power / A • albedo = total scattered power / total incident powerl
 * // Data booklet reference- //**

• Climate models and the variation in detail/processes included • Environmental chemistry (see Chemistry option topic C) • Climate change (see Biology sub-topic 4.4 and Environmental systems and societies topics 5 and 6) • The normal distribution curve is explored in Mathematical studies SL sub-topic 4.1
 * // Utilization: //**

• Aim 4: this topic gives students the opportunity to understand the wide range of scientific analysis behind climate change issues • Aim 6: simulations of energy exchange in the Earth surface–atmosphere system • Aim 8: while science has the ability to analyse and possibly help solve climate change issues, students should be aware of the impact of science on the initiation of conditions that allowed climate change due to human contributions to occur. Students should also be aware of the way science can be used to promote the interests of one side of the debate on climate change (or, conversely, to hinder debate).
 * // Aims: //**

Blackbody
Power emitted by an object is proportional to the surface area and the fourth power of the temperature. Black body radiation from [|sci.esa.in]t and [|www.giangrandi.ch] Task on Black body temperature simulation media type="custom" key="29290143" Black body simulation from [|phet.colorado.edu] The thermal energy ratiated by a blackbody emitter per second per unit area is proportional to the fourth power of the absolute temperature. Power/A = σ T 4 σ = 5.67 x 10^-8 W m^-2 K^-4 A is surface area ( A= 4PI r2) T is temperature in Kelvin
 * 1) <span style="font-family: 'open sans',helvetica,sans-serif; font-size: 14px; vertical-align: baseline; vertical-align: baseline;">Using the temperature slider, set the temperature to 3000 K (light bulb), 5700 K (Sun), and 8490 K (hot star).
 * 2) <span style="font-family: 'open sans',helvetica,sans-serif; font-size: 14px; vertical-align: baseline; vertical-align: baseline;">Use the zoom in and zoom out controls on the left side to adjust the y-axis as necessary.
 * 3) <span style="font-family: 'open sans',helvetica,sans-serif; font-size: 14px; vertical-align: baseline; vertical-align: baseline;">Compare the color of the object (the star-shaped object near the B G R color spots), the wavelength where the curve peaks, and the height of the curve's peak for all three temperatures.
 * Stefan- Boltzmann law **

The Stefan-Boltzmann law shows the relationship between the temperature of a black-body and the power emitted by the black-body’s surface area. A black-body emits as much power as it absorbs. Since no body is at absolute zero (K = 0) it follows from the Stefan-Boltzmann law that all bodies radiate. (Be sure that T is in Kelvin, not Celsius.)

For hot objects, the law is expressed in the form: Power/A = e σ T 4 e = P BODY / P BLACK-BODY e = P BODY / [ <span style="font-family: 'Segoe UI Symbol',sans-serif;">σ AT 4 ] and thus Power BODY = eσ AT 4 If the hot object is ratiating energy to its cooler surroundings at temperature T c the net radiation loss rate is Power = eσ A ( T 4 - T c 4 )
 * Emissivity **
 * <span style="display: inline !important;">The emissivity(e) of a body is a number between 0 and 1 that quantifies the emission and absorption properties of that body as compared to a blackbody of equal size.
 * A black-body is a perfect emitter / absorber of radiation ( an emissivity of e = 1 for ideal radidator)
 * A body that can’t emit / absorb radiation at all has an emissivity of e = 0.
 * The emissivity of a body is the ratio of the power emitted by the body, to the power emitted by a black-body of the same size.

λ max = 2.898 (mm K)/ T EXAMPLE 8: 1) Sun: 5800 K>> λ max = 500nm 2) Human: 310 K >> <span style="font-family: 'Segoe UI Symbol',sans-serif;">λ max = 9.35 micro m <span style="font-family: 'Segoe UI Symbol',sans-serif;">3) Molten iron 1810 K >>λ max <span style="font-family: 'Segoe UI Symbol',sans-serif;">= 1600nm <span style="font-family: 'Segoe UI Symbol',sans-serif;">4) Cosmic Background Radiation: 2725K >> λ max = <span style="color: #333333; font-family: q_serif,Georgia,Times,'Times New Roman',serif; font-size: 14px;"><span class="qlink_container"> Planck Law -- Wolfram Diagram from scienceworld.wolfram.com
 * Wien's displacement law ** indicates the wavelength of the maximum intensity lmax for black bodies at temperature T in Kelvin:

The power per unit area that is received by the object. It's average value is about 1400 W/m^2
 * Intensity **

I = POWER/Area I is intensity of light at a distance r from the point source A is cross-section area

The amount of power that arrives from the Sun is measured by solar constant. The unit is W/m^2 Ultraviolet, visible and infra red radiation are the three main types of radiation reaching the Earth's surface as atmosphere filters out many wavelengths.
 * The solar constant **

PRACTICE: The sun radiates energy at a rate of 3.90 X 10^26W. What is the rate at which energy from the sun reaches earth if our orbital radius is 1.5 X 10^11m? SOLUTION: I = P/ [4πr^2] = 3.90 x 10^26 / [4π(1.5 x 10^11)^2] · The surface area of a sphere is A = 4πr^2 · Intensity is the rate at which energy is being gained per unit area. Thus I = 1380 Wm^-2 (This is 1380 J/s per m^2) PRACTICE: The sun radiates energy at a rate of 3.90 x 10^26 W. What is the rate at which energy from the sun reaches Earth if our orbital radius is 1.5 x 10^11 m? SOLUTION: Area of sphere = 4(pi)r2. Intensity is the rate at which energy is being gained per unit area. Then I = P / [ 4(pi)r2 ] = 3.90 x 10^26 / [ 4pi(1.5 x 10^11)^2 ] = 1380 Wm^-2. This value is called the solar constant: Psun = 1380 W m^-2
 * Intensity = Power / A**

PRACTICE: The sun radiates energy at a rate of 3.90 x 10^26W. What is the rate at which energy from the sun reaches Jupiter if its orbital radius is 7.8 x10^11m? (This is Jupiter’s solar constant.) SOLUTION: Use I = P / [ 4pi r2 ] I = P / [ 4(pi)r^2 ] = 3.90 x 10^26 / [ 4pi(7.8 x 10^11)^2 ] I = 51 Wm^-2 This is 51 J / s per m^2

PRACTICE: a) Use data below to show that the power radiated by the Sun is about to be 4 x 10^26 W (Earth-Sun distance: 1.5 x 10^11 m, radius of Earth: 6.4 x 10^6 m, radius of Sun: 7.0 x 10^8, surface temperature of Sun: 5800 K) b) Calculate the solar power incident per unit area at a distance from the Sun equal to the Earth's distance from the Sun. SOLUTION: a) Power = σ A T 4 = 5.6 x 10^-8 x 4 Pi (7.0 x 10^8)^2 x (5800)^4 = 4.0 x 10^26 W b) I = P/A = 4.0 x 10^26 / 4 Pi ( 1.5 x 10^11)^2 = 1400 W/m^2

PRACTICE: From above a) and b), it is shown that the average power absorbed per unit area at the Earth's surface is 240 W/m^2 State reasons why the value of the solar power incident per unit area on Earth differs from the power radiated by the Sun at a distance on Earth. SOLUTION: The Earth's atmosphere and weather reflect some of the power. Only half the Earth's surface faces the Sun at any given time.

PRACTICE: Show that the value for power absorbed per unit area of 240 W/m^2 is consistent with an average equilibrium temperature for the Earth of about 255 K. SOLUTION: I = P / A = = σ A T 4 / A, P = = σ T 4, 240 W = 5.67 x 10^8 x (T)^4 T = 256 K

PRACTICE: Explain, by reference to the greenhouse effect, why the average temperature of the surface SOLUTION: Greenhouse gasses in the atmosphere absorbs the infrared radiation emitted by the Earth's surface and then reradiates it in random directions and back to the Earth. This causes the Earth's surface temperature to be higher and the radiation that escapes the atmosphere has a power of 240 W/m^2

The proportion of power reflected compared to the total power received. it is the ability of a planet to reeflect radiation.
 * Albedo **

albedo = total scattered power / total incident power Landforms, vegetation, weather, and seasons affect a planet’s albedo. Different terrains have different albedos. The Earth's albedo varies significantly depending on season, colours and susrface. Ocean water scatters little light (Albedo less than 0.1-low albedo). Snow(being white and shiny) and ice scatter a lot of light (Albedo more than 0.60- high albedo). The mirror has an albedo of almost 1. The black-body has an albedo of almost 0. The actual albedo depends on season, latitude, cloud cover, and snow cover. It varies daily.

Albedo = total scattered power / total incident power = I out / I in PRACTICE: It has been estimated that doubling the amount of carbon dioxide in the Earth's atmosphere changes the albedo of the Earth by 0.01. Use the data to show that this doubling will lead to a change of about 3 W/m^2 in the intensity being reflected by the Earth into space. (Average intensity received at Earth from the Sun = 340 W/m^2, Average albedo =0.3) SOLUTION: ΔP : Change in power, Po : Original power ΔP = Po(0.30 + 0.01) - Po(0.30) = 0.01 x Po = 0.01 x 340 = 3.4 W/m^2

Cs: surface heat capacity Cs = Q/(A x ΔT) ΔT = ( I in - I out )Δt / Cs <span style="background-color: #ffffff; color: #333333; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 14px; vertical-align: baseline;">media type="youtube" key="7Z-bMvBddIE" width="560" height="315" Before The Flood 2016, Climate Change Movie By Leonardo DiCaprio [|Living Green Life] <span style="display: block; font-family: Roboto,Arial,sans-serif; font-size: 10px;"> Published on 5 Nov 2016 =Essay (2000 words) Introduction: 23rd March= The concern over the possible impact of climate change has resulted in an abundance of international press coverage, many political discussions within and between nations, and the consideration of people, corporations, and the environment when deciding on future plans for our planet. Your assessed task for this sub-topic will be to write an essay about your selected energy source in your chosen area (Highly recommend to choose a local area in Vietnam). In your essay, you must include understanding of : • Renewable and non-renewable energy sources • Describing the basic features of fossil fuel power stations, nuclear power stations, wind generators, pumped storage hydroelectric systems and solar power cells • Describing the differences between photovoltaic cells and solar heating panels • Solving problems relevant to energy transformations in the context of these generating systems • Energy balance in the Earth surface–atmosphere system • The use of nuclear energy inspires a range of emotional responses from scientists and society. • How can accurate scientific risk assessment be undertaken in emotionally charged areas? __ **//For and Against//** __

**//Use your knowledge and understanding of://**
• Albedo and emissivity • The solar constant • The greenhouse effect • Earth's albedo varies daily and is dependent on season (cloud formations)and latitude. The global annual mean albedo will be taken to be 0.3 (30%)for Earth. • The absorption of infrared radiation by greenhouse gases should be described in terms of the molecular energy levels and the subsequent emission of radiation in all directions • The greenhouse gases to be considered are CH 4, H 2 O, CO 2 and N 2 O. It is sufficient for students to know that each has both natural and man-made origins. • Conduction, convection and thermal radiation • Black-body radiation • Stefan-Boltzmann law and Wien's displacement law • Derivation of the wind generator equation is not required but an awareness of relevant assumptions and limitations is required Bibliography must be included in all research tasks. You must include your reflections of Topic 8 Aim(s) in your essay.
 * //You may want to apply your knowledge and understanding of:// **
 * Due: Monday 17th April 2017 **

In your project, you should... ● consult the online PowerPoint, notes and the assessment criteria so that your efforts are not wasted, ● define the important concepts in your own words, ● include pictures, diagrams and statistics whenever they are relevant and don't forget to cite sources, ● show formulae and explain the meaning of each symbol, ● demonstrate in detail the usage of each formula through legitimate sample problems of your own design, including detailed solutions, ● adhere to significant figures and show correct units,

<span style="background-image: url(">Which emits more carbon dioxide: volcanoes or human activities? Article from climate.gov <span style="background-color: #ffffff; color: #333333; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 14px; vertical-align: baseline;"><span style="color: #666666; display: block; font-family: Cabin,Arial,sans-serif; font-size: 1em; vertical-align: baseline;">Author: <span style="color: #003366; display: inline !important; font-family: inherit; font-size: inherit; text-decoration: none; vertical-align: baseline;">[|Michon Scott] <span style="color: #003366; font-family: inherit; font-size: inherit; text-decoration: none; vertical-align: baseline;">[|Rebecca Lindsey] June 15, 2016 [|Are Volcanoes or Humans Harder on the Atmosphere?] Article from scientific american.com //<span style="color: #999999; font-family: Benton,Helvetica,Arial,sans-serif; vertical-align: baseline;"> Lyn Topinka, courtesy U.S. Geological Survey // (in class) <span style="background-image: url(">[|Greenshack Dotinfo] Published on 15 Aug 2016 || Tucker vs. Bill Nye the Science Guy [|Fox News] <span style="display: block; font-family: Roboto,Arial,sans-serif; font-size: 10px;">Published on 27 Feb 2017 || Climate Change: Prof Brian Cox (scientist) takes on Senator Malcolm Roberts (politician) <span style="font-family: Roboto,Arial,sans-serif; font-size: 10px;">[|Scott Arthur] Published on 16 Aug 2016 || Why I don't care about 'Climate Change' | David Saddington | TEDxTeen <span style="font-family: Roboto,Arial,sans-serif; font-size: 10px; text-decoration: none;">[|TEDx Talks] <span style="display: block; font-family: Roboto,Arial,sans-serif; font-size: 10px;">Published on 28 Oct 2014 || 13 Misconceptions About Global Warming [|Veritasium] Published on 22 Sep 2014 || media type="youtube" key="EtW2rrLHs08" width="560" height="315" Climate Change 101 with Bill Nye <span style="background-image: url(">[|National Geographic] <span style="font-family: Roboto,Arial,sans-serif; font-size: 10px;"> Published on 2 Dec 2015 || media type="youtube" key="eiPIvH49X-E" width="560" height="315" Global Warming; 31,487 Scientists say NO to Alarm [|1000frolly] Published on 22 Jul 2014 || media type="youtube" key="-AwNKQqLESc" width="560" height="315" Global Warming Is A Hoax <span style="background-image: url(">[|Counter Arguments] Published on 11 Dec 2016 || What They Haven't Told You about Climate Change [|PragerU] Published on 27 Jul 2015 || media type="youtube" key="RHrFBOUl6-8" width="560" height="315" Teachers TV- Climate Change - The Causes || media type="youtube" key="I0leiwOx6w0" width="560" height="315" Is Global Warming FAKE ? (Neil Degrasse Tyson vs Bob Lutz) <span style="font-family: Roboto,Arial,sans-serif; font-size: 10px;"><span style="background-image: url(">[|Asimovsfuture] Published on 27 Mar 2012 || media type="youtube" key="ifrHogDujXw" width="560" height="315" Climate Change Explained <span style="background-image: url(">[|The Daily Conversation] Published on 2 Dec 2015 || IB DP PHYSICS <span style="background-image: url(">[|ENERGY POWER and CLIMATE CHANGE keywords] quizlet media type="youtube" key="mZsaaturR6E" width="560" height="315" Fusion Energy Explained – Future or Failure [|Kurzgesagt – In a Nutshell] Published on 10 Nov 2016 [|How close are we to nuclear fusion] from Forbes.com What is the range of photon energies of X ray in eV ([|Electron volts])? E = hf = h(c/ λ), 1 eV = 1.6 x 10 -19 J , Range of wavelengths in X ray is c///f// = λ : 10 -6 ~ 10 -13 m, Range of frequencies in X ray spectrum: 10 17 ~ 10 20 Hz, A few hundred eV~ keV
 * Lesson || Date || In calss tasks || Outside class tasks ||
 * 1 ||  ||   ||   ||
 * media type="youtube" key="LxEGHW6Lbu8" width="560" height="315" || media type="youtube" key="qN5L2q6hfWo" width="560" height="315" || media type="youtube" key="qVB-rpC2x3w" width="560" height="315" || media type="youtube" key="7vnzKPq390Q" width="560" height="315" ||
 * Professor Brian Cox explains climate science to denier Australian Senator Malcolm Roberts
 * <span style="background-color: #ffffff; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12px; text-align: left;"> What is the IPCC? from [|ipcc website]
 * IPCC [|Summary for Policemakers 2014]
 * IPCC Assessment report 2014
 * media type="youtube" key="OWXoRSIxyIU" width="560" height="315"
 * media type="youtube" key="RkdbSxyXftc" width="560" height="315"

Human stupidity: [|The Gates of Hell in Turkmenistan] [|Johnny Ward] Published on 15 Feb 2016