Lesson Plan and Lesson note on Conservation Principles
Energy and Society
Subject: Physics
Theme: Conservation Principles
Topic: Energy and Society
Sub Topic: Sources of energy
Date: dd/mm/yyyy
Class: S.S 3
Average Age: 16 years and above
Duration: 40 Minutes
No of Learners: 40
At the end of the lesson, the students should be able to:
1. Explain the term energy as used in this content
In the human society, the term energy is used as or the same with energy resources. It is most often refers to substances like fuel, petroleum products, electricity. For this lesson, we shall discuss energy as it is understood by human society and how it interacts and affects the society.2. List and Explain sources of energy
Sources of energy include the following:1. Petroleum and Natural gas (Fossil fuel)
2. Nuclear energy
3. Solar energy
4. Wind energy
5. Hydroelectric energy
6. Geothermal energy
7. Energy from coal and wood
8. Tidal and Ocean wave energy
9. Biomass energy
1. Petroleum and Natural gas (Fossil fuel)
Petroleum and natural gas are fossil fuels. A fossil is the remains of a plant or animal that has been buried in the earth (in rock, soil, ice, etc.) Fossil fuels were formed millions of years ago from the remains of plants and animals. The fossil fuels are petroleum, natural gas, and coal.(1) gas dissolved in the crude oil (solution gas),
(2) a distinct gas phase in contact with the crude oil (free gas), or
(3) both. Natural gas may also exist with no crude oil present (non-associated gas) in natural gas reservoirs. In the context just described, the terms “associated gas” and “non-associated gas” refer to the association of the gas with a liquid hydrocarbon phase.
Petroleum occurs naturally in two forms;
a. Liquid: Liquid petroleum occurs naturally in a reservoir or oil well and is called crude oil.
b. Gas: Gaseous petroleum is often referred to as Natural Gas.
Petroleum is a mixture of organic substance called Hydrocarbons. It is a valuable substance used as fuel and as raw material for the production of other products called PETROCHEMICALS.
Liquid petroleum or crude oil is further classified into light crude, which means the oil that can flow easily and heavy crude that implies the type of crude oil that does not flow easily. Bonny light is a type of crude oil produced in Nigeria.
Crude oil is refined in refineries to produce:
a) petrol
b) diesel
c) kerosene
d) lubricating oil, e.t.c.
These refined products are used for every mode of;
I transportation
II powering industrial machinery
III electricity generation
IV various domestic uses, e.g cooking, lighting of lamps, heating and cooling of houses and offices.
Nigeria is a petroleum producing country whose crude oil is highly valued by the world.
Advantages of using fossil fuels to generate electricity
(i) It is relatively cheap(ii) It is relatively easy to obtain because we have been using them for so long
(iii) It is reliable
Disadvantages of using fossil fuels to generate electricity
(i) they are non-renewable and will run out(ii) all fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming - coal produces most carbon dioxide and natural gas produces the least.
(iii) coal and oil release sulphur dioxide gas when they burn, which causes breathing problems for humans and animals and contributes to acid rain.
(iv) burning fossil fuels causes pollution as unburnt particles are released into the environment which can cause breathing difficulties and lung damage.
2. Nuclear energy
The use of nuclear power is for reducing world fuel shortages. It has the best prospect of providing the world enough of its energy needs, but fear of nuclear accidents always haunts the society for it can cause terrible disaster. Nuclear energy is environmental friendly as it does not pollute the atmosphere.Nuclear energy is a form of energy released from the nucleus, the core of atoms, made up of protons and neutrons. This source of energy can be produced in two ways:
Fission – when nuclei of atoms split into several parts or
Fusion – when nuclei fuse together.
Advantages of using nuclear fuel to generate electricity
(i) They do not produce carbon dioxide and so they do not contribute to global warming(ii) They do not produce sulfur dioxide and so they do not contribute to acid rain
(iii) They do not produce polluting gasses which contribute to smog
(iv) Requires lower quantity of fuel compared with fossil fuel power stations which reduces mining and transportation effects on environment
(v) They are reliable
Disadvantages of using nuclear fuel to generate electricity
(i) Like fossil fuels, nuclear fuels are non-renewable energy resources. They will run out one day if we keep on using them(ii) If there is an accident, large amounts of radioactive material could be released into the environment
(iii) Nuclear waste remains dangerously radioactive and harmful to health for thousands of years. It must be stored safely which has environmental implications
(iv) Costs of building and safely decommissioning a nuclear power station are very high
3. Solar energy
Solar energy is the energy available from the sun. It is a very useful form of clean energy. In sunny areas of the world, solar energy is collected by solar panel and concentrated on water to produce steam to drive turbine and for domestic heating purposes. It can also be converted to electricity for lighting our home and streets. It’s energy cannot be used up.Advantages of generating electricity using solar cells
(i) Solar energy is a renewable energy resource(ii) There are no fuel costs
(iii) No greenhouse gases are produced
(iv) No harmful polluting gases are produced
(v) Solar cells can provide electricity in remote locations where there is no mains electricity
(vi) Maintenance costs are low
Disadvantages of generating electricity using solar cells
(i) Solar cells are expensive and inefficient, so the cost of their electricity is high.(ii) Solar power is unreliable - solar cells do not work at night and not as well when it is cloudy
(iii) They use up a lot of space – some roofs are not big enough for the number of cells required
4. Wind energy
Wind energy results from uneven heating of the earth’s surface. It is driven by the thermal energy of the sun and can be used by sailing ships and for turning windmills. Wind energy resource is best generated along coastlines as well as on hills. Wind power can be used to produce largescale electricity that could be tied to the national electric networks. It is a clean form of energy.Advantages of generating electricity from wind
(i) Wind is a renewable energy resource(ii) There are no fuel costs
(iii) There are no harmful or polluting gases produced
Wind is one of the lowest-priced energy sources available today
(iv) Small-scale, stand alone, wind power is particularly suitable for remote locations where normal methods of electricity supply are expensive or hard to achieve
Disadvantages of generating electricity from wind
(i) Wind farms are noisy and may spoil the view for people living near them(ii) They are not reliable - the electricity generated depends on the strength of the wind - if there is no wind, there is no electricity
(iii) Wind farms can harm local wildlife - birds and bats have been killed by flying into spinning turbine blades and this can reduce local populations. This can be partially resolved by carefully siting wind plants
(iv) The initial cost of setting up wind turbines is quite high
5. Hydroelectric energy
The energy contained in the natural flow of water in rivers can be transformed into usable energy. Early uses included converting the energy to mechanical power for activities like milling and sawing, and for irrigation. Hydroelectric energy is a renewable source of energy from which electricity is produced by extracting energy from flowing and falling water using a hydraulic turbine and an electric generator.A conventional dam holds water in a man-made lake, or reservoir, behind it. When water is released through the dam, it spins a turbine connected to a generator that produces electricity.
Hydroelectric energy has been used to generate electricity for over a century and represents the world’s largest source of renewable electricity.
Advantages of generating electricity using waves, tides and hydroelectricity
(i) Waves, tides and hydroelectricity are forms of renewable energy resources.(ii) There are no fuel costs
(iii) No harmful polluting gases are produced.
(iv) Tidal barrages and hydroelectric power stations are very reliable and can be easily switched on. Hydroelectricity is particularly useful when there is a surge in demand for electricity.
(v) Hydroelectricity is low cost compared to coal and natural gas
Disadvantages of generating electricity using waves, tides and hydroelectricity
(i) It has been difficult to set up wave machines to produce large amounts of electricity.(ii) Tidal barrages destroy the habitats of estuary species, including wading birds and fish.
(iii) Tidal power is relatively new and so is quite expensive. (iv) Dams flood farmland and push people from their homes.
Large scale hydroelectricity projects can be particularly devastating for local environments. The Three Gorges Dam in China reportedly displaced more than 1.2 million people, flooding 13 cities, 140 towns, and 1,350 villages.
6. Geothermal energy
Geothrmal energy is the enormous energy or heat within the earth itself. Geothermal energy is generated wherever water comes in contact with hot rocks below the earth’s surface. The rocks give out heat that makes the water hot enough to turn into steam.Advantages of generating electricity from Geothermal
(i) Geothermal energy is a renewable energy resource.(ii) There are no fuel costs and no harmful polluting gases are produced.
(iii) The hot water and steam can be used to heat buildings directly.
Disadvantages of generating electricity from Geothermal
Most parts of the world do not have suitable areas where geothermal energy can be exploited.7. Energy from coal and wood
Energy from coal and wood is released when they are heated. The released energy is used in powering electric plants and driving some locomotives and for domestic uses. The use of coal and wood is not environmentally friendly as it pollutes the atmosphere.8. Tidal and Ocean wave energy
Tidal and ocean wave energy are due to the gravitational pull of the moon on water surrounding the earth. It is environmentally friendly. Ocean Wave energy refers to the harnessing of energy carried by ocean waves. Waves are created by the wind’s force on the surface of the ocean, and their characteristics determine the potential energy that can be extracted. Various technologies, such as wave energy converters, are used to capture and convert this energy into electricity.
Tidal energy, on the other hand, is generated by the movement of tides, which are caused by the gravitational pull of the moon and the sun. Devices like tidal turbines capture the kinetic energy of tidal currents and convert it into electricity.
The main difference between wave and tidal energy lies in their source. Wave energy is derived from the wind’s interaction with the ocean surface, while tidal energy is a result of gravitational forces. Additionally, the technologies used to harness each type of energy differ.
9. Biomass energy
Biomass energy is the energy released from the degradation or fermentation of organic materials like Cow dung, poultry waste, rice husk, weeds, human and animal excrements, garbage, cornstalks.Biomass energy is created by converting organic materials into usable energy through processes like combustion, gasification, and anaerobic digestion. These methods transform biomass into heat, electricity, biofuels, or biogas, making it a key player in the renewable energy mix.
(i) Combustion – Biomass materials such as wood or agricultural waste are burned to generate heat, which can directly heat buildings or produce steam to drive turbines for electricity. This is the simplest way to harness energy from biomass.
(ii) Gasification – Biomass is heated in a low-oxygen environment, creating a gas called syngas, which contains energy-rich hydrogen and carbon monoxide. Syngas is used for electricity, heat, or as a base for biofuel production.
(iii) Anaerobic Digestion – Organic materials, like food waste or manure, decompose in a controlled oxygen-free environment. This process produces biogas, primarily methane, which can be used for cooking, heating, or generating electricity
Types of Biomass Sources
(a) Plant-Based Biomass:
(i) Wood – Forestry waste like branches, sawdust, and wood chips is a primary biomass source for heat and electricity.
(i) Agricultural Residues – Leftovers from crops, such as straw, husks, and stalks, are used to generate energy efficiently.
(iii) Energy Crops – Specially grown plants, like switchgrass and miscanthus, are cultivated for bioenergy due to their high productivity and sustainability.
(iv) Algae – Fast-growing and rich in energy, algae are a promising feedstock for biofuels like biodiesel.
(b) Animal-Based Biomass:
(i) Manure – Livestock waste is used in anaerobic digestion to produce biogas, a renewable source of heat and power.
(ii) Waste-Derived Biomass
(a) Municipal Solid Waste (MSW) – Organic components of household and industrial waste, such as food scraps and paper, are processed for energy.
(b) Industrial Byproducts – Residues from food processing or sawmills are repurposed as bioenergy feedstocks.
Advantages of generating electricity from biomass
(i) Biomass is a renewable energy resource - humans and animals will always create waste and plants will always grow(ii) Using waste to create energy means that less of it goes into the landfill which is good for the environment
(iii) Burning biomass doesn’t release sulfur dioxide and it releases less nitrogen than burning coal
(iv) It’s a relatively cheap way to generate electricity
Disadvantages of generating electricity from biomass
(i) Crops grown in order to be burnt for energy take up a lot of land. That land could be used for other things like growing crops for food(ii) The burning process releases CO₂ which is a greenhouse gas
(iii) It also releases carbon monoxide, which adds to air pollution
(iv) When trees are cut down specifically to create energy there is a negative impact on the environment
3. Explain the term Renewable and Non-renewable energy resources
Renewable energy resources: are those that can be replaced as they are used up. E.g. solar energy, wind energy, water energy or hydroelectric power, biomass, tidal power, bio-fuels.Non-renewable energy resources: are those that cannot be replenished as they are used up. Examples are: Nuclear energy from radioactive materials, Petroleum and Natural gas, Coal and Wood, Such other fuel that are classified as fossil fuel.
4. List the uses/importance of energy
The use of energy has been a key in the development of the human society by helping it to control and adapt to the environment. In most countries, the development of energy resources has become essential in these vital areas of use such as:1. Agriculture (irrigation)
2. All forms of transportation, availability of petroleum products improves the transportation system.
3. Waste collection and recycling
4. Information technology
5. Communication
6. Electricity supply to homes and running industrial machinery
7. For heating or cooling of homes
8. Energy generation provides jobs and social amenities
8. For operating domestic equipment such as refrigerators, freezers, grinding machines, lighting our homes and streets etc. Many workers depend on electricity to carry out their businesses.
5. Explain the environmental impact of energy usage in the society
The use of energy resources has great effect on the environment. Burning of fossil fuel generates air pollutants including carbon dioxide, sulphur dioxide and nitrogen oxides etc. Burning fossil fuel for electricity generation also releases trace metals such as chromium, beryllium, cadmium, cooper. mercury, nickel, silver, etc into the environment. These act as pollutants. Carbon dioxide is an important green house gas, which is thought to be responsible for some fraction of the rapid increase in global warming seen especially in increasing temperature records observed all over the world including Nigeria.There are known global implications of the various forms of pollution being introduced into the atmosphere. These include:
(a) Acid Rain: This results when gaseous emissions of sulphur oxide, nitrogen oxide etc come into contact with water vapour and sunlight and are chemically convened to strong acidic compounds such as sulphuric acid, nitric acid etc, and are carried to the earth by rain drops, snow flakes, fog or dew. Environmental consequences of acid rain include considerable damage to building and monuments in highly industrialised areas and their environs. Acid rain also affects crops adversely and cause skin problems.
(b) Greenhouse Effect: is the trapping of the sun's radiation and heat in the lower atmosphere of the earth or any other planet caused by an increase in carbon dioxide which is rntirc transparent to solar radiation than to the reflected radiation from the earth. It is the process by which absorption and emission of infra-red radiation of the sun by such gases as carbon dioxide in the atmosphere. warm the eanh's lower atmosphere and surface. The problem of the greenhouse effect has led to increase of the earth's average temperature and this has led to increase in the melting of polar ice caps. This in turn is leading to increase in sea levels resulting in catastrophic flooding of the coastal areas.
(c) Global Warming: Global warming is simply the increase in the temperature of the earth's atmosphere caused when certain gases such as carbon dioxide, smokes, etc trap the sun's heat. Global warming is currently causing havoc and disruption on the earth's weather and climate. This increase is as a result of the increasing concentration of greenhouse gases such as carbon dioxide methane. etc which result from burning of fossil fuel and deforestation. An increase in global temperature will cause sea level to rise and will change the amount of and pattern of precipitation or rainfall and expansion of subtropical deserts, retreat of glaciers etc; also it could cause changes in the frequency and intensity of extreme weather events, and changes in agricultural yields. These events are already being observed around the world including Nigeria.
(d) Oil Spillage: This is a release of liquid petroleum hydrocarbon into the environment due to human activity and is a form of pollution. Oil spills include release of crude oil from tankers, offshore platform drilling rigs and oil wells as well as spills of refined petroleum products. e.g. Petrol. diesel and their by-products. and heavier fuels used by large ships. Oil spillage has destroyed bath human and aquatic lives and impairs birds flight abilities and kills off birds and fishes. Oil spillage also destroys farmland and pollutes rivers and streams. poisoning the drinking water of villages in the oil producing areas.
Explain the DEPLETION OF THE OZONE LAYER AND ITS EFFECTS
Ozone depletion is a gradual thinning of Earth’s ozone layer in the upper atmosphere caused by the release of chemical compounds containing gaseous chlorine or bromine from industry and other human activities.
An increase in ultraviolet radiation of relatively short wavelengths (UV-B rays is a radiation that is in the region of the ultraviolet spectrum which extends from about 280 to 320 nm in wavelength and that is primarily responsible for sunburn, aging of the skin, and the development of skin cancer) as a result of ozone layer depletion has many effects:1. causes a higher risk of skin cancer.
2. Plays a major role in malignant Melanoma development.
3. causes sunburn, quick aging, eye cataracts, blindness, and weakened immune system.
Explain the term energy crisis
An energy crisis is any great bottlenecks (e.g. price rise, shortage/scarcity, decisive moments) in the supply of energy resources to an economy. We are all familiar with sudden petrol scarcity or price hike in Nigeria and the attendant upheavals with light and struggles at the petrol station. Energy or energy resources are used to power or move vehicles, run industrial machinery, light tip our cities, operate gargets, and equipment in the homes etc. With increasing population growth and industrialisation, there has been an enormous demand on energy supply. Supply of energy is therefore far less than the actual demand.Energy crisis can occur due to shortage in supply or increasing demand, monopoly manipulation of market, industrial action by unions (e.g. strike by tanker drivers), bottlenecks at refineries and port facilities, vandalisation of pipelines, military coup, youth restiveness, political decisions, power outages, financial mismanagement of resources, political upheavals etc.
Rationale:
The idea of energy was used to explain the work output of steam engines and then generalised to understand other heat engines. It also became a key tool for understanding chemical reactions and biological systems. The world's energy resources include, fossil fuel (Petroleum, Natural gas), Solar energy, Nuclear energy, geothermal energy, wind energy, water energy, Biofuels, hydroelectricity. Renewable energy is energy resource that is replenishable. Non-renewable energy is energy resource that cannot be replenished or renewed after use or depletion. Environmentally friendly energy resources are those that do not pollute the environment. Examples are Solar Energy, Nuclear energy, Wind energy etc Hazardous energy resources include fossil fuels, petroleum, coal, wood etc. Energy resources are used for transportation, electricity supply, communication, Agriculture, information technology running industrial machinery, domestic use etc. The use of energy impacts on the environment through the greenhouse effect, global warming, depletion of the ozone layer, oil spillage, acid rain etc.Prerequisite/ Previous knowledge:
Photoelectric Effect.Learning Resources:
Flash cards, an audio and video youtube examples, Available useful objects.A chart showing showing various forms of energy
Reference Materials:
1. New system physics for secondary school by Dr. Charles chew etal2. New school physics by M. W Anyakoha
3. Internet
Lesson Development:
| STAGE | TEACHER'S ACTIVITY | LEARNER'S ACTIVITY | LEARNING POINTS |
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| STEP 1: INTRODUCTION Entire class |
The teacher asks the students the following question: 1. Explain the word energy? 2. List and explain various types/forms of energy. |
The students expected answers: 1. A body is said to possessing energy if it is capable of doing work. Various types of energy changed from one form to another as work was done by a system. The 'work done' by a system is the 'total energy transfer' by that system and is measured in Joules. That energy transfer is never totally transferred into 'useful output' and the efficiency of a system can be calculated by calculating the ratio of useful energy output to total energy input. efficiency = useful energy transferred ÷ total energy transferred.
Energy transfers can be useful (the energy being changed into a form we need). But whenever a transfer is made or energy is stored, some of the energy is 'dissipated'. That means it is 'lost to the surroundings' - shared out between air particles and particles of a container so that it cannot be made use of. 'Wasted energy' is the difference between total energy transfer and useful energy output. This is usually produced in the system in the form of heat. |
Identification of Prior Ideas and revising previous lesson |
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| STEP 2: Development and Grouping |
The teacher asks students to form groups and choose their leaders and secretaries. Thereafter, the teacher’s leads the students to understand that many substances burn. Some of them are used as fuels. Some fuels are burned in power stations to generate electricity, others a burned to provide heat or light for our homes. E.g. Oil, (Natural) gas, Coal are fossil fuels which are burned in power stations to generate electricity. Burning fuels can pollute the air E.g soot or carbon fragments, ash, smoke, sulphur dioxide (sulphur), carbon monoxide, carbon dioxide, oxides of nitrogen (nitrogen oxide), lead particles, acid rain, etc. Some power stations do not burn fuels. They use other energy resources to generate electricity. E.g, geothermal, wind, solar (Sun), running water accept (hydro or HEP or water power), waves, tidal, nuclear (uranium), etc. |
The students form groups and choose their leaders and secretaries. The students write down what the teacher explains and listen attentively. |
Inculcating leadership skills, competitive spirit, cooperation, teamwork and a sense of responsibility among learners. Developing the Concept of the topic Energy |
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| STEP 3: EXPERIMENTATION/ EXPLORATION Entire Class |
The teacher pass the pictures of energy sources, round the class for the students to observe. | The students observe the pictures. | sources of energy. |
| STEP 4: DISCUSSION Entire class |
Using the following question below, the teacher guides the students in discussing the activities. List sources of energy. |
The students Respond to the teachers question Sources of energy include the following: 1. Petroleum and natural gas (Fossil Fuel) 2. Nuclear energy 3. Solar energy 4. Wind energy 5. Hydroelectric energy 6. Geothermal energy 7. Energy from the coal wood 8. Tidal and Ocean 9. Biomass |
Sources of energy |
| Explain with examples Renewable and Non-Renewable Energy | Renewable Energy Resources are those that can be replaced as the used up. They can be continually replenished as the exploited and utilized. Examples are i. Solar energy ii. Wind energy iii. Biomass iv. Tidal Power v. Water or hydroelectric power vi. Biofuel Non-Renewable Energy Resources are those that cannot be replaced as the used up. They cannot be replenished as they are used up. Examples are i. Nuclear energy from radioactive material ii. Petroleum and Natural gas iii. Coal and wood iv. Such other fuel that are classified as fossil fuel. |
Renewable and Non-Renewable Energy | |
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| STEP 4: APPLICATION Entire class |
The teacher ask the students to list the Uses of Energy. Thereafter, the teacher ask the students to read through all they have copied and give more discussion/explanation as directed by the teacher. They take corrections where they are wrong. |
The students expected answers. In most countries, the development of energy resources has become essential in these vital areas of use such as: i. Agricultural- irrigation etc ii. All forms of transportation iii. Waste collection and recycling iv. Information technology v. Communication vi. Electricity supply to homes and running industrial machinery vii. For heating or cooling of homes. |
Better understanding of Energy. |
| STEP 5: EVALUATION Individual students |
The teacher asks the students questions to test them. 1. What is biomass? 2. Biomass and fossil fuels are both energy resources. What is the original source of this energy? Give the names of three fossil fuels which are often burned to generate electricity. 3. Fossil fuels are often described as non-renewable energy resources. Explain why they are called 'non-renewable'. 4. Give one advantage of using biomass rather than fossil fuel as an energy resource. 5. Give one advantage of using fossil fuel rather than biomass as an energy resource. 6. Give one disadvantage of using both fossil fuel and biomass. |
Students expected answers 1. Biomass is fuel material that comes from living things. It is primarily plant material. It is also waste matter from living animals or the dead form of them 2. The Sun's light is the original source of these energy forms. Both are formed into original material by photosynthesis, sunlight combining carbon dioxide and water into plant matter. Coal, oil and natural gas (or methane) are the three fossil fuels that are often burned to generate electricity. 3. Non-renewable resources cannot be naturally replaced in a small enough timescale for us to have an unlimited supply. When we have run out, it will take natural processes millions of years to form them again. 4. (a) it is renewable (b) it is widely available accept 'you can grow more of it' (c) it will conserve fossil fuel supplies 5. (a) it is a more concentrated fom of fuel energy- it contains more energy per unit mass (b) it is more suitable for use in vehicles (c) it can be transported more easily 6. (a) they release pollution into the atmosphere (b) they release greenhouse gases. |
Asking the learners questions to assess the achievement of the set objectives. |
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| CONCLUSION | The teacher concluded the lesson Properly managed biomass production maintains a balance of carbon dioxide in the atmosphere - as the CO2 it releases it took from the atmosphere when being grown. However, biomass 'farming' often operates on land that has been cleared of vegitation that originally would have retained more CO2 within the vegitation. It is not simple math to calculate the effect growing fuel crops has! |
The students write down the conclusion of the lesson and listen attentively. | Better understanding of Energy. |
| ASSIGNMENT | The teacher gives learners take home. 1. Coal is a non-renewable energy resource. Wood is a renewable energy resource. (a) Give two other non-renewable energy resources. [Ans. oil (petrol), natural gas (methane), nuclear (uranium)] (b) Why can wood be described as a renewable energy resource? [Ans. Wood is naturally replaced because more trees can be planted so that we can obtain more wood within a relatively short timespan.] (c) Give other renewable energy resources. [Ans. wind, wave, hydroelectric power, tidal, geothermal, solar (sunlight), biomass] (d) Complete the statement below to describe what happens when wood burns. When wood burns, chemical energy in the wood is transformed into .......... energy, which is transferred to the surroundings. [Ans. When wood burns, chemical energy in the wood is transformed into thermal or heat OR light energy, which is transferred to the surroundings] |
The learners copy the assignment | Better understanding of Energy. |