SECOND TERM E-LEARNING NOTE
SUBJECT: BASIC SCIENCE
CLASS: JSS 1
REFRENCE
- Precious Seed BASIC SCIENCE FOR JUNIOR SECONDARY SCHOOLS BOOK 1
WEEK NINE DATE …………….
TOPIC: ENERGY
Energy is the amount of force or power when applied can move one object from one position to another or Energy defines the capacity of a system to do work. Energy exists in everybody whether they are human beings or animals or non living things for e.g.: Jet, Light, Machines etc.
SOURCES OF ENERGY
- Solar Energy: Solar power harvests the energy of the sun through using collector panels to create conditions that can then be turned into a kind of power. Large solar panel fields are often used in desert to gather enough power to charge small substations, and many homes use solar systems to provide for hot water, cooling and supplement their electricity. The issue with solar is that while there is plentiful amounts of sun available, only certain geographical ranges of the world get enough of the direct power of the sun for long enough to generate usable power from this source.
- Wind Energy: Wind power is becoming more and more common. The new innovations that are allowing wind farms to appear are making them a more common sight. By using large turbines to take available wind as the power to turn, the turbine can then turn a generator to produce electricity. While this seemed like an ideal solution to many, the reality of the wind farms is starting to reveal an unforeseen ecological impact that may not make it an ideal choice.
- Geothermal Energy: Geothermal energy is the energy that is produced from beneath the earth. It is clean, sustainable and environment friendly. High temperatures are produced continuously inside the earth’s crust by the slow delay of radioactive particles. Hot rocks present below the earth heats up the water that produces steam. The steam is then captured that helps to move turbines. The rotating turbines then power the generators. Geothermal energy can be used by a residential unit or on a large scale by a industrial application. It was used during ancient times for bathing and space heating. The biggest disadvantage with geothermal energy is that it can only be produced at selected sites throughout the world. The largest group of geothermal power plants in the world is located at The Geysers, a geothermal field in California, United States.
- Hydrogen Energy: Hydrogen is available with water (H2O) and is most common element available on earth. Water contains two-thirds of hydrogen and can be found in combination with other elements. Once it is separated, it can be used as a fuel for generating electricity. Hydrogen is a tremendous source of energy and can be used as a source of fuel to power ships, vehicles, homes, industries and rockets. It is completely renewable, can be produced on demand and does not leave any toxic emissions in the atmosphere.
- Tidal Energy: Tidal energy uses rise and fall of tides to convert kinetic energy of incoming and outgoing tides into electrical energy. The generation of energy through tidal power is mostly prevalent in coastal areas. Huge investment and limited availability of sites are few of the drawbacks of tidal energy. When there is increased height of water levels in the ocean, tides are produced which rush back and forth in the ocean. Tidal energy is one of the renewable source of energy and produce large energy even when the tides are at low speed.
- Wave Energy: Wave energy is produced from the waves that are produced in the oceans. Wave energy is renewable, environment friendly and causes no harm to atmosphere. It can be harnessed along coastal regions of many countries and can help a country to reduce its dependence on foreign countries for fuel. Producing wave energy can damage marine ecosystem and can also be a source of disturbance to private and commercial vessels. It is highly dependent on wavelength and can also be a source of visual and noise pollution.
- Hydroelectric Energy: What many people are not aware of is that most of the cities and towns in the world rely on hydropower, and have for the past century. Every time you see a major damn, it is providing hydropower to an electrical station somewhere. The power of the water is used to turn generators to produce the electricity that is then used. The problems faced with hydropower right now have to do with the aging of the dams. Many of them need major restoration work to remain functional and safe, and that costs enormous sums of money. The drain on the world’s drinkable water supply is also causing issues as townships may wind up needing to consume the water that provides them power too.
- Biomass Energy: Biomass energy is produced from organic material and is commonly used throughout the world. Chlorophyll present in plants captures the sun’s energy by converting carbon dioxide from the air and water from the ground into carbohydrates through the process of photosynthesis. When the plants are burned, the water and carbon dioxide is again released back into the atmosphere. Biomass energy is used for heating and cooking in homes and as a fuel in industrial production.
- Nuclear Power: While nuclear power remains a great subject of debate as to how safe it is to use, and whether or not it is really energy efficient when you take into account the waste it produces – the fact is it remains one of the major renewable sources of energy available to the world. The energy is created through a specific nuclear reaction, which is then collected and used to power generators.
- Fossil Fuels (Coal, Oil and Natural Gas); Fossil fuels provide the power for most of the world, primarily using coal and oil. Oil is converted into many products, the most used of which is gasoline. Natural gas is starting to become more common, but is used mostly for heating applications. Although, there are more and more natural gas powered vehicles appearing on the streets.. The fossil fuel reserves are also limited, expecting to last only another 100 years given are basic rate of consumption.
Evaluation
- What is energy?
- State five sources of energy?
Different Forms of Energy
Energy exists in many different forms. Examples of these are: light energy, heat energy, mechanical energy, gravitational energy, electrical energy, sound energy, chemical energy, nuclear or atomic energy and so on. These forms of energy can be transferred and transformed between one another. This is of immense benefit to us. For a source of energy to end up as electricity it may undergo many transformations before it can power the light bulb in your home.
Although there are many specific types of energy, the two major forms are Kinetic Energy and Potential Energy.
Kinetic energy is the energy in moving objects or mass. Wind energy is an example. The molecules of gas within the air, are moving giving them kinetic energy.
Potential energy is any form of energy that has stored potential that can be put to future use. For example, water stored in a dam for hydroelectricity generation is a form of potential energy. When valves are opened the force of gravity cause water to begin to flow. The gravitational potential energy of the water is converting to kinetic energy. The flowing water can turn a turbine, which will further convert the kinetic energy of the water into useable mechanical energy. An alternator or generator then converts the mechanical energy from the turbine into electrical energy. This electricity is then sent to the electricity grid and to our homes where it is converted into light energy (lights and televisions), sound energy (televisions, stereos), heat energy (hot water, toasters, ovens), mechanical energy (fans, vacuum cleaners, fridge and air conditioner compressors) and so on.
ENERGY CONVERSION
We meet energy conversions many times every day of our lives. The following are types of energy conversion and their converters or converting devices.
ENERGY CONVERSION ENERGY CONVERTER
Chemical to heat energy Match, rockets
Electrical to sound energy Electric Bell, loudspeaker
Chemical to Electrical Dry Cells (Batteries)
Light to chemical energy Green plant leaves
Mechanical to mechanical Brakes of a car/bike
Chemical to mechanical Human body /car
Mechanical to sound energy Drum/hand bell
Chemical to sound energy Firework (Banger)
Sound to Electrical energy Microphone
EVALUATION
- State the law of conservation of energy.
- List five forms of energy
- List five examples of energy conversions and their converters in each case.
General Evaluation
- State the law of conservation of energy.
- List five forms of energy
- List five examples of energy conversions and their converters in each case.
- What is energy?
- What are five sources of energy?
READING ASSIGNMENT; Precious seed BASIC SCIENCE FOR JUNIOR SECONDARY SCHOOLS BOOK 1 PAGE 134-145
WEEKEND ASSIGNMENT
- The mainspring to all life activities is the A. energy B. power C. work D. force
- The device which can convert solar energy to electricity is the A. electro magnet B. photo voltaic solar panel C. turbine D. dynamic
- The chlorophyll in plants use -------- to produce energy. A. light B. plant C. sun
- atmosphere.
- The energy directly from the sun is converted using ------- A. voltaic solar panel
- generator C. photogenic machine D. none
- The law of conservation of energy is also known as -------- A. First law of thermodynamic B. law of mass action C. Pythagoras theorem D. Indosian theory.
Theory
- State the law of conservation of energy
- List five energy conversion and their converters
