Introduction
Electricity is all around us-powering technology like our cell phones, computers, lights, soldering irons, and air conditioners. It's tough to escape it in our modern world. Even when you try to escape electricity, it's still at work throughout nature, from the lightning in a thunderstorm to the synapses inside our body. But what exactly is electricity? The concept of electricity is both familiar and mysterious. We all know what electricity is, or at least have a rough idea, based on practical experience. In particular, consider these points.
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We are very familiar with the electricity that flows through wires. That electricity comes from power plants that burn coal, catch the wind, or harness nuclear reactions. It travels from the power plants to our houses in big cables hung high in the air or buried in the ground. Once it gets to our houses, it travels through wires through the walls until it gets to electrical outlets. From there, we plug in power cords to get the electricity into the electrical devices we depend on every day.
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We know that electricity isn’t free.
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We know that electricity can be stored in batteries. When the batteries die, all their electricity is gone.
Definition of WORK an ENERGY
Unit of Energy
https://en.wikipedia.org/wiki/Units_of_energy
Example :
If it requires a steady force of 150 Newton to pull a boat, how much work is required to pull a boat 8 meters?
Given: Force = 200 N Distance = 10 m Unknown: Work =? Known: work (W) = force x distance 1N-m = 1 J
Solution: Work(W) = 200 N x 10 m = 2000 N.m =
2000 Joules W = 2000 J
Energy Conversion
One of the fundamental laws of classical physics states that, under ordinary conditions, energy can be neither created nor destroyed. The energy in the universe exists in various forms, such as heat energy, wind energy, light energy, and electrical energy. When we say we “use” electrical energy, we do not mean that we have destroyed, or lost the energy. We just converted that electric energy into a more useful form of energy. For example, when an electric fan was operated, electrical energy was converted to wind energy and heat energy. Although the electrical energy was converted and no longer exists as it is, electrical energy still exists in the form of wind and heat energy.
Efficiency
It is said that not all electrical energy that is put into a device or system is converted into the form of energy we desire since no conversion process is 100% efficient. For example, when 1000 joules of electric energy are put into an incandescent light bulb, only about 200 joules of light energy is produced while 800 joules are converted into heat energy. Having this situation, we could assume that the efficiency of an incandescent lamp is low.
Structure of Matter
All matter is composed of atoms. These are the basic building blocks of nature. Regardless of matter’s physical characteristics, glass, chalk, rock, and wood are all made from atoms. The smallest particle of substances that still has all of its characteristics is called a molecule. A molecule consists of two or more atom. If a molecule of chalk is divided into smaller parts, it is no longer a chalk. Matter composed of a single type of atom is called an element. Thus, there are as many elements as these are types of atoms. Some common elements are gold, silver, and copper.
Electric Charge
Both electrons and protons possess electric charges, but these charges are of opposite polarity. Polarity refers to the type (negative or positive) of charge
Task
At the end of the lesson, students are expected to answer different problem relates to work and energy.
They are expected to make there own web quest about their field of expertise.
Process
This curriculum unit is designed to teach a few basic concepts of electricity to middle school students. The teaching methods will include experimentation, demonstrations, analogies, discussion, work sheets and vocabulary review. Supplementary materials such as handouts and vocabulary cards will be presented in the unit. It is believed that all modalities should be used as often as possible in order to enable the students to understand the concepts and to be able to associate the concepts with the appropriate vocabulary. Too often a child does understand a concept but cannot demonstrate that he understands because he doesn’t know the correct words to express that the material has indeed been learned. The only source of electricity that will be used in experiments and demonstrations is a pair of 1.5 volt batteries. No matter what other references for experiments are used, batteries should be the only energy supply used by middle school, and possibly older and more experienced, students. The instructor must regularly remind the students that large voltages can be shocking and too often fatal.
Once a lesson is taught, the pertinent vocabulary should be retaught numerous times through the use of flash cards. Most lessons will introduce no more than three new words and their associated concepts. Each new word or term should be written on one side of a piece of construction paper and the definition should be written on the back. The students should be able to provide the term when the definition is shown and the definition when the word or term is shown. It is suggested that the students become thoroughly familiar with the key words and terms through the following use of the flash cards:
1) The teacher or student helper shows one side;
- 2) the class reads the words aloud
- 3) and then, the class as a group, reads the second side aloud
- 4) Individual students should be called on when they feel that they are ready to recite the opposite side of each term and definition.
5) All vocabulary cards should be reviewed at the beginning of each new lesson in this unit. Although this memorizing technique may seem too elementary to some teachers, students enjoy the method and take pride in being able to quickly associate the appropriate vocabulary word with a concept that they have just learned.
Evaluation
The following descriptions of progression in the development of conceptual understandings will help you to recognise students' conceptual development and then focus on ways to challenge them to achieve at higher levels.
Student understandings
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Students understand:
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