Student Textbook PDF - Electronics and Hardware - Class 9

13 104565/2022/DSE JOB ROLE: FIELD TECHNICIAN – OTHER HOME APPLIANCES STUDENT TEXTBOOK CLASS 9 Sector: ELECTRONICS AND HARDWARE...

13 104565/2022/DSE JOB ROLE: FIELD TECHNICIAN – OTHER HOME APPLIANCES STUDENT TEXTBOOK CLASS 9 Sector: ELECTRONICS AND HARDWARE 1  14 104565/2022/DSE Page number 2 to 7 for Foreword, Acknowledgment, Test Book Development committee etc.  15 104565/2022/DSE NAME OF CHAPTER PAGE NO. CHAPTER 1. BASICS OF ELECTRICAL AND ELECTRONICS............................9-56 CHAPTER 2. ELECTRICAL AND ELECTRONIC COMPONENTS......................57-93 CHAPTER 3. TOOLS AND EQUIPMENT........................................................ 94-118 CHAPTER 4. INSTALLING AN RO WATER PURIFIER.....................................119- 185 CHAPTER 5. REPAIR AND MAINTENANCE OF WATER PURIFIER...................186 - 225 CHAPTER 6. MAINTAIN HEALTH AND SAFETY.............................................226 - 243 8  16 104565/2022/DSE Chapter 1 BASICS OF ELECTRICAL AND ELECTRONICS 1.0 INTRODUCTION Electricity has an important place in modern society. In this age, we have almost all the appliances that work on electricity. Even the automobile industry has started an electric car which will run on electricity instead of fuel. When power supply in a city breaks down, hospitals, hostels, office buildings, schools, food storage plants, banks and shops etc. will stop working. In this chapter we will focus on current electricity that powers our electronic and electrical gadgets. Electricity makes no sound, does not have an odour, and cannot be seen. Learning the theory of electricity make us cautious about hazards associated with all electrical appliances. So it is very important to understand the concept of electricity for installation and troubleshooting electrical appliances. The electric elements include controlled and uncontrolled source of energy, resistors, capacitors, inductors, etc. The electric circuit should be designed in the correct way to perform a specific function. Analysis of electric circuits refers to computations required to determine the unknown quantities such as voltage, current and power associated with one or more elements in the circuit. To work in the area of electrical engineering, the person should have the basic knowledge of electric circuit analysis and laws. Many other systems, like mechanical, hydraulic, thermal, magnetic and power system are easy to analyse and model by a circuit. To learn how to analyse the models of these systems, first one needs to learn the techniques of circuit analysis. We shall discuss briefly some of the basic circuit elements and the laws that will help us to develop the background of subject. In this chapter, students will understand the basic concepts of electricity and electrical circuits. Students can apply their knowledge to design, build, and demonstrate their own circuits Fig.1.1: Natural lightening 1.1 ELECTRICITY Electricity is the set of physical phenomena associated with the presence and flow of electric charge. Electricity gives a wide variety of well-known effects, such as lightning, static electricity, electromagnetic induction and electrical current. In addition, electricity permits the creation and reception of 9  17 104565/2022/DSE electromagnetic radiation such as radio waves. Electrical energy can be easily transferred from one location to another with minimum loss. 1.1.1 Source of Electricity Energy is the driving force for the universe. Energy is a quantitative property of a system. Natural electricity is generated by thunder storm and lightning as shown in figure 1.2. Fig.1.2: Natural discharging of charge, Courtesy: https://goo.gl/em8G1g Fig.1.3: Transmission tower, Courtesy: https://goo.gl/f6kGNx 10  18 104565/2022/DSE 1.1.2 Energy Transformation There are many different forms of energy, such as thermal energy, hydel energy, solar energy, wind energy, nuclear energy, etc. According to law of conservation of energy, the energy can neither be created nor destroyed it can only change its form. One form of energy can be transferred to another form. Electrical energy can be generated by transforming several types of energies. Nuclear → Electrical Chemical → Electrical Hydel → Electrical Thermal → Electrical Solar → Electrical Wind → Electrical For example, figure 1.4(a) and 1.4(b) shows how electrical energy can be generated from hydel energy in hydel power plant. Fig.1.4 (a) and Fig.1.4 (b): Generation and transmission of electricity, Courtesy: https://goo.gl/Q5REKP 11  19 104565/2022/DSE Fig. 1.5: Distribution of electricity, Courtesy: https://goo.gl/DtoSYN 1.1.3 Energy Foundation To understand electricity, we need to know something about atoms. Everything in the universe solid, liquid, gases are made up of atoms. Every star, every tree, every animal and even the human body are made of atoms. Atoms are the building blocks of the universe. Atoms are so small that millions of them would fit on the head of a pin. Atoms: The centre of an atom is called the nucleus. Atoms consist of sub atomic particles – protons, electrons and neutrons. The protons and neutrons are very small, and electrons are much, much smaller. Protons carries positive (+) charge, electrons carries negative (-) charge, neutrons are neutral. The positive charge of the protons is equal to the negative charge of the electrons. Electrons move in its orbit around the nucleus. The positively charge protons attract negatively charge electrons and hence holding the atomic structure as shown in figure 1.6. Fig.1.6: Atomic structure, Courtesy: https://goo.gl/hP7FhD 12  20 104565/2022/DSE Charge: Electric charge is a basic property of electrons, protons and other subatomic particles. Opposite charges attract each other and same charges repel each other. This makes electrons and protons stick together to form atoms. One foundational unit of electrical measurement is coulomb, which is a measure of electric charge proportional to the number of electrons in an imbalanced state. It was discovered by Charles-Augustine de Coulomb. One coulomb of charge is equal to the charge on 6x1018 (6,250,000,000,000,000,000) electrons. The symbol for electric charge quantity is the capital letter "Q," while the symbol of coulomb is represented by the capital letter "C." Flow of charge inside a wire Inside conductor free electrons randomly moves from one point to another. Due to this random flow net electric charge of a conductor is zero. When an external power source is attached, net flow of electrons is in one direction. This movement of electrons results in a current. If there is a current of 1 ampere passing through a wire it theoretically means that 6x1018 electrons are moving from one point to another in 1 second as shown in figure 1.7. Fig.1.7: Flow of charges 1.1.4 Conductors and Insulators When electrons move among the atoms of matter, a current of electricity is created. As in case of piece of wire, the electrons are passed from atom to atom, creating an electrical current from one end to another. Conductors: The material in which the electrons are loosely held, can move very easily. These are called conductors. The metals like copper, aluminium or steel are good conductors of electricity. Insulators: The materials which hold their electrons very tightly, do not allow to move the electrons through them very well. These are called insulators. Rubber, plastic, cloth, glass and dry air are good insulators and have very high resistance. 13  21 104565/2022/DSE 1.1.5 Type of Electricity As we have seen that electricity is a natural phenomenon. Naturally electricity is generated through lightning. This electricity is static in nature. Electricity can be generated in power plants. It is dynamic in nature. Thus electricity can be classified as: 1. Static electricity 2. Dynamic or Current electricity 1. Static electricity: Materials are made of atoms. Atoms are electrically neutral because they contain equal numbers of positive and negative charges. Static electricity requires a separation of positive and negative charges. When electrons do not move from one point to another point electricity is called static electricity. Energy stored in electric cell or battery is an example of static electricity. 2. Dynamic or Current electricity: Current electricity flows through wires or other conductors and transmits energy to devices. Flow of electricity is only possible because flow of charged particles like electrons. When electrons are in motion, electricity is called as dynamic or current electricity. Dynamic electricity cannot be stored. To store it has to be converted to static electricity. Current flowing through electrical wire and electrical AC appliances are the examples of dynamic electricity. Assignment  Discuss the source of electricity. Discuss about renewable and non- renewable source of electricity.  Prepare a data sheet in which electricity generating capacity of the five hydel power generating station are mentioned.  List out the names of top five thermal power plants in India as per their electricity generating capacity. 1.2 ELECTRICAL QUANTITIES Current, voltage, and resistance are the three basic building blocks of electric and electronic circuit. These are called as electrical quantities. You cannot see it with the naked eye the energy flowing through a wire or the voltage of a battery. An electric circuit is formed when a conductive path is created to allow free electrons to move continuously. This continuous movement of free electrons through the conductors of a circuit is called a current, and it is often referred to in terms of "flow," just like the flow of a liquid through a hollow pipe. The force motivating electrons to "flow" in a circuit is called voltage. Voltage is a specific measure of potential energy that is relative between two points. 14  22 104565/2022/DSE Free electrons tend to move through conductors with some degree of friction, or opposition to motion. This opposition to motion is called resistance. The amount of current in a circuit depends on the amount of voltage available to motivate the electrons, and also the amount of resistance in the circuit to oppose electron flow. The standard units of measurement for electrical current, voltage, and resistance are given below: Quantity Symbol Unit of Measurement Current I ampere (A) Voltage V volt (V) Resistance R ohm (Ω) The "symbol" given for each quantity is the standard alphabetical letter used to represent that quantity in an algebraic equation. Each unit of measurement is named after a famous experimenter in electricity: The amp after the Frenchman Andre M. Ampere, the volt after the Italian Alessandro Volta, and the ohm after the German Georg Simon Ohm. 1.2.1 Voltage Voltage is the potential difference between two points. Voltage is also the amount of work required to move one coulomb charge from one point to another point. Mathematically it can be written as, V=W/Q where, ‗V‘ is the voltage, ‗W‘ is the work in joule, Alessandro Volta (1745–1827) ‗Q‘ is the charge in coulomb. In an electric circuit the battery is used as an electric potential. Battery is one of the sources of voltage in electric circuit. Inside a battery, chemical reactions provide the energy needed to flow electrons from negative to positive terminal. When voltage is applied in electric circuit, negatively charged particles are pulled towards higher voltages, while positively charged particles are pulled towards lower voltages. Therefore, the current in a wire or resistor always flows from higher voltage to lower voltage. A voltmeter can be used to measure the voltage (or potential difference) between two points in a system. Value of voltage is measured in volt or joules per coulomb. Symbolic representation of voltage is ‘V’ or ‘v’. 15  23 104565/2022/DSE Example: When one joule of work is done to move one coulomb charge from one point to other point the potential difference between two points is said to be one volt. Fig.1.8: Flow of electrons on application of DC supply, Courtesy: https://goo.gl/MtLkLK Fig.1.9 Diesel AC voltage generator, Courtesy: http://bit.ly/2OCXheq Fig.1.10 DC voltage source in truck, Courtesy: http://bit.ly/2MfJgSh 1.2.2 Current The flow of electric charge is called electric current. The electrons carry charge. The electrons flow from one place to another. The number of moving electrons generates more charge. The amount of current flowing from one place to another is determined the amount of charge flowing through it per unit time as shown in 16  24 104565/2022/DSE figure 1.11. Unit of current is ampere (A). Symbolic representation of current is „I‟. Mathematically it can be written as, I= Q/t Where, ‗I‘ is the current, ‗Q‘ is the amount of charge in coulombs ‗t‘ is the time in seconds Note: Coulombs is the unit of charge. André-Marie Ampère (1775–1836) Example: If 1 coulomb charge passes through a point in 1 second, it will represent the 1 ampere current. Conventionally, the direction of current is taken as opposite to the flow of electrons. Fig. 1.11: Flow of charge through a cross section ‘A’, Courtesy: https://goo.gl/SHj3PF Fig.1.12 Flow of electrons in the conductor, Courtesy: http://bit.ly/2vyfoth Classification of current Depending upon the movement of electrons in an electric circuit, current can be classified as: 1. Direct current (DC) 2. Alternating current (AC) 17  25 104565/2022/DSE Direct Current Direct current is unidirectional in nature that is movement of electrons takes place only in one direction. This means that current flow only in one direction. DC voltage source (like batteries and cells) produces direct current. Direct current is used in wall clock, remote control, vehicles, automobile, cell phone etc. Alternating Current Alternating current is bidirectional in nature that is movement of electrons takes place in two directions. This means that current flow in two directions. AC voltage source (like AC generator) produces alternating current. Hydel power plants, thermal power plants etc. are the examples of alternating voltage sources. Alternating current is used in ceiling fan, cooler, washing machine etc. In India, standard AC generating frequency (f) of alternating current is 50 hertz. Frequency can be defines as ―the number of cycles in one second‖. From point A to point B represents one cycle. Hertz (Hz) is the unit of frequency. Example: 50 Hz represents 50 cycles in 1 second. Fig. 1.13: Cycle of AC signal The main difference between in AC and DC current is the directionality in the flow of electrons. In alternating current (AC, also ac), the movement of electric charge periodically reverses direction. In direct current (DC, also dc), the flow of electric charge is only in one direction. The usual waveform of an AC power circuit is a sine wave. In certain applications, different waveforms are used, such as triangular or square waves. Audio and radio signals carried on electrical wires are also examples of alternating current. 1.2.3 Resistance We know that in conductor‘s materials, electrons are loosely held and can move very easily. In insulators, electrons are tightly bound to their atoms and they do not move very easily. A very high voltage is required to move the electrons in an insulating material. On the other hand very small voltage is required to move the electrons in any conductor. In conductors the resistance is low, while in insulators the resistance is high. 18  26 104565/2022/DSE Resistance resists the flow of electron and hence electric current in the circuit. Conceptually the resistance controls the flow of electric current. The resistance is represented by the symbol "R". The SI unit of electrical resistance is the ohm (Ω). 1.2.4 Electric Power Electric power is the rate at which electric energy is Georg Simon Ohm (1789 - 1854) transferred by an electric circuit. Electric power, is the rate of doing work, means “amount of work done in one second”. The power is represented by symbol P. The SI unit of power is the watt (W). Unit of power is watt (W), which is equal to one joule per second. It is named in honour of Scottish inventor James Watt (1736 - 1819). Electric horsepower (hp) is another unit of measurement of power. It is equal to 746 watts. It measures to be slightly higher than mechanical horsepower, which is 745.7 joules per second. The electric power in watts produced by an electric current I consisting of a charge of Q coulombs every t seconds passing through an electric potential (voltage) difference of V is P = Work done per unit time = QV/t = V x I Where, Q is electric charge in coulombs t is time in seconds I is electric current in amperes V is electric potential or voltage in volts James Watt (1736 - 1819) P=W/t or P=I2R Where, ‗W‘ is the work done in joules ‗t‘ is the time in seconds Power can also be defined in terms of current and voltage i.e. product of voltage and current results in power. Watt is a measure of energy flow. Since watt, is a very small unit of power, in actual practice we need a much larger unit, the kilowatt, which is equal to 1000 watts. Since, product of power and time gives electrical energy; therefore unit of electrical energy is watt hour or kilowatt hour. One watt hour of energy is consumed when 1 watt of Fi g.1.14:Domest i c Effi ci ency power is used for 1 hour. The commercial unit of Li ght i ng Pr ogr amme (DELP) 9 Wat t LED electric energy is kilowatt hour (kWh). Cour t esy:ht t p://bi t.l y/2OGPq wj 19  27 104565/2022/DSE 1kWh = 1000 watt x 3600 second = 3.6 x 106 watt second or 3.6 x 106 joule For example, the power of this LED is 9 watt. This 9 watt defines it will do 9 joules of work in 1 second. LEDs are more efficient than CFL. More to know: Government of India has launched National Programme for LED-based Home and Street Lighting in New Delhi for energy conservation by reducing energy consumption. Along with this programme, Government of India launched scheme for Light Emitting Diode (LED) bulb distribution under the Domestic Efficient Lighting Programme (DELP). Fi g.1.15 Assignment: A 100 watt electric bulb is lighted for 2 hours daily, and four 40 watts bulbs are lighted for 4 hours daily. Calculate the energy consumed (in kWh) in 30 days. 1.2.5 Power Factor In AC circuit, various components are connected as resistor, inductor, and capacitor. These components consume power. When voltage is applied to an inductor it opposes the change in current. The current built up more slowly than the voltage, lagging in time and phase. In this way it can be stated that current lags the voltage. In case of capacitor, voltage is directly proportional to charge on it, current must lead the voltage in time and phase to conduct charge on the plates and raise the voltage. When inductor or capacitor is involved in an AC circuit, the current and voltage do not peak at same time. The fraction of a period difference between the peaks are expressed in degrees is said to be phase difference. The phase difference is