Fundamentals of Electronics and Electricity PDF

Fundamentals of Electronics and Electricity Nature of Electricity ⚫Electricity is made up of two opposing electric charges. These electric charges are the electrons and protons. The electrons are the basic negative charges, and the protons are the positive charges. Technically, movemen...

Fundamentals of Electronics and Electricity Nature of Electricity ⚫Electricity is made up of two opposing electric charges. These electric charges are the electrons and protons. The electrons are the basic negative charges, and the protons are the positive charges. Technically, movement of these opposing charges produces an electrical effect, which is known commonly as electricity. Kinds of electricity ⚫Static electricity- is also called electricity at rest, as energy, static electricity is called energy of position, or potential energy. ⚫Dynamic electricity-is also called electricity in motion. As energy, dynamic electricity can be called energy of motion or kinetic energy. An example of dynamic electricity is the electricity produced when we make the electric charges inside the batteries move to flow to perform useful work.  The electron theory ⚫Matter –in this context, is anything that has weight occupies space and made of molecules, and of which there are billions of different kind. ⚫all matters are made of electricity. ⚫Atom – the smallest particle of an element. Sub-atomic particles; ⚫Electrons-particle of an atom with negative charge ⚫Protons- particle of an atom with positive charge ⚫Neutrons- neutral in charge ⚫Nucleus- is the center of an atom ⚫ Valence electron-are the electron of contained in the valence shell of an atom, and which are likely to participate in a chemical action through bonding with other atoms or molecules. An electron of an atom, located in the outer most shell that can be shared with other atom. ⚫ Free electrons- electrons that cast away from its own shell, by means of attraction of by applying heat or light or by chemical reaction. Law of Charges ⚫Like charges repel each other, while unlike charges attract each other. From the attraction of this particles, the electron and protons, electricity started. This theory till now is the basis or concept regarding electricity and its property.  Structure of an Atom Example – Carbon Atom Nucleus 6 Protons - - 6 Neutrons Electrons + + ++ - + + - Orbits - - The distribution of electrons in the orbital rings around an atom’s nucleus determines the element’s electrical properties. 9 Conductor / Insulator / Semiconductor ⚫The stability of the electrons in the outer ring determines whether a material made from this element is a conductor, insulator, or semiconductor. ⚫Elements whose electrons are unstable and can easily move from one atom to another make good conductors. ⚫Elements whose electrons are stable and can not easily move from one atom to another make good insulators. ⚫Any elements that are not considered conductors or insulators are categorized as semiconductors. 10  Conductors ⚫ When an element’s outer electron ring is incomplete or not full, its electrons can move more freely from one atom to another atom. ⚫ Elements whose electrons can move more freely make good conductors. ⚫ In general, most metals make good conductors because they only have one or two electrons in their outer band. ⚫ Silver and gold are the best conductors. Copper is the second best conductor. Most wiring uses copper wire because it is a good conductor and is less expensive than the other metals. 11  Conductors: Example Ag & Cu Silver Copper (Ag) (Cu) Because the outer-most band is incomplete, the single electron is unstable and loosely bonded to the atom. Hence, it can easily 2 8 18 18 1 move to the outer band of 1 18 8 2 another adjacent atom. This free flow of electrons is what makes silver and copper good conductors. Number of 12 Nucleus Electrons in Orbit  Insulator ⚫ When an element’s outer ring is complete, or full, its electrons can not easily move from one atom to another atom. ⚫ Elements whose electrons can not move freely make good insulators. ⚫ Examples of good insulators are glass, plastic, rubber, paper, or air. Most wiring uses plastic as an insulator. ⚫ Plastics are polymers or long chains of atoms bonded to one another. Viewing the atomic structure of plastics is far beyond the scope of this class (If you are interested in such topics, you may want to take AP Chemistry.). ⚫ Neon and argon, both gases, are good insulators and 13 are often used in light bulbs. Insulator: Example Ne & Ar Neon Argon (Ne) (Ar) The outer-most orbits of neon and argon can each contain a maximum of eight (8) electrons. This is exactly how many they have. This makes 2 8 the electron in the outer-most bands 8 8 2 stable. This stable electron structure is what makes neon and argon good insulators. 14  Semiconductor ⚫When an element’s outer ring is neither complete nor incomplete, the element is considered to be a semiconductor. ⚫Examples of good semiconductor materials are ⚫Carbon (used to make resistors) ⚫Silicon (used to make transistors) 15 Semiconductors: Example C & Si Carbo Silicon n (Si) (C) The outer-most orbits of carbon and silicon can each contain a maximum of eight (8) electrons. Because they both contain four (4), 2 4 these electrons are neither stable 4 8 2 nor unstable. This electron structure is what makes carbon and silicon good semiconductors. 16 Voltage (V), Current (I), and Resistance (R) Voltage ⚫ Volts or voltage is the measure of push on each electron that makes the electron move. The term potential difference and voltage are often used interchangeably to means the “push”, thus, you may see the charge electromotive force (EMF) or just the word potential to describe the electron push in some instances. ⚫ When writing voltages in electrical formulas, the letter E is used to symbolized voltage or potential difference, while the letter V is commonly used to abbreviate the unit of voltage on volts. Voltage and Batteries ⚫ Batteries are voltage sources. ⚫ Batteries can be thought of as charge pumps. ⚫ They take a charge and though chemical reactions pump them up to a certain voltage, or potential energy level. ⚫ As the charge flows through the circuit, this potential energy can be used by the circuit to do work. The charge loses energy as it goes through the loads. ⚫ Heat up a filament ⚫ Make a motor turn. ⚫ Energy gained from the battery = energy lost by the loads.  Current ⚫Current is a flow of electrical charge carriers, usually electrons or electron- deficient atoms. The common symbol for current is the uppercase letter I. The standard unit is the ampere, symbolized by A. One ampere of current represents one coulomb of electrical charge (6.24 x 1018 charge carriers) moving past a specific point in one second. Alternating current & Direct current ⚫Alternating Current (AC) is a type of electrical current, in which the direction of the flow of electrons switches back and forth at regular intervals or cycles. Current flowing in power lines and normal household electricity that comes from a wall outlet is alternating current. The standard current used in the U.S. is 60 cycles per second (i.e. a frequency of 60 Hz); in Europe and most other parts of the world it is 50 cycles per second (i.e. a frequency of 50 Hz.). ⚫Direct current (DC) is electrical current which flows consistently in one direction. The current that flows in a flashlight or another appliance running on batteries is direct current. ⚫One advantage of alternating current is that it is relatively cheap to change the voltage of the current. Furthermore, the inevitable loss of energy that occurs when current is carried over long distances is far smaller with alternating current than with direct current.  Resistance ⚫ Resistance is the opposition that a substance offers to the flow of electric current. It is represented by the uppercase letter R. The standard unit of resistance is the ohm, sometimes written out as a word, and sometimes symbolized by the uppercase Greek letter omega: Ω ⚫ Resistance is lot like friction they both act to oppose motion and generate heat Factors that affects resistance There are several factors that affect the resistance of a conductor; material e.g. copper has lower resistance than steel length - longer wires have greater resistance thickness - smaller diameter wires have greater resistance temperature - heating a wire increases its resistance Circuits ⚫Consists of a voltage source, a load, and a path for current between the source and the load. ⚫A load is a device on which work is done by the current through it. ⚫Open circuits versus closed circuits.  Ground ⚫ A ground is a direct electrical connection to the earth, a connection to a particular point in an electrical or electronic circuit, or an indirect connection that operates as the result of capacitance between wireless equipment and the earth or a large mass of conductive material. ⚫ Electrical grounding is important because it provides a reference voltage level (called zero potential or ground potential) against which all other voltages in a system are established and measured. An effective electrical ground connection also minimizes the susceptibility of equipment to interference, reduces the risk of equipment damage due to lightning, eliminates electrostatic buildup that can damage system components, and helps protect personnel who service and repair electrical, electronic, and computer systems. In effect, an electrical ground drains away any unwanted buildup of electrical charge. When a point is connected to a good ground, that point tends to stay at a constant voltage, regardless of what happens elsewhere in the circuit or system. The earth, which forms the ultimate ground, has the ability to absorb or dissipate an unlimited amount of electrical charge Ohm’s law ⚫Ohm’s law is an electrical law that is used to determine the electrical power of the electric circuit. Ohm’s law was devised by Georg Simon Ohm, a German scientist. With ohm’s law we can analyze the amount of electric current resistance and applied voltage of the electrical circuit. The letter symbol that used in ohm’s law are: ⚫V (E or emf) – voltage ⚫I – intensity of the flowing electric current. ⚫R – Resistance or the opposition to the flow of electric current The relationship between current, voltage and resistance is explained algebraically, using this formula: E I R Ohm’s Law Formula: For Voltage E = IxR For Current I = E. R For Resistance R = E. I Ex. 1 Find the resistance of the given circuit diagram. II = 2A R R= = ?? Solution: Given: E=12 volts I= 2A R=? R= E. I R= 12volts/ 2A R=6 ohms Ex. 2 Find the voltage in the given circuit diagram I = 2A E=? R= 6 Ohms Solution: Given: I=2A R= 6 ohms E=? E=I X R E=2A x 6 ohms E= 12 volts