Basics Of Electricity PDF

BASICS OF ELECTRICITY HISTORY Nikola Tesla (1856–1943) pioneered the alternating current power system most of us use today. Even so, his rival, Thomas Edison (1846– 1931), is still popularly remembered as the inventor who gave the world electric power. Photograph by Sarony; engraving by T...

BASICS OF ELECTRICITY HISTORY Nikola Tesla (1856–1943) pioneered the alternating current power system most of us use today. Even so, his rival, Thomas Edison (1846– 1931), is still popularly remembered as the inventor who gave the world electric power. Photograph by Sarony; engraving by T. Johnson, c.1906, courtesy of US Library of Congress. 600 BCE: Greek philosopher Thales of Miletus (c.624–546 BCE) discovered static electricity. 1600 CE: English scientist William Gilbert (1544–1603) was the first person to use the word "electricity." He believed electricity was caused by a moving fluid called humor. 1733: French scientist Charles du Fay (1698–1739) found that there HISTORY 1752: American printer, journalist, scientist, and statesman Benjamin Franklin (1706– 1790) carried out further experiments and named the two kinds of electric charge "positive" and "negative." 1780: Italian biologist Luigi Galvani (1737–1798) touched two pieces of metal to a dead frog's leg and made it jump. This led him to believe electricity is made inside animals' bodies. 1785: French scientist Charles Augustin de Coulomb (1736–1806) explored the mysteries of electric fields: the electrically active areas around electric charges. 1800: One of Galvani's friends, an Italian physics professor named Alessandro Volta (1745–1827), realized "animal electricity" was made by the metals Galvani had used. After further research, he found out how to make electricity by joining different metals together and invented batteries. HISTORY 1827: German physicist Georg Ohm (1789–1854) found some materials carry electricity better than others and developed the idea of resistance. 1820: Danish physicist Hans Christian Oersted (1777–1851) put a compass near an electric cable and discovered that electricity can make magnetism. 1821: A French physicist called Andre-Marie Ampère (1775–1836) put two electric cables near to one another, wired them up to a power source, and watched them push one another apart. This showed electricity and magnetism can work together to make a force. 1821: Michael Faraday (1791–1867), an English chemist and physicist, developed the first, primitive electric motor. HISTORY 1830s: American physicist Joseph Henry (1797–1879) and British inventor William Sturgeon (1783–1850) independently made the first practical electromagnets and electric motors. 1831: Building on his earlier discoveries, Michael Faraday invented the electric generator. 1840: Scottish physicist James Prescott Joule (1818–1889) proved that electricity is a kind of energy. 1870s: Belgian engineer Zénobe Gramme (1826–1901) made the first large-scale electric generators. HISTORY 1873: James Clerk Maxwell (1831–1879), another British physicist, set out a detailed theory of electromagnetism (how electricity and magnetism work together). 1881: The world's first experimental electric power plant opened in Godalming, England. 1882: Thomas Edison (1846–1931) built the first large-scale electric power plants in the USA. 1890s: Edison's former employee Nikola Tesla (1856–1943) promoted alternating current (AC) electricity, a rival to the direct current (DC) system promoted by Edison. Edison and Tesla battled for supremacy and, although Edison is remembered as the pioneer of electric power, it was Tesla's AC system that ultimately triumphed.  WHAT IS ELECTRICITY? A form of energy that is carried through wires and is used to operate machines, lights. Electric current or power A fundamental form of energy observable in positive and negative forms that occurs naturally(as in lightning) or is produced(as in a generator) and that expressed in terms of the moment and interaction of electrons. Carries electrical energy and, as you have seen, electrical energy can change into other forms of energy. https://www.dummies.com/education/science/science-electr onics/electronics-basics-fundamentals-of-electricity/ ELECTRICAL CHARGE Fundamental property of matter that even physicists don’t totally understand. Suffice it to say that two of the tiny particles that make up atoms — protons and electrons — are the bearers of electric charge. There are two types of charge: positive and negative. Protons have positive charge, electrons have negative charge. TYPES OF ELECTRICAL POWER 1. Direct Current 2. Alternating Current DIRECT CURRENT Direct current - the unidirectional flow of electrical charge and substantially constant in value. is the type of electricity supplied by a battery. One terminal is positively charged, the other negatively charged, and electricity flows from one to the other, always in the same direction. However, while it is simple to make and control, DC does not travel well over long distances; it gets used up by the resistance in the transmission lines, and is gone before it gets to where it is needed. Alternating Current – an electric current that changes its direction very frequently at regular interval. ALTERNATING CURRENT also has a positive and a negative terminal, but the polarity and the direction of flow alternates many times per second. In the United States, electricity alternates polarity 120 times per second, or 60 full cycles per second, i.e. 60 Hz. AC can travel well over long distances, and so it the choice for power distribution lines. An electric current that changes its direction very frequently at regular interval. SIMPLE CIRCUIT The simplest circuit has a power source, like a battery or outlet, a wire running from the "hot" side to a "load", then a wire from the load back to the power source. There is also usually a switch to "open" or "close" the circuit. The load will function only when the circuit is closed or complete. HOW ELECTRICY FLOWS The electricity that flows to our homes is generated in power stations. From here, it flows through large transmission lines, which carry it to substations. Finally, distribution lines carry electricity from substations to houses, businesses, and schools like yours. Electricity flows easily through many materials and some of them make it much easier for it to flow through them than others. Most metals are not resistant to electric current and we call them “conductors.” The most common yet unobserved conductor is the surface of the earth. EFFECTS OF ELECTRICITY EFFECTS OF ELECTRIC SHOCK ON OUR BODY An electric shock is shocking in every sense of the word. It can result in a slight tingling sensation or in an immediate cardiac arrest. The severity ranges a lot and depends on the following factors: The amount of current that flows through your body The path of the current through the body The duration for which your body remains in the circuit The electric current’s frequency  ELECTRICAL BURNS - Heating due to the resistance of the body is the cause of electrical burns. If skin resistance is low, few, if any burns will occur. If skin resistance is high, energy may be dissipated at the surface resulting in large surface burns. NUEROLOGICAL EFFECTS - Electric current can interfere with the central nervous system, especially over the heart and lungs. Severe or repeated non-leathal shocks can damage nerves, which may impair sensation, movement, and gland or organ function. SKIN BREAKDOWN - The result is an increase in the amount of current that flows with any given voltage. Areas of skin breakdown are sometimes pinhead-sized wounds that can be easily overlooked. Effects of electrical current on the human body Current flowing through the heart causes fibrillation of the heart. Current flowing through muscles causes contraction of the muscles. Current flowing through the brain causes a loss of consciousness and seizers. In many cases, electric shock causes death. The threshold of perception for current entering the hand is about 5-10 mA for direct-current and about 1-5 mA for alternating-current at 60 hertz. Ventricular fibrillation occurs with currents as low as 60-100 mA in AC systems. For DC, about 300 to 500 mA. Static Electricity Electricity is a type of energy that can build up in one place or flow from one place to another. When electricity gathers in one place it is known as static electricity (the word static means something that does not move); electricity that moves from one place to another is called current electricity. Static electricity often happens when you rub things together. If you rub a balloon against your pullover 20 or 30 times, you'll find the balloon sticks to you. This happens because rubbing the balloon gives it an electric charge (a small amount of electricity). The charge makes it stick to your pullover like a magnet, because your pullover gains an opposite electric charge. So your pullover and the balloon attract one another like the opposite ends of two magnets. Static Electricity Lightning is also caused by static electricity. As rain clouds move through the sky, they rub against the air around them. This makes them build up a huge electric charge. Eventually, when the charge is big enough, it leaps to Earth as a bolt of lightning. You can often feel the tingling in the air when a storm is brewing nearby. This is the electricity in the air around you. Read more about this in our article on capacitors. Ohms Law - Current: The path an electric current follows - Unit for current is amp - An ammeter measures the amount of current flowing past a certain point Voltage (V) = Current (I) * Resistance (R) V = IR I=V/R R=V/I Voltage (V): This is the electrical potential difference between two points in a circuit. It is measured in volts (V). Current (I): This is the rate of flow of electric charge through a conductor. It is measured in amperes (A). Resistance (R): This is the opposition to the flow of electric current through a conductor. It is measured in ohms (Ω). Understanding Ohm’s Law Ohm’s law may be easier to understand with an analogy. Current flowing through a wire is like water flowing through a hose. Increasing voltage with a higher-volt battery increases the current. This is like opening the tap wider so more water flows through the hose. Increasing resistance reduces the current. This is like stepping on the hose so less water can flow through it. Increasing the resistance, decreases the flow of current… A series circuit is a circuit in which resistors are arranged in a chain, so the current has only one path to take. The current is the same through each resistor. You need to be aware of the following rules to work through the next questions. - Current in a series circuit is the same at all parts in a circuit. In a series circuit, the total, or sum of the voltages across all the components will equal the voltage across the cell/battery. - The total voltage supplied by the cell is 12V.