EE-200 Learning Module 1: Introduction to Electricity PDF

Unit 1 Learning Module 1 INTRODUCTION TO ELECTRICITY INTENDED LEARNING OUTCOMES: After completing this unit, you are expected to: 1. identify the methods of electricity and effects of electricity 2. describe the different electrical components....

Unit 1 Learning Module 1 INTRODUCTION TO ELECTRICITY INTENDED LEARNING OUTCOMES: After completing this unit, you are expected to: 1. identify the methods of electricity and effects of electricity 2. describe the different electrical components. 3. Identify various electrical instruments. 4. Identify the fundamental electrical quantities and units. 5. use metric prefixes in simplifying large and small numbers. 6. perform mathematical operations involving powers of ten and metric prefixes. 7. explain the difference between direct current and alternating current. electricity semiconductor static electricity active element dynamic electricity passive element resistor electrical quantities resistance metric prefixes inductor direct current inductance alternating current transformer Definition of Electricity Electricity is a physical phenomenon arising from the existence and interaction of electric charge. It is a form of energy generated by friction, heat, light, magnetism, chemical reaction, and pressure.  Two Types of Electricity: Static electricity – electricity at rest. It cannot flow from one place to another. Dynamic electricity – also known as current electricity. Electricity in motion. It can be transmitted from one place to the other.  Methods of Producing Electricity There are six methods for producing electricity: 1.Magnetism 2.Chemical reaction 3.Pressure 4.Heat 5.Friction 6.Light A piezoelectric disk generates a voltage when deformed (change in shape is greatly exaggerated) https://www.quora.com/What-is-the-working-principle-of-a-solar-cell Electrical Effects With the exception of friction, electricity can be used to cause the same effects that cause it. 1.Magnetism 2.Chemical action 3.Pressure 4.Heat 5.Light  Methods of Effects of Producing Electricity Electricity ▪ Magnetism ❖ Magnetism ▪ Chemical ❖ Chemical reaction ❑ Generator reaction ▪ Pressure ❑ Solar Cell ❖ Pressure ▪ Heat ❑ Battery ❖ Heat ▪ Friction ❖ Light ▪ Light A B C EXAMPLE What effects of electricity are evident in a light bulb? A. light B. heat C. heat and light D. magnetism Circuit Components Resistors These can be the carbon-composition type or wound with special resistance wire. Their function is to limit the amount of current or divide the voltage in a circuit. Capacitors A capacitor is constructed of two conductor plates separated by an insulator (called a dielectric). Its basic function is to concentrate the electric field of voltage across the dielectric. As a result, the capacitor can accumulate and store electric charge from the voltage source. The practical application is effect is the use of capacitors to pass an ac signal but to block a steady dc voltage. Inductors An inductor is just a coil of wire. Its basic function is to concentrate the magnetic field of electric current in the coil. Most important, an induced voltage is generated when the current with its associated magnetic field changes in value or direction. Inductors are often called chokes. In the practical application of a choke, the inductor can pass a steady current better than alternating current. Transformers Transformers are most commonly used for increasing low AC voltages at high current (a step-up transformer) or decreasing high AC voltages at low current (a step- down transformer) in electric power applications, and for coupling the stages of signal processing circuits. Semiconductor Devices Semiconductors are substances with properties somewhere between them conductors and insulators. ICs(integrated circuits) and electronic discrete components such as diodes and transistors are made of semiconductors. Common elemental semiconductors are silicon and germanium. Silicon is well-known of these. Silicon forms most of ICs. Common semiconductor compounds are such as gallium arsenide or indium antimonide.  Active and Passive Elements Active elements - are capable of delivering power to some external device. Examples: dependent and independent voltage and current sources Passive elements – are capable of receiving power. They are able to store to store finite amounts of energy and then return that energy later to various external devices. Examples are resistors, inductors, and capacitors. Measuring Instruments Electrical Quantities and Units with SI Symbols Quantity Symbol Unit Symbol Capacitance C farad F Charge Q coulomb C Conductance G siemen S Current I ampere A Energy W joule J Frequency f hertz Hz Impedance Z ohm  Inductance L henry H Power P watt W Reactance X ohm   Commonly Used Metric Prefixes in Electricity Power of Value Metric Prefix Metric Symbol Ten 109 one billion giga G 106 one million mega M 103 one thousand kilo k 10-3 one-thousandth milli m 10-6 one-millionth micro  10-9 one-billionth nano n 10-12 one-trillionth pico p Scientific Notation Scientific notation is the way that scientists easily handle very large numbers or very small numbers. For example, instead of writing 0.0000000056, we write 5.6 x 10-9. So, how does this work? We can think of 5.6 x 10-9 as the product of two numbers: 5.6 (the digit term) and 10-9 (the exponential term). Here are some examples of scientific notation. 10000 = 1 x 104 24327 = 2.4327 x 104 1000 = 1 x 103 7354 = 7.354 x 103 100 = 1 x 102 482 = 4.82 x 102 89 = 8.9 x 101 (not usually 10 = 1 x 101 done) 1 = 100 0.32 = 3.2 x 10-1 (not usually 1/10 = 0.1 = 1 x 10-1 done) 1/100 = 0.01 = 1 x 10-2 0.053 = 5.3 x 10-2 1/1000 = 0.001 = 1 x 10-3 0.0078 = 7.8 x 10-3 1/10000 = 0.0001 = 1 x 10-4 0.00044 = 4.4 x 10-4 As you can see, the exponent of 10 is the number of places the decimal point must be shifted to give the number in long form. A positive exponent shows that the decimal point is shifted that number of places to the right. Example: 24327 = 2.4327 x 104 A negative exponent shows that the decimal point is shifted that number of places to the left. Example: 0.0078 = 7.8 x 10-3 In scientific notation, the digit term indicates the number of significant figures in the number. The exponential term only places the decimal point. As an example, 46600000 = 4.66 x 107 This number only has 3 significant figures. The zeros are not significant; they are only holding a place. As another example, 0.00053 = 5.3 x 10-4 This number has 2 significant figures. The zeros are only place holders. EXAMPLE Express the following as a quantity having a metric prefix: 1) 89 x 10-9 F = 89 nF 2) 270 x 10-6 A = 270 µA 3) 385 x 103 V = 385 kV 4) 375 x 103 x 103 V = 375 MV EXAMPLE 1)What is 62000000000 Ω in GΩ? Solution: 62000000000 Ω = 62000000000 x 10 0 Ω Moving 9 decimal places to the left, 62000000000 x 100 becomes 62 x 100+9 (add 9 to the exponent) So, 62000000000 Ω = 62 x 100+9 Ω = 62 x 109 GΩ = 62 GΩ 2) What is 0.00000000543 F in nF? Solution: 0.00000000543 F = 0.00000000543 x 100 F Moving 9 decimal places to the right, 0.00000000543 x 100 becomes 5.43 x 100-9 (subtract 9 to the exponent) So, 0.00000000543 F = 5.43 x 100-9 Ω = 5.43 x 10-9 F = 5.43 nF 3) Convert 10000 kV to MV. Solution: 10000 kV = 10000 x 103 V Moving 3 decimal places to the left, 10000 x 103 becomes 10 x 103+3 (add 3 to the exponent) So, 10000 kV = 10 x 10 3+3 V = 10 x 106 V = 10 MV 4) Convert 45000 µA to mA. Solution: 45000 µA = 45000 x 10-6 A Moving 3 decimal places to the left, 45000 x 10 -6 becomes 45 x 10-6+3 (add 3 to the exponent) So, 45000 µA = 45 x 10-6 + 3 A = 45 x 10-3 = 45 mA EXAMPLE Add the following: 1) 235000 V + 450 kV = _______ kV Solution: 235000 V = 235 kV So, 235 kV + 450 kV = 685 kV 2) 440 mA + 640000 µA = ________ mA Solution: 640000 µA = 640 mA So, 440 mA + 640 mA = 1080 mA Comparison of AC and DC Direct The DCCurrent electricity, flows in one direction. The flow is said to be from negative to positive. The normal source of a DC electricity, is the dry cell or storage battery. Direct Current The DC electricity, flows in one direction. The flow is said to be from negative to positive. The normal source of a DC electricity, is the dry cell or storage battery. Alternating Current. The AC electricity constantly reverses its direction of flow. It is generated by machine called generator. This type of current is universally accepted because of its limited number of applications with the following advantages. It is easily produced. It is cheaper to maintain. It could be transformed into higher voltage. It could be distributed to far distance with low voltage drop. It is more efficient compared with the direct current.  Comparison of DC Voltage and AC Voltage DC Voltage AC Voltage Fixed Polarity Reverses polarity Has steady (constant) value Varies between reversals in polarity Steady value cannot be stepped Can be stepped up or down up or down by a transformer for electric power distribution Easier to measure Easier to amplify Heating effect is the same in AC and DC