Basic Electricity EAS 199A Lecture Notes Learning Objec=ves Successful comple=on of this module will enable students to Link the basic model of an atom to the flow of electricity Apply the defini=ons of Amp, Volt, Coulomb, Joule, WaM to unit conversions and basic problems involving current and voltage Apply Ohm s Law to simple DC circuits Defini=on Electricity is a form of energy resul2ng from the existence of charged par2cles (such as electrons or protons), either sta2cally as an accumula2on of charge or dynamically as a current. Concise Oxford English Dic=onary, revised 10 th edi=on 1
Defini=on Electricity is a form of energy resul2ng from the existence of charged par2cles (such as electrons or protons), either sta2cally as an accumula2on of charge or dynamically as a current. Concise Oxford English Dic=onary, revised 10 th edi=on Defini=on Conductor: A conductor is a material that readily allows the flow of electricity. A good conductor has a high numerical value of a conduc2vity, and a low numerical value of resistance. Defini=on Conduc+vity: All materials have a measurable property called electrical conduc=vity that indicates the ability of the material to either allow or impede the flow of electrons. Materials that easily conduct electricity have a high conduc=vity. 2
Defini=on Insulator: An insulator is a material that tends to impede the flow of electricity. A resistor has a low numerical value of conduc=vity and high numerical value of resistance. Defini=on Semiconductor: A semiconductor is a material with conduc=vity between that of a conductor and insulator. The conduc=vity of a semiconductor can be changed by exposing it to an electrical field, light, mechanical pressure, or heat. Simplified Func=onal Differences Semiconductors can be used in devices that act like a switch. 3
1.0079 HYDROGEN 6.941 LITHIUM 22.990 SODIUM 39.098 85.468 132.91 (223) BERYLLIUM MAGNESIUM 178.49 (267) 138.91 (227) 8 140.12 232.04 71 140.91 10.811 (98) 186.21 (272) 101.07 (145) 76 150.36 8 80 (285) 10.811 BORON 26.982 114.82 12.011 CARBON 14.007 NITROGEN 15.999 OXYGEN ALUMINIUM SILICON PHOSPHORUS SULPHUR POTASSIUM CALCIUM SCANDIUM TITANIUM VANADIUM CHROMIUM MANGANESE IRON COBALT NICKEL COPPER ZINC GALLIUM GERMANIUM ARSENIC SELENIUM BROMINE RUBIDIUM STRONTIUM YTTRIUM ZIRCONIUM NIOBIUM MOLYBDENUM CAESIUM FRANCIUM BARIUM RADIUM (1) Pure Appl. Chem., 81, No. 11, 2131-2156 (2009) Relative atomic mass is shown with five significant figures. For elements have no stable nuclides, the value enclosed in brackets indicates the mass number of the longest-lived isotope of the element. However three such elements (Th, Pa, and U) do have a characteristic terrestrial isotopic composition, and for these an atomic weight is tabulated. HAFNIUM TANTALUM TUNGSTEN LANTHANUM ACTINIUM GROUP NUMBERS IUPAC RECOMMENDATION (1985) ATOMIC NUMBER CERIUM SYMBOL BORON TECHNETIUM PRASEODYMIUM NEODYMIUM THORIUM PROTACTINIUM URANIUM GROUP NUMBERS CHEMICAL ABSTRACT SERVICE (1986) RELATIVE ATOMIC MASS (1) ELEMENT NAME RUTHERFORDIUM DUBNIUM SEABORGIUM BOHRIUM HASSIUM MEITNERIUM RUTHENIUM RHODIUM PALLADIUM SILVER CADMIUM 18.998 FLUORINE 35.453 CHLORINE RHENIUM OSMIUM IRIDIUM PLATINUM GOLD MERCURY THALLIUM LEAD BISMUTH POLONIUM ASTATINE PROMETHIUM DARMSTADTIUM ROENTGENIUM COPERNICIUM INDIUM TIN ANTIMONY TELLURIUM IODINE 93 (237) 94 (244) 95 (243) 96 (247) 97 (247) 98 (251) 99 (252) 100 (257) 101 (258) 102 (259) 20.180 39.948 83.798 131.29 (222) Copyright 2010 Eni Generalic SAMARIUM EUROPIUM GADOLINIUM TERBIUM DYSPROSIUM HOLMIUM ERBIUM THULIUM YTTERBIUM NEPTUNIUM PLUTONIUM AMERICIUM CURIUM BERKELIUM CALIFORNIUM EINSTEINIUM FERMIUM MENDELEVIUM NOBELIUM HELIUM NEON ARGON KRYPTON XENON RADON 174.97 LUTETIUM (262) LAWRENCIUM 9/27/11 Elements Pure substances are made of elements. An element consists of atoms Atoms have a nucleus consis=ng of protons and neutrons Electrons move in shells around the nucleus Elements Number of protons determines the element Number of electrons varies State of electrical charge Is the element in a chemical bond? Number of neutrons varies with isotope PERIOD 1 2 3 4 5 6 7 GROUP 1 IA 18 VIIIA 1 h ttp://www.periodni.com 2 4.0026 H He 2 IIA 3 4 9.0122 Li Be 11 12 24.305 57-71 La-Lu 89-103 Ac-Lr Tc Rf Db Sg Bh Hs Mt Pm 13 IIIA 14 IVA 15 VA 16 VIA 17 VIIA 5 6 7 8 9 B C N O F 13 14 28.086 15 30.974 16 32.065 Na Mg Al Si P S Cl VIIIB 3 IIIB 4 IVB 5 VB 6 VIB 7 VIIB 8 9 10 11 IB 12 IIB 19 20 40.078 21 44.956 22 47.867 23 50.942 24 51.996 25 54.938 26 55.845 27 58.933 28 58.693 29 63.546 30 65.38 31 69.723 32 72.64 33 74.922 34 78.96 35 79.904 K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br 37 38 87.62 39 88.906 40 91.224 41 92.906 42 95.96 Rb Sr 55 56 137.33 Cs Ba 87 88 (226) Fr Ra PERIODIC TABLE OF THE ELEMENTS Y Lanthanide Actinide Zr Nb LANTHANIDE 57 58 La Ce Mo 72 73 180.95 74 183.84 Hf Ta W ACTINIDE 89 Ac 90 91 231.04 92 238.03 Th 59 60 144.24 Pr Pa 13 IIIA 5 B 43 44 45 102.91 46 106.42 47 107.87 48 112.41 49 50 118.71 51 121.76 52 127.60 53 126.90 Ru Rh Pd Ag Cd 75 76 190.23 77 192.22 78 195.08 79 196.97 80 200.59 81 204.38 82 207.2 83 208.98 84 (209) 85 (210) Re Os Ir Pt Au Hg Tl Pb Bi Po At 104 105 (26 ) 106 (2 ) 107 108 (277) 109 (2 ) 110 (2 1) 111 (2 ) Nd U 61 Sm Ds Np Pu Am Cm Bk Cf Es Fm Md No In 62 63 151.96 64 157.25 65 158.93 66 162.50 67 164.93 68 167.26 69 168.93 70 173.05 Eu Rg Gd 112 Cn Tb Dy Sn Ho Sb Er Te Tm 17 I Yb 10 Ne 18 36 Kr 54 Ar Xe 86 Rn 71 103 Lu Lr 4
Periodic Table: Copper Bohr Model of the atom (Cu) Electrical current in a trivial circuit Conductor + Battery 5
Electrical current: atomic model + Battery Electrical Current: electron flow + Battery Electrical Current: electron flow Electron flow: negative to positive + Battery 6
Electrical Current: current conven=on Current flow: positive to negative Electron flow: negative to positive + Battery How many electrons? How many electrons? 7
Electrical current: poten=al Electrical current: electron flow Electrical current: conven=on 8
Defini=on: Charge Elementary charge 1 electron = 1.602 10 19 coulomb Coulomb 1 coulomb= 6.24 10 18 electrons Defini=on: Current 1A = 1 C s 1 C = 6.24 "10 18 electrons Defini=on: Voltage J 1V = 1 coulomb 9
Voltage and electrical work A e B If the voltage between A and B is one volt, then one Joule of work is done when 6.28 10 18 electrons move from A to B. V Ohm s Law R V = IR I Ohm s Law 10
Ohm s Law Ohm s Law Ohm s Law 11
Example: Current through a light bulb A 1.5 volt AA bamery is wired to a light bulb with a resistance of 30 Ω. a. Sketch the components. b. Draw the circuit. c. Find the current flowing through the light bulb. Example: Current through a light bulb A 1.5 volt AA bamery is wired to a light bulb with a resistance of 30 Ω. a. Sketch the components. Example: Current through a light bulb A 1.5 volt AA bamery is wired to a light bulb with a resistance of 30 Ω. a. Sketch the components. b. Draw the circuit. 12
Example: Current through a light bulb c. Find the current flowing through the bulb Apply Ohm s Law to the loop V = I R V and R and known, so solve for I I = V/R Subs=tute the known values and compute the value of I I = 1.5V = 0.05 A = 50 ma 30! where 1 A = 1000 ma. 13