Electric Currents and Simple Circuits


 Blake Gregory
 4 years ago
 Views:
Transcription
1 1 Electric Currents and Simple Circuits Electrons can flow along inside a metal wire if there is an Efield present to push them along ( F= qe). The flow of electrons in a wire is similar to the flow of water in a pipe. Definition: electric current Q = = rate of flow of charge t units [ ] = coulomb/second = 1 C / 1 s = 1 ampere () = "amp" "t's not the voltage that kills you, it the amps." bout 0.05 is enough to kill you. f current = 1 in a wire, then 1 coulomb of charge flows past any point every second. n electrostatic problems, E = 0 inside a metal, but if 0, then the situation is not static, the Efield is not zero. Electrons flow in metals, not protons, so ( ) charges are moving when there is a current. The electron feel a force F= ee a nd goes E "upstream" against the Efield. The flow of ( ) charge in one direction is electrically equivalent to the flow of (+) charge in the opposite direction: neutral plates ( ) or (+) either way, get:
2 2 By convention, we define current as the flow of imaginary (+) charges, when it is really ( ) charges flowing the other way: (Some texts refer to as the "conventional current" to distinguish it from the "electron current".) Example: How many electrons flow past per second when the current is 1? Q N e N 1 1C/s = = = = = = s t t t e C C 18 1 bout 0.01 = 10 m flowing though your heart is lethal, yet could grab a wire carrying 1000 and be safe! Why? Because my body has a much higher electrical resistance than the metal. The electrons prefer to flow through the metal wire. For most materials, the current is proportional to the voltage difference between the ends. E (since F = q E) and E, so hi E lo From now on, we usually follow the (bad) convention and write "" when we really mean " ". ( really ) = constant Definition of resistance (of a piece of wire or other material): The experimental fact that (for most materials) the ratio = / is a constant, independent of or, is called Ohm's Law : = = constant, usually written = ( constant) Units: [] = volt / ampere = ohm (Ω) ["Ω" is Greek letter omega]
3 3 Ohm's Law should be written =, but the bad convention is to write =. "Ohm's Law" is not really a law, because it is not always true. For many materials, Ohm's Law is approximately true, the resistance is approximately constant, independent of or. Materials that obey Ohm's Law are called "ohmic materials". But some materials are "nonohmic"; they do not obey Ohm's Law. The average speed of electrons in a currentcarrying wire results from a competition between two effects: (1) the Efield, which causes an acceleration according to F = qe = m a, making the electrons go faster and faster, and (2) the scattering of electrons due to impurities and thermal vibrations, which act like friction, making the electrons slow down. For typical currents in real wires, the average electron speed (often called the drift velocity) is actually quite slow, typically less than 0.1 mm/s. (ncidentally, the term drift velocity is incorrect, it should be called the drift speed.) material with lots of electron scattering has a high resistance: wire << 1 Ω, human 10 5 Ω Ω 4 = = = 10 ( Ω harmless) 3 = = = 10 (painful!) 5 10 safe, 100 dangerous! The resistance of a piece of material depends on its shape and composition. Shape: long and skinny big short and fat small just like the flow of water through a pipe. Long skinny water pipes resist flow of water. L Turns out that, L area so big L means big, big means small
4 4 ρ L = ρ (Greek letter "rho") = resistivity ( We show were this comes in the next section below.) esistivity ρ depends on the material composition, not on the shape. ρ is a measure of the scattering of electrons in that material, like viscosity of fluid in a pipe. Big ρ means lots of scattering (friction), big resistance to flow. Units: ρ = [ ρ ] = [] length = Ω m L length length length material ρ use Cu Ω m house wiring l Ω m power lines W (tungsten) Ω m (cool) light bulb filaments Ω m (hot) Fe Ω m not used in wiring glass Ω m electrical insulator Microscopic view of Ohm's Law. Definition: current density J = (current per area in a conductor). We also define current density vector J where direction of J is the direction of the current. J is related to the average speed v drift of the charge carriers (usually electrons) by J = n q v drift, n is the number of carrier per volume, q is the charge per carrier (usually q = e). Proof: Consider a wire with carrier density n (#/volume), crosssectional area, and drift speed v drift. n a time t, all the charges move an average distance x = v drift t.
5 5 area volume = x The charge Q in the length of wire x is J x = v drift t number of carriers charge Q = volume n q x volume carrier = So the current density is J Q 1 nq x = = = = t t nqv Done. drift n ohmic materials, the current density J is proportional to the electric field E J = σ E, where the proportionality constant σ is called the conductivity. 1 The resistivity ρ is defined as ρ = and so E = ρ J. σ J= σ E or E = ρ J, where ρ = 1/σ = constant is the microscopic version of Ohm's Law. We now show that this is equivalent to = : Consider a cylindrical section of conductor, length L, crosssectional area, with current density J, and Efield E. Start with E = ρ J, now multiply both sides by L and write J J, E as J = /. EL = ρ L. Notice that = E L. So L ρ L we have =, or =, where we have defined the resistance as Ohm's Law =, where ρ L =. We have just shown that E = ρ J is the same as ρ L =.
6 6 Simple Circuit Some electrical circuits symbols: resistor capacitor C switch battery ( ) side E or (+) side battery's job is to maintain a constant voltage difference between its terminals. t acts like a charge pump, pushing (+) charge inside the battery from the ( ) side to the (+) side. This is the direction that the charges don't want to go. The battery has to do chemical work to push the charges "uphill" (toward higher electrostatic PE). "10volt battery" means voltage across battery = E or (or just ) = 10 volts = 10. Hence the confusing equation: = 10, meaning "the voltage difference across battery is 10 volts". = +10 switch open switch closed = +10 battery = 0 wire = 50 Ω (carbon resistor) = 0 lways assume that the wires connecting circuit elements have zero resistance wire = 0 no voltage change along the wire, since wire = wire = 0 = 0. Current around the circuit is: 10 = = = Ω ecall that (+) charge tends toward low voltage. Can think of voltage as a kind of "electrical pressure". Water in a pipe flows from high pressure to low pressure. Likewise, (+) charges in a wire flow from hi to lo. n the waterpipe analogy, we can think of a resistor as like a porous plug of gravel in the pipe. The gravel plug offers resistance to the flow of water, so we need a large pressure difference to push the water through.
7 7 f no pressure difference across a pipe plug, then no water flows. f no voltage difference across a resistor, then no current flows. hi P flow lo P hi lo gravel plug in waterfilled pipe = = nside a resistor, (+) charge flows from hi lo ("downhill") nside a battery, (+) charge flows from lo hi ("uphill"). Current is the same in the battery and the resistor, just as water flow (in gallons per minute) is same through pump and through gravel plug. hi pressure hi Pump gravel lo pressure lo Electrical Power When is big, gets hot because the flowing electrons are scattered friction. ecall that power P = rate at which energy is transformed = rate at which work is done P W, t [P] joule = = second 1watt (W) n a resistor, the rate at which electrostatic PE is converted into thermal energy (heat) is P = ( really, P = ) f = constant, then the average speed of electrons is constant KE = (1/2)mv 2 = constant.
8 8 When an amount of charge Q flows through a resistor in a time t, from the high side to the low side, the change in PE of that charge is PE = Q. The PE of the charge Q is decreased, but KE = constant. Where did the energy go? nswer: into thermal energy P PE Q = = = t t P = and = P = ( ) = 2 or P = ( / ) = 2 / 3 equivalent expressions for power: 2 2 P = = = "100 W bulb" uses P = 100 W. Light bulbs and most other appliances (T, coffee grinder) are designed to work with voltage = 120 (really = 120 ). example of electrical power: What is the current through a 100 W light bulb? What is its resistance (when on and hot). P 100W = 0.83 = 120 =, ( ) P = = = = 144Ω P 100 W
Electron Theory of Charge. Electricity. 1. Matter is made of atoms. Refers to the generation of or the possession of electric charge.
Electricity Refers to the generation of or the possession of electric charge. There are two kinds of electricity: 1. Static Electricity the electric charges are "still" or static 2. Current Electricity
More informationNotes on Electricity (Circuits)
A circuit is defined to be a collection of energygivers (batteries) and energytakers (resistors, light bulbs, radios, etc.) that form a closed path (or complete path) through which electrical current
More informationCHAPTER 1 ELECTRICITY
CHAPTER 1 ELECTRICITY Electric Current: The amount of charge flowing through a particular area in unit time. In other words, it is the rate of flow of electric charges. Electric Circuit: Electric circuit
More informationDynamic Electricity. All you need to be an inventor is a good imagination and a pile of junk. Thomas Edison
Dynamic Electricity All you need to be an inventor is a good imagination and a pile of junk. Thomas Edison Review Everything is made of atoms which contain POSITIVE particles called PROTONS and NEGATIVE
More informationElectroscope Used to are transferred to the and Foil becomes and
Electricity Notes Chapter 17 Section 1: Electric Charge and Forces Electric charge is a variety of independent all with one single name. Electricity is related to, and both () and (+) carry a charge.
More informationChapter 17. Current and Resistance. Sections: 1, 3, 4, 6, 7, 9
Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Equations: 2 2 1 e r q q F = k 2 e o r Q k q F E = = I R V = A L R ρ = )] ( 1 [ o o T T + = α ρ ρ V I V t Q P = = R V R I P 2 2 ) ( = = C Q
More informationChapter 27 Current and Resistance 27.1 Electric Current
Chapter 27 Current and esistance 27.1 Electric Current Electric current: dq dt, unit: ampere 1A = 1C s The rate at which charge flows through a surface. No longer have static equilibrium. E and Q can 0
More informationSection 1 Electric Charge and Force
CHAPTER OUTLINE Section 1 Electric Charge and Force Key Idea questions > What are the different kinds of electric charge? > How do materials become charged when rubbed together? > What force is responsible
More informationELECTRICITY. Electric Circuit. What do you already know about it? Do Smarty Demo 5/30/2010. Electric Current. Voltage? Resistance? Current?
ELECTRICITY What do you already know about it? Voltage? Resistance? Current? Do Smarty Demo 1 Electric Circuit A path over which electrons travel, out through the negative terminal, through the conductor,
More informationElectric Current & DC Circuits
Electric Current & DC Circuits Circuits Click on the topic to go to that section Conductors Resistivity and Resistance Circuit Diagrams Measurement EMF & Terminal Voltage Kirchhoff's Rules Capacitors*
More informationCurrent and Resistance
Current and Resistance 1 Define the current. Understand the microscopic description of current. Discuss the rat at which the power transfer to a device in an electric current. 2 21 Electric current 22
More informationElectricity. Chapter 21
Electricity Chapter 21 Electricity Charge of proton Positive Charge of electron Negative Charge of neutron NONE Atoms have no charge because the charges of the protons and electrons cancel each other out.
More informationNotes on Electricity (Circuits)
A circuit is defined to be a collection of energygivers (active elements) and energytakers (passive elements) that form a closed path (or complete path) through which electrical current can flow. The
More informationGreek Letter Omega Ω = Ohm (Volts per Ampere)
) What is electric current? Flow of Electric Charge 2) What is the unit we use for electric current? Amperes (Coulombs per Second) 3) What is electrical resistance? Resistance to Electric Current 4) What
More informationElectricity Courseware Instructions
Physics Electricity Courseware Instructions This courseware acts as a supplement to the classroom instruction. The five sections on the following slide link to the topic areas. Following the topic area
More informationMonday July 14. Capacitance demo slide 19 Capacitors in series and parallel slide 33 Elmo example
Monday July 14 Lecture 5 Capacitance demo slide 19 Capacitors in series and parallel slide 33 Elmo example Lecture 6 Currents and esistance Lecture 9 Circuits Wear Microphone 1 3 Lecture 6 Current and
More informationCLASS X ELECTRICITY
Conductor Insulator: Materia Materials through which electric current cannot pass are called insulators. Electric Circuit: A continuous a CLASS X ELECTRICITY als through which electric current can pass
More informationChapter 27: Current and Resistance
Chapter 7: Current and esistance In this section of the course we will be studying the flow of electric charge, current, in a circuit. We have already seen electric current when we first discussed electric
More information16.1 Electrical Current
16.1 Electrical Current Electric Current Electric Current When the ends of an electric conductor are at different electric potentials, charge flows from one end to the other Flow of Charge Charge flows
More informationElectricity. dronstudy.com
Electricity Electricity is a basic part of our nature and it is one of our most widely used forms of energy. We use electricity virtually every minute of every day for example in lighting, heating, refrigeration,
More informationElectrostatics and Charge. Creating Electric Fields
Electrostatics and Charge Creating Electric Fields Electric Charges Recall that all matter is made of atoms. Neutral atoms can acquire a charge in several different ways, all of which require movement
More information10/14/2018. Current. Current. QuickCheck 30.3
Current If QCurrent is the total amount of charge that has moved past a point in a wire, we define the current I in the wire to be the rate of charge flow: The SI unit for current is the coulomb per second,
More informationElectrical Circuits. Sources of Voltage
Electrical Circuits ALESSANDRO VOLTA (17451827) ANDRE MARIE AMPERE (17751836) GEORG SIMON OHM (17891854) POTENTIAL IN VOLTS, CURRENT IN AMPS, RESISTANCE IN OHMS! Sources of Voltage Voltage, also known
More informationElectric Current & DC Circuits How to Use this File Electric Current & DC Circuits Click on the topic to go to that section Circuits
Slide 1 / 127 Slide 2 / 127 Electric Current & DC Circuits www.njctl.org Slide 3 / 127 How to Use this File Slide 4 / 127 Electric Current & DC Circuits Each topic is composed of brief direct instruction
More informationElectricity. Prepared by Juan Blázquez, Alissa Gildemann. Electric charge is a property of all objects. It is responsible for electrical phenomena.
Unit 11 Electricity 1. Electric charge Electric charge is a property of all objects. It is responsible for electrical phenomena. Electrical phenomena are caused by the forces of attraction and repulsion.
More informationElectricity CHARGE. q = 1.6 x1019 C
Electricity CHARGE q = 1.6 x1019 C How many protons in a Coulomb? 19 1.00 C x (1 proton) / (1.60 x 10 C) = 18 6.25x10 protons! Opposites Attract Most materials are Electrically NEUTRAL (lowest potential
More informationCircuits. Electric Current & DC Circuits. Slide 1 / 127. Slide 2 / 127. Slide 3 / 127. Slide 4 / 127. Slide 5 / 127. Slide 6 / 127
Slide 1 / 127 Slide 2 / 127 New Jersey Center for Teaching and Learning Electric Current & DC Circuits www.njctl.org Progressive Science Initiative This material is made freely available at www.njctl.org
More informationInsulators Nonmetals are very good insulators; their electrons are very tightly bonded and cannot move.
SESSION 11: ELECTRIC CIRCUITS Key Concepts Resistance and Ohm s laws Ohmic and nonohmic conductors Series and parallel connection Energy in an electric circuit Xplanation 1. CONDUCTORS AND INSULATORS
More informationElectric Charge. Electric Charge ( q ) unbalanced charges positive and negative charges. n Units Coulombs (C)
Electric Charge Electric Charge ( q ) unbalanced charges positive and negative charges n Units Coulombs (C) Electric Charge How do objects become charged? Types of materials Conductors materials in which
More information670 Intro Physics Notes: Electric Current and Circuits
Name: Electric Current Date: / / 670 Intro Physics Notes: Electric Current and Circuits 1. Previously, we learned about static electricity. Static electricity deals with charges that are at rest. 2. Now
More informationStatic Electricity. Electric Field. the net accumulation of electric charges on an object
Static Electricity the net accumulation of electric charges on an object Electric Field force exerted by an e  on anything that has an electric charge opposite charges attract like charges repel Static
More informationElectricity
Electricity Electric Charge There are two fundamental charges in the universe. Positive (proton) has a charge of +1.60 x 1019 C Negative (electron) has a charge of 1.60 x 1019 C There is one general
More informationFor an electric current to flow between two points, two conditions must be met.
ELECTROSTATICS LAB Electric Circuits For an electric current to flow between two points, two conditions must be met. 1. There must be a conducting path between the points along which the charges can move.
More informationReview. Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.
Review Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. When more devices are added to a series circuit, the total circuit resistance: a.
More informationChapter 21 Electric Current and Circuits
Chapter 21 Electric Current and Circuits 1 As an introduction to this chapter you should view the following movie. If you cannot click on the link, then copy it and paste it into your web browser. http://www.ionaphysics.org/movies/vir.mp4
More informationNote on Posted Slides. Flow of Charge. Electricity/Water Analogy: Continuing the Analogy. Electric Current
Note on Posted Slides These are the slides that I intended to show in class on Tue. Mar. 18, 2014. They contain important ideas and questions from your reading. Due to time constraints, I was probably
More informationDirect Current (DC) Circuits
Direct Current (DC) Circuits NOTE: There are short answer analysis questions in the Participation section the informal lab report. emember to include these answers in your lab notebook as they will be
More informationAC vs. DC Circuits. Constant voltage circuits. The voltage from an outlet is alternating voltage
Circuits AC vs. DC Circuits Constant voltage circuits Typically referred to as direct current or DC Computers, logic circuits, and battery operated devices are examples of DC circuits The voltage from
More informationProtons = Charge Electrons = Charge Neutrons = Charge. When Protons = Electrons, atoms are said to be ELECTRICALLY NEUTRAL (no net charge)
QUICK WRITE: For 2 minutes, write the three parts of an atom and what their charges are. Explain what creates an electric charge (positive or negative) on something. Rules  You MUST write for the entire
More informationPhysics 1B Electricity & Magnetism. Frank Wuerthwein (Prof) Edward Ronan (TA) UCSD
Physics 1B Electricity & Magnetism Frank Wuerthwein (Prof) Edward Ronan (TA) UCSD Quiz 1 Quiz 1A and it s answer key is online at course web site. http://hepuser.ucsd.edu/twiki2/bin/view/ UCSDTier2/Physics1BWinter2012
More informationChapter 8: E & M (Electricity & Magnetism or Electromagnetism)
Chapter 8: E & M (Electricity & Magnetism or Electromagnetism) Charge conservation&quantization (review from last class) Electric current & circuits Resistance & Ohm s Law Concept of FIELD (electric/magnetic/gravitational)
More informationChapter 17 Electric Current and Resistance Pearson Education, Inc.c
Chapter 17 Electric Current and Resistance 2010 Pearson Education, Inc.c 1 Units of Chapter 17 Batteries and Direct Current Current and Drift Velocity Resistance and Ohm s Law Electric Power 2010 Pearson
More informationChapter 25 Electric Currents and. Copyright 2009 Pearson Education, Inc.
Chapter 25 Electric Currents and Resistance 251 The Electric Battery Volta discovered that electricity could be created if dissimilar metals were connected by a conductive solution called an electrolyte.
More informationChapter 16. Current and Drift Speed. Electric Current, cont. Current and Drift Speed, cont. Current and Drift Speed, final
Chapter 6 Current, esistance, and Direct Current Circuits Electric Current Whenever electric charges of like signs move, an electric current is said to exist The current is the rate at which the charge
More informationSection 1: Electric Charge and Force
Electricity Section 1 Section 1: Electric Charge and Force Preview Key Ideas Bellringer Electric Charge Transfer of Electric Charge Induced Charges Charging by Contact Electric Force Electric Field Lines
More informationConceptual Physical Science 6 th Edition
Conceptual Physical Science 6 th Edition Chapter 8: STATIC AND CURRENT ELECTRICITY 1 Chapter 8: STATIC AND CURRENT ELECTRICITY Chapter 8: Read: All Homework: Four problems from the following set: 4, 6,
More informationElectric Current. Chapter 17. Electric Current, cont QUICK QUIZ Current and Resistance. Sections: 1, 3, 4, 6, 7, 9
Electric Current Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Whenever electric charges of like signs move, an electric current is said to exist The current is the rate at which the charge
More informationCircuits. Electric Current & DC Circuits Circuits. Unit 6. April Electric Current. Electric Current. Electric Current. ΔQ Δt
Electric Current & DC Circuits Electric Current & DC Circuits Circuits Conductors esistivity and esistance Click on the topic to go to that section Circuit Diagrams Measurement Electric Current Circuits
More informationLecture 6 Current and Resistance Ch. 26
Lecture 6 Current and esistance Ch. 6 Cartoon nvention of the battery and Voltaic Cell Warmup problem Topics What is current? Current density Conservation of Current esistance Temperature dependence
More informationElectric charges. Basics of Electricity
Electric charges Basics of Electricity Electron has a negative charge Neutron has a no charge Proton has a positive charge But what is a charge? Electric charge, like mass, is a fundamental property of
More informationElectricity Worksheet (p.1) All questions should be answered on your own paper.
Electricity Worksheet (p.1) 1. In terms of attraction and repulsion, how do negative particles affect negative particles? How do negatives affect positives? 2. What happens to electrons in any charging
More information6. In a dry cell electrical energy is obtained due to the conversion of:
1. If a wire of uniform area of cross section is cut into two halves (equal in size), the resistivity of each part will be: a) Halved. b) Doubled. c) Becomes four times its initial value. d) Remains the
More information10 N acts on a charge in an electric field of strength 250 N.C What is the value of the charge?
Year 11 Physics Electrical Energy in the Home Name: 1. Draw the electric field lines around a) a single positive charge b) between two opposite charged bodies c) two parallel plates + + + + + + +   
More informationPhysics 1502: Lecture 8 Today s Agenda. Today s Topic :
Physics 1502: Lecture 8 Today s Agenda Announcements: Lectures posted on: www.phys.uconn.edu/~rcote/ HW assignments, solutions etc. Homework #3: On Masterphysics today: due next Friday Go to masteringphysics.com
More informationELECTRICITY. Chapter ELECTRIC CHARGE & FORCE
ELECTRICITY Chapter 17 17.1 ELECTRIC CHARGE & FORCE Essential Questions: What are the different kinds of electric charge? How do materials become charged when rubbed together? What force is responsible
More informationWhat is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another.
Electricity What is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another. What is electrical charge Protons carry positive charges
More informationPhysics 142 Steady Currents Page 1. Steady Currents
Physics 142 Steady Currents Page 1 Steady Currents If at first you don t succeed, try, try again. Then quit. No sense being a damn fool about it. W.C. Fields Electric current: the slow average drift of
More informationGas discharges. Current flow of electric charge. Electric current (symbol I) L 26 Electricity and Magnetism [3] examples of electrical discharges
L 26 Electricity and Magnetism [3] Electric circuits what conducts electricity what doesn t t conduct electricity Current voltage and resistance Ohm s s Law Heat in a resistor power loss Making simple
More information1 of 23. Boardworks Ltd Electrical Power
1 of 23 Boardworks Ltd 2016 Electrical Power Electrical Power 2 of 23 Boardworks Ltd 2016 What is electrical power? 3 of 23 Boardworks Ltd 2016 Electrical power is the rate at which energy is transferred
More informationAlgebra Based Physics
Page 1 of 105 Algebra Based Physics Electric Current & DC Circuits 20151006 www.njctl.org Page 2 of 105 Electric Current & DC Circuits Circuits Conductors Resistivity and Resistance Circuit Diagrams
More informationClosed loop of moving charges (electrons move  flow of negative charges; positive ions move  flow of positive charges. Nucleus not moving)
Unit 2: Electricity and Magnetism Lesson 3: Simple Circuits Electric circuits transfer energy. Electrical energy is converted into light, heat, sound, mechanical work, etc. The byproduct of any circuit
More informationElectric Current. Volta
Electric Current Galvani Volta In the late 1700's Luigi Galvani and Alessandro Volta carried out experiements dealing with the contraction of frogs' leg muscles. Volta's work led to the invention of the
More informationPH 102 Exam I N N N N. 3. Which of the following is true for the electric force and not true for the gravitational force?
Name Date INSTRUCTIONS PH 102 Exam I 1. nswer all questions below. ll problems have equal weight. 2. Clearly mark the answer you choose by filling in the adjacent circle. 3. There will be no partial credit
More informationChapter 25: Electric Current
Chapter 25: Electric Current Conductors and Charge Carriers Consider a conducting piece of metal: The valence electrons are weakly bound to the nuclei form a fluidlike sea of electrons that can move through
More information(b) State the relation between work, charge and potential difference for an electric circuit.
Question Bank on ChElectricity 1. (a) Define the S.I unit of potential difference. (b) State the relation between work, charge and potential difference for an electric circuit. Calculate the potential
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 7 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm s law http://www.physics.wayne.edu/~apetrov/phy2140/
More informationDEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS
DEL PHYSCS THE BADDEST CLASS ON CAMPUS B PHYSCS TSOKOS LESSON 54: ELECTRC CURRENT AND ELECTRC RESSTANCE Reading Activity Questions? Objectives By the end of this class you should be able to: Q State the
More informationElectric Charges & Current. Chapter 12. Types of electric charge
Electric Charges & Current Chapter 12 Types of electric charge Protons w/ + charge stuck in the nucleus Electrons w/  charge freely moving around the nucleus in orbits 1 Conductors Allow the easy flow
More informationCircuits. Circuits. Electric Current & DC Circuits. current and circuits presentation March 22, How to Use this File.
New Jersey Center for Teaching and Learning Electric Current & DC Circuits Progressive Science Initiative This material is made freely available at www.njctl.org and is intended for the non commercial
More informationhttps://www.youtube.com/watch?v=yc2363miqs
https://www.youtube.com/watch?v=yc2363miqs SCIENCE 9 UNIT 3 ELECTRICITY Remember: In the last unit we learned that all matter is made up of atoms atoms have subatomic particles called, protons, neutrons
More informationChapter 20 Electric Circuits
Chapter 0 Electric Circuits Chevy olt  Electric vehicle of the future Goals for Chapter 9 To understand the concept of current. To study resistance and Ohm s Law. To observe examples of electromotive
More informationContinuous flow of electric charges. Current Electricity
Continuous flow of electric charges Current Electricity Did You Know? The voltage across a muscle cell in your body is about 70 millivolts. A millivolt (mv) is one thousandth of a volt. AC and DC DC Direct
More informationRead Chapter 7; pages:
Forces Read Chapter 7; pages: 191221 Objectives:  Describe how electrical charges exert forces on each other; Compare the strengths of electric and gravitational forces; Distinguish between conductors
More informationELECTRIC CURRENT INTRODUCTION. Introduction. Electric current
Chapter 7 ELECTRIC CURRENT Introduction Electric current Charge conservation Electric conductivity Microscopic picture Electric power Electromotive force Kirchhoff s rules Summary INTRODUCTION The first
More informationElectrical Forces arise from particles in atoms.
Electrostatics Electrical Forces arise from particles in atoms. The protons(+) in the nucleus attract the electrons and hold them in orbit Electrons()repel other electrons and protons repel other protons
More informationSome differences: Some basic similarities: Charges. Electrons vs. Protons 4/3/15. Chapters 2225: Electromagnetism!
Chapters 2225: Electromagnetism! Electric Force vs. Gravitational Force What properties does the gravitational force depend on? What properties does the electric force depend on? F grav = Gm 1 m 2 /d
More informationWhat are the two types of current? The two types of current are direct current and alternating current.
Electric Current What are the two types of current? The two types of current are direct current and alternating current. Electric Current The continuous flow of electric charge is an electric current.
More informationChapter 27. Current And Resistance
Chapter 27 Current And Resistance Electric Current Electric current is the rate of flow of charge through some region of space The SI unit of current is the ampere (A) 1 A = 1 C / s The symbol for electric
More informationElectric Currents and Resistance II
Electric Currents and Resistance II Physics 2415 Lecture 11 Michael Fowler, UVa Today s Topics First we ll mention capacitors Power usage: kwh, etc. The microscopic picture Temperature dependence of resistivity
More informationAP Physics C. Electric Circuits III.C
AP Physics C Electric Circuits III.C III.C.1 Current, Resistance and Power The direction of conventional current Suppose the crosssectional area of the conductor changes. If a conductor has no current,
More informationFlow Rate is the NET amount of water passing through a surface per unit time
Electric Current An Analogy Water Flow in a Pipe H 2 0 gallons/minute Flow Rate is the NET amount of water passing through a surface per unit time Individual molecules are bouncing around with speeds of
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 4 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm s law resistivity
More information3 Electric current, resistance, energy and power
3 3.1 Introduction Having looked at static charges, we will now look at moving charges in the form of electric current. We will examine how current passes through conductors and the nature of resistance
More informationRECALL?? Electricity concepts in Grade 9. Sources of electrical energy Current Voltage Resistance Power Circuits : Series and Parallel
Unit 3C Circuits RECALL?? Electricity concepts in Grade 9. Sources of electrical energy Current Voltage Resistance Power Circuits : Series and Parallel 2 Types of Electricity Electrostatics Electricity
More informationUnit 2 Electrical Quantities and Ohm s Law
Electrical Quantities and Ohm s Law Objectives: Define a coulomb. Define an ampere. Define a volt. Define an ohm. Define a watt. Objectives: Compute electrical values using Ohm s law. Discuss basic types
More informationChapter 3: Electric Current And DirectCurrent Circuits
Chapter 3: Electric Current And DirectCurrent Circuits 3.1 Electric Conduction 3.1.1 Describe the microscopic model of current Mechanism of Electric Conduction in Metals Before applying electric field
More informationPHYSICS. Chapter 27 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT
PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 27 Lecture RANDALL D. KNIGHT Chapter 27 Current and Resistance IN THIS CHAPTER, you will learn how and why charge moves through a wire
More informationChapters 24/25: Current, Circuits & Ohm s law Thursday September 29 th **Register your iclickers**
Chapters 24/25: Current, Circuits & Ohm s law Thursday September 29 th **Register your iclickers** Conductors under dynamic conditions Current, current density, drift velocity Ohm s law Types of conductor
More informationUniversity Physics (PHY 2326)
Chapter 25 University Physics (PHY 2326) Lecture 7 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm
More informationChapter 25 Current, Resistance, and Electromotive Force
Chapter 25 Current, Resistance, and Electromotive Force Lecture by Dr. Hebin Li Goals for Chapter 25 To understand current and how charges move in a conductor To understand resistivity and conductivity
More informationCoulomb s constant k = 9x10 9 N m 2 /C 2
1 Part 2: Electric Potential 2.1: Potential (Voltage) & Potential Energy q 2 Potential Energy of Point Charges Symbol U mks units [Joules = J] q 1 r Two point charges share an electric potential energy
More informationPhysics 11b Lecture #8
Physics 11b Lecture #8 Current and Resistance S&J Chapter 27 Administravia First midterm this Thursday Covers up to and including capacitance Lectures #1 #7, textbook chapters 23 26 Five problems Problem
More informationOhms Law. V = IR V = voltage in volts (aka potential difference) I = Current in amps R = resistance in ohms (Ω)
Ohms Law V = IR V = voltage in volts (aka potential difference) I = Current in amps R = resistance in ohms (Ω) Current How would you define it? Current the movement of electric charge through a medium
More informationRevision checklist SP10. SP10 Electricity and Circuits. SP10a Electric circuits. SP10b Current and potential difference
Electricity and Circuits a Electric circuits Describe the basic structure of an atom (positions, relative masses and relative charges of protons, neutrons and electrons). Recognise the circuit symbols
More informationElectricity Review completed.notebook. June 13, 2013
Which particle in an atom has no electric charge associated with it? a. proton c. neutron b. electron d. nucleus Jun 12 9:28 PM The electrons in a metal sphere can be made to move by touching it with a
More informationPreliminary Course Physics Module 8.3 Electrical Energy in the Home Summative Test. Student Name:
Summative Test Student Name: Date: / / IMPORTANT FORMULAE I = Q/t V = I.R R S = R 1 + R 2 +.. 1/R P = 1/R 1 + 1/R 2 + P = V.I = I 2.R = V 2 /R Energy = V.I.t E = F/q Part A. Multiple Choice Questions 120.
More informationLook over Chapter 26 sections 17 Examples 3, 7. Look over Chapter 18 sections 15, 8 over examples 1, 2, 5, 8, 9,
Look over Chapter 26 sections 17 Examples 3, 7 Look over Chapter 18 sections 15, 8 over examples 1, 2, 5, 8, 9, 1)How to find a current in a wire. 2)What the Current Density and Draft Speed are. 3)What
More informationAP Physics C  E & M
Slide 1 / 27 Slide 2 / 27 AP Physics C  E & M Current, Resistance & Electromotive Force 20151205 www.njctl.org Slide 3 / 27 Electric Current Electric Current is defined as the movement of charge from
More informationElectric charge is conserved the arithmetic sum of the total charge cannot change in any interaction.
Electrostatics Electric charge is conserved the arithmetic sum of the total charge cannot change in any interaction. Electric Charge in the Atom Atom: Nucleus (small, massive, positive charge) Electron
More informationChapter 33  Electric Fields and Potential. Chapter 34  Electric Current
Chapter 33  Electric Fields and Potential Chapter 34  Electric Current Electric Force acts through a field An electric field surrounds every electric charge. It exerts a force that causes electric charges
More information