Register now to access 7 million high quality study materials (What's Course Hero?) Course Hero is the premier provider of high quality online educational resources. With millions of study documents, online tutors, digital flashcards and free courseware, Course Hero is helping students learn more efficiently and effectively. Whether you're interested in exploring new subjects or mastering key topics for your next exam, Course Hero has the tools you need to achieve your goals.

32 Pages

Physics II - Lecture 3 (Current&Resistance)

Course: PHYS 1200, Spring 2011
School: Rensselaer
Rating:

Word Count: 1392

Document Preview

1200 Physics Lecture 2 - F2011 Current and Current density Resistivity and Resistance Power dissipation Capacitance Calculating capacitance Energy storage 1 Current and Current Density Resistivity and Resistance Ohms Law Power dissipation 2 Electric Current Charge flow is produced when an electric field is applied to charges. Positive charges flow in the direction of the electric field, negative charges move...

Register Now

Unformatted Document Excerpt

Coursehero >> New York >> Rensselaer >> PHYS 1200

Course Hero has millions of student submitted documents similar to the one
below including study guides, practice problems, reference materials, practice exams, textbook help and tutor support.

Course Hero has millions of student submitted documents similar to the one below including study guides, practice problems, reference materials, practice exams, textbook help and tutor support.
1200 Physics Lecture 2 - F2011 Current and Current density Resistivity and Resistance Power dissipation Capacitance Calculating capacitance Energy storage 1 Current and Current Density Resistivity and Resistance Ohms Law Power dissipation 2 Electric Current Charge flow is produced when an electric field is applied to charges. Positive charges flow in the direction of the electric field, negative charges move opposite to the field. E Current is defined as the rate of flow of charge: vd dq i dt Current flows in the direction that positive charge moves (and opposite to the flow of negative charge.) Current always flows from high potential to low, in the direction of the field. 3 Current Density: J Current density: The rate of current flow per unit area through a cross section to the flow. conductor +q i i J or i J dA A area J nqvdrift vdrift drift velocity n carrier density q charge per particle vA J (Current is the flux of current density) 4 Kirchhoffs Junction Rule Because electric charge is conserved, the current through any closed surface must always add up to the change of charge enclosed. At any point in an electrical circuit where charge density is not changing in time, the sum of currents flowing towards that point is equal to the sum of currents flowing away from that point. I2 dQencl J dA dt J dA 0 in steady state. P2F09 I1 wires I3 5 5 I1=I2+I3 iClicker Question 3.1 Across which line above is the current the greatest? A=aa B=bb C=cc D=They are the same. E. None of the above. I am a maverick. 6 iClicker Question 3.2 Through which line above is the current density the greatest? A=aa B=bb D=They are the same. E. N. o. t. A. (maverick) 7 Resistivity Application of an electric field causes charges to accelerate. Charges scatter off of imperfections in the material through which they move, leading to a drift velocity, which is proportional to the field. vdrift E The resistivity is the scaling factor between applied field and current density. J E resistivity 8 iClicker Question 3.3 Across which line above is the electric field the greatest? A=aa B=bb D=They are the same E. NotA(Mav) 9 Resistance* and resistivity Resistance, R, is a property of a device, for example, a wire. It depends on shape. Resistivity, , is a property of the material. L R A for a uniform wire with cross section A * is futile and length L 10 Resistance and Ohms Law V=iR When R is a constant, then this is known as Ohms Law If R varies with voltage, Ohms Law is not obeyed by that material under those conditions. Ohms Law does not hold for light bulb filaments, diodes, transistors 11 iClicker Question 3.4 A wire 100 m long and 1 mm in diameter has resistance of 1000 . What is the resistance of a wire of the same material that is 1000 m long and 0.5 mm in diameter? a) 40,000 b) 20,000 c) 1000 d) 250 e.) Mav 12 Resistivity of Metals Resistivity depends on material parameters: Most Important: The density of electrons that can move easily through the material. (~chemical valence and structure) More electrons=lower resistivity. Also important: The ease with which the most mobile electrons move through a material (structure and temperature). For many metals, resistivity increases with temperature due to increased scattering. 0 0 (T T0 ) 13 Power Dissipation The rate at which work can be done by charge flowing in a circuit can be deduced from conservation of energy. dU dqV iVdt dU Power: P iV dt V2 Resistive dissipation: P i 2 R R 14 iClicker Question 3.5 A current of 2 A flows through a resistance of 5 ohms. What is the power dissipated in the resistor? A)2 W B)5W C)10W 2 D)20W Pi R E) huh? 15 Electric Energy Storage Capacitors 16 What Is a Capacitor? A device that stores charge when a potential difference is applied The ratio of charge stored to potential difference maintained is the capacitance of object V+ q(Coulomb) the C(Farad) V (Volt) -q q is the magnitude of the charge on one plate 17 V +q Its worksheet time! Do section 1 of your worksheet. 18 iClicker Question 3.6 S1 A VB A capacitor and light bulb are wired in series so that charge flowing into the capacitor must flow through the light bulb. What happens to the brightness of the light bulb after switch S1 is closed powering the circuit? A)It lights briefly. B)It lights and stays on. C)Nothing. It remains off. 19 It lights while current flows to charge the capacitor, then stops when the capacitor is charged. iClicker Question 3.7a S1 A capacitor and light bulb are wired in series so that charge flowing into the capacitor must flow through the light bulb. A VB v What happens to the potential across the capacitor when switch 1 is closed? A)It jumps up briefly, then decays. B)It is zero. C)It remains constant. D)It grows to a constant value. Once the capacitor is charged, the potential across it is is VB. 20 iClicker Question 3.7b If S1 is held in position A for some time, the potential across the capacitor becomes constant. What happens to the potential across the capacitor when S1 is switched to position B? A)It decays to zero slowly. B)It is zero. C)It remains constant. D)It decays to zero immediately. 21 A S1 B VB Charge leaves the capacitor by flowing through the bulb. The RC Time constant We can write a simple relationship between current and voltage as a capacitor discharges through a resistor. Combine v iR and q Cv dq dv i C dt dt dv dt dv v RC dt RC v v(t ) V0e t / RC 22 Worksheet Question 3.8a If S1 is held in position A for some time, the potential across the capacitor becomes constant. What happens to the brightness of the bulb S1 is switched to position B? A)It decays to zero slowly. B)It is zero. C)It remains constant. D)It decays to zero immediately. 23 A S1 B VB Charge leaves the capacitor by flowing through the bulb. Calculating Capacitance: Parallel Plate C 1) Given a charge, find the electric field between the two capacitor plates. 2) Find the potential difference by integrating the field. Consider a pair of plates with charge density , and area A, separated by distance d . + + + + + + + - C Q /V ; E from Gauss' law 0 V Ed from V=- E ds V Q A A d Qd C 0 0 0 A d 24 iClicker Question 3.9 A parallel plate capacitor has two square plates of side length d, separated by distance b. The capacitance is C0. What would the capacitance of a similar capacitor be if the side length were increased to 2d and the distance were increased to 2b? A d2 a) 8C0 C1 d b b) 2C0 4d 2 c) C0/2 C2 2C1 2b d) C0/8 e) There is not enough information to solve for the new capacitance. 25 Capacitance: Spherical capacitor Einside S n q 4 o r 2 dr V Edr cos180 4 o r 2 b q 1 q 1 1 r 4 o b 4 o a b q q ab C 4 o q 1 1 V ba 4 o a b a q a 26 Capacitance of our Van de Graaf Sphere C 4 0 R and for our Van de Graaf R~0.15m, so C 17 pF so for 100000 V, the charge stored is 2 10-6 Coulombs 27 Capacitors in Parallel V is the same for each capacitor q1 = C1V q2 = C2V Total charge = q = q1 + q2 q (C1 C2 )V C V V C C1 C2 28 Capacitors in Series q is the same q V1 C1 q V2 C2 q q V V1 V2 C1 C2 Another result: V1 C2 V2 C1 V 1 1 1 q C C1 C2 29 Capacitors Store Energy U qV 1 2 or, since 1 2 2 q CV 2 q U CV 2C 30 iClicker Question 3.10 A certain capacitor stores 1J of energy when 100 V is applied across it. How much energy is stored if the voltage is increased to 200 V? A) J D) 2 J B) J E) 4 J C) 1J 31 Energy is stored in the Electric Field! The energy in a capacitor is stored in the electric field between the plates. Ad is the volume between the plates, so 2 1 u 2 0E is the energy per volume in the electric field between the plates. This result is true for all electric fields. 32
Find millions of documents on Course Hero - Study Guides, Lecture Notes, Reference Materials, Practice Exams and more. Course Hero has millions of course specific materials providing students with the best way to expand their education.

Below is a small sample set of documents:

Rensselaer - PHYS - 1200
Physics 1200Lecture 4 Resistive CircuitsConcepts: Electromotive force and potential Series and parallel circuits Loop and junction rules RC time constantP2S11 1iClicker question 4.012 1 X 3465YZConsider the circuit on your worksheets and on the
Rensselaer - PHYS - 1200
Physics 1200Lecture 5 Magnetic forces Creating magnetic fieldsPhysics 2 - Persans - S20111Some observations Certain chunks of metal exert force on one another even in the absence of net charge. These chunks align with respect to each other. We will a
Rensselaer - PHYS - 1200
Physics 1200Lecture 06Faradays Law and LenzLaw Inductance Transformers!** Roll out!Spring 2011 1iClicker Question 6.01 We know that a current in a wire creates a magnetic field. We also know that a magnetic field induces a force on a moving charge o
Rensselaer - PHYS - 1200
Physics 2 S 2011 Lecture 07RC, RL, LC and RLC circuits Harmonic signals AC devices1Capacitors and inductors in circuitsdi d 2q Emf L L L 2 dt dt dq Emf R iR R dt 1 qC EmfC idt C C Write Emf loop equations and/or junction equations using current or ch
Rensselaer - PHYS - 1200
Rensselaer - PHYS - 1200
Rensselaer - PHYS - 1200
Coastal Carolina - ENGLISH - 1100
Dickson Bridger English 1200, 9 Dr. Schlobin December 1, 2009 CANCER RESISTANT Cancer is a term used for diseases in which abnormal cells divide without control and are able to invade other tissues. Cancer cells spread to parts of the body through the blo
Moraine Valley Community College - BUSINESS - 143
14-1Chapter 14Managerial Accounting Concepts and PrinciplesMcGraw-Hill/Irwin The McGraw-Hill Companies, Inc., 200714-2C1Nature of Managerial AccountingFinancial Accounting1. Users anddecision makers I nvestors, creditors and other external users
University of Ottawa - ECON - 6120
ECON 3808 Economies in TransitionInstructor: Crina Viju TA: Sara RoseDefining an economy Economic system: set of mechanisms guiding resource allocation Decision-making structure; Information and coordination mechanisms; Property rights; Incentives. E
University of Ottawa - ECON - 6120
The Social History of Alcohol HIST 3109A , 3109T Course OutlineLectures Instructor Office E-mail Office hours Tuesdays, 6:05-8:55 PM Professor Rod Phillips Paterson Hall, Room 409 roderick_phillips@carleton.ca Mondays 10:00-11:30AM, or by appointmentFal
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Lecture2:Questions (1)GreeceandRomesponsoredviticultureinSpain,France,andPortugal?(T/F) (2)Whenisitestimatedbyhistoriansthatwine/beerwerediscovered? (3)Howhavehistoriansestimatedthistimeperiod? (4)Theoldestknownwinevesselcanbedatedtowhatcentury? (5)Howwas
University of Ottawa - ECON - 6120
History of Alcohol Lecture 3 Period 1000 1500s There was alsways a distinction between wine/beer and spirits Spirits didnt have the same associations with religion or health (no tradition) Monasteries had the privilege to distil Privilege means private
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Lecture 5Distilled Beverages Heat to remove water and leave alcohol Vapour gets catched and drained into liquid form leaving high alcohol content (rectification) Alchemists were the first trying to turn base metals into gold Largely confined to monasteri
University of Ottawa - ECON - 6120
History of Alcohol Lecture 6America 17th century (1600s): Distilling and viticulture spread towards the west Americans had a hostile outlook on alcohol, much different from Europe Puritans were Anglicans (members of the church of England) who didnt app
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Take Home QUIZ #2 E3050A To be handed in to my mailbox no later then December 22, 2010 All questions are worth 10 marks each The Quiz is worth 20% of your Final Mark. 1. Vincent Van Gogh sold only one painting during his lifetime, for about \$30. A sunflow
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 9 Empirical appraisal of the CAPM and APT1. The following table contains ten years of excess return data for the ordinary shares of ABC plc and the market portfolio. Discuss how co
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 10 Present value relationships and price variability1. Suppose that the relationship between the rate of interest, dividends and an asset price is given by: dt+i+1 pt+i+1 pt+i rt+i
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 1 Asset markets and asset prices1. Consider the following foreign exchange rates: 1 = e 2 1 = \$1.5 \$1 = e 1 Examine the opportunity for arbitrage prots if such prices were observed
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 2 Asset market microstructure1. Distinguish between order-driven and quote-driven asset markets. Discuss their relative strengths and weaknesses.2. To what extent is there a trade
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 3 Predictability of prices and market efciency1. In the following table the probabilities of an assets payoffs are given, according to whether the information available to the inve
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 4 Decision making under uncertainty1. Consider an investor who makes decisions according to a mean-variance objective. (a) Sketch indifference curves for the investor (with expecte
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 5 Portfolio selection: the mean-variance model1. An investor uses the mean-variance criterion for selecting a portfolio of two risky assets. Asset 1 has an expected return of 20% a
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 6 The capital asset pricing model1. The following information is provided for a stock market: j 6.6% 9.8% 12.2% j 0.4 1.2 1.8Asset 1 Asset 2 Asset 3Notation: j = expected rate of
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYSolution Guide to Exercises for Chapter 4 Decision making under uncertainty1. Consider an investor who makes decisions according to a mean-variance objective. (a) Sketch indifference curves for the inve
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYSolution Guide to Exercises for Chapter 6 The capital asset pricing model1. The following information is provided for a stock market: j 6.6% 9.8% 12.2% j 0.4 1.2 1.8Asset 1 Asset 2 Asset 3Notation: j
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 7 Arbitrage1. What is the arbitrage equilibrium price of asset C in the example below? (Explain) Asset A State 1 State 2 Price 9 4 5 Asset B 0 8 4 Asset C 12 6 ?2. Use the informa
University of Ottawa - ECON - 6120
T HE E CONOMICS OF F INANCIAL M ARKETSR. E. BAILEYExercises for Chapter 8 Factor models and the arbitrage pricing theory1. The following information is provided for a stock market in which asset returns respond to two factors: Asset A B r0 bj 1 1.2 0.8
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Carleton University Department of Economics ECON 3050 A Int roduction to Financial Economics Instructor: Peter Wrage Fall 2010 E-mail: peter_wrage@carleton.ca Office: A-802 Loeb Office Hours: Mondays, 4:305:30 p.m. Telephone: 613-520-2600 x 6668 Teaching
University of Ottawa - ECON - 6120
The Economics of Financial MarketsRoy E. Bailey Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, So Paulo Cambridge University Press The Edinburgh Building, Cambridge , UK Published in the United States of America by Cambridge University Pr
University of Ottawa - ECON - 6120
ECON 3050A Introduction To Financial Economics Lecture 1 Asset Markets And Asset Prices We will consider how asset prices are determine and, consequently their rates of return Central to asset price determination is the process of arbitrage, a process tha
University of Ottawa - ECON - 6120
ECON 3050A Introduction to Financial Economics Lecture 2 The Asset Market Microstructure We had previously argued that the market price of an asset was determined by investors willing to hold the existing stock of an asset in total i.e. its total supply.
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Lecture200:0023:59 ECON3050A IntroductiontoFinancialEconomics Lecture2 TheAssetMarketMicrostructure Wehadpreviouslyarguedthatthemarketpriceofanassetwasdeterminedbyinvestorswillingtoholdthe existingstockofanassetintotali.e.itstotalsupply. Analternativeap
University of Ottawa - ECON - 6120
EC371-mock 1 UNIVERSITY OF ESSEXFINAL YEAR EXAMINATIONS 2008EC371-3-AU ECONOMIC ANALYSIS OF ASSET PRICESTime allowed: 2 hours.Section A: Answer any TEN questions Section A contains TWELVE questions. Section B: Answer ONE question. Section B contains T
University of Ottawa - ECON - 6120
EC371-mock 1EC371 Economic Analysis of Asset Prices Mock Exam Answer Guidelines Section A Answer TEN questions.1. An asset will pay a dividend of \$11 at date t + 1 at which date its market value will be \$77 (with certainty). The risk-free interest rate
University of Ottawa - ECON - 6120
Preparing For The Final Exam For E 3050A The Final Exam will cover Chapters 5 to 10 inclusive. You should focus on the interpretations of the derivations, the assumptions, the results and implications similar to the Midterm. You should also be able to do
University of Ottawa - ECON - 6120
QuestionsforChapt.1THEECONOMICSOFFINANCIALMARKETSR.E.BAILEYExercisesforChapter1Assetmarketsandassetprices 1.Considerthefollowingforeignexchangerates:1=e21=\$1.5\$1=e1Examinetheopportunityforarbitrage profitsifsuchpriceswereobserved.Whatwouldyoupredictwould
University of Ottawa - ECON - 6120
ECON 3808 The economics of transitionThe Socialist SystemOutline Marxism System prototypes Common attributes before revolution Power ideology Centrally planned economy Criticism Costs and benefits of central planning Failures of market systemMarxism
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
ECON 3808 ECONOMICS OF TRANSITION Course outline Winter 2011Instructor: Dr. Crina Viju Email: crina_viju@carleton.ca Phone: 520-2600x8440 Office: DT 1303 Classes: Mondays, 11:35 AM 2:25 PM, Room: Tory Building 340 Office hours: Thursdays: 2:30 PM - 4:30
University of Ottawa - ECON - 6120
A Ss,9,1 r r'!r tl1 -52 l','t'l-ronaE ca'r31o6 A-hi llG,'tts*w^ ' i- 3o =cfw_et,o vl4fiYv'L&lt;'o ! relvr.,;Fct-*)IIo()(rJJA(Jtllla-(t-cfw_)JYrx = ! i 4 cfw_ ) l &quot;',o.-11vI.rv=\1. IiJIa(, t - i r.) &quot; , Yr = = I 'Zd,tl+1&quot;= t(
University of Ottawa - ECON - 6120
CARLETON UNIVERSITY DEPARTMENT OF ECONOMICS ECON 3706 A: ASSIGNMENT 1Please read the following instructions carefully: 1. Read the questions carefully and show all your work clearly. 2. The assignment must be written in pen only. If you write in pencil t
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
University of Ottawa - ECON - 6120
Carleton University Department of Economics Economics 3706 A APPLIED ECONOMETRICS Winter 2011INSTRUCTOR: Dr. Gubhinder Kundhi OFFICE: D 886 Loeb Building PHONE: 613 520 2600 x 3759 EMAIL: gkundhi@connect.carleton.ca OFFICE HOURS: Mondays, 11:35am 12.35pm
Seoul National - ENGLISH - 200412027
Elementary Composition (1) September 9, 2008 07124314 JANG YEON JUMy breakfast habitsUsually, I skip my breakfast. First, I dont have enough time to eat breakfast. I think I need more sleeping than eating in the morning. If I have extra time in the morn
Seoul National - ENGLISH - 200412027
Elementary Composition (1) September 16, 2008 07124314 JANG YEON JUSomething ValuableMany years ago, when I was elementary school student, I really want to have a new wallet. At that time, I thought best valuable thing is the wallet and when I was high
Seoul National - ENGLISH - 200412027
Elementary Composition (1) September 23, 2008 07124314 JANG YEON JUDo exercise, and you can be healthExercise is an excellent method to improve your overall health. First, obesity is source of all disease. Many people are worrying about their fatness bu
Seoul National - ENGLISH - 200412027
Elementary Composition (1) October 14, 2008 07124314 JANG YEON JUDo exercise, and you can be healthyExercise is an excellent method to improve your overall health. First, I think obesity is a root of all diseases. Many people are worrying about their fa
Seoul National - ENGLISH - 200412027
E lementary Composition (1) September 30, 2008 07124314 JANG YEON JU Where is the special restaurant? Do you have a fun eating out? Nowadays, because some people who dont stay home at noon cant go their home to eat lunch because of many reasons and many p
Seoul National - ENGLISH - 200412027
Elementary Composition (1) October 7, 2008 07124314 JANG YEON JUMy best day, it was worst for a whileI have a special memory about my day that it was changed from worst to best. A year ago, I studied hard all night to prepare mid-term. The major subject
Seoul National - ENGLISH - 200412027
Elementary Composition (1) October 7, 2008 07124314 JANG YEON JUMy best day, it was the worst for a whileI have a special memory about a day that was changed from the worst to the best. A year ago, I studied hard all night to prepare for my mid-term. Th
Seoul National - ENGLISH - 200412027
E lementary Composition (1) October 14, 2008 07124314 JANG YEON JUGiraffe, an animal in imagination to the Oriental peopleNowadays we can easily see many giraffes in a zoo and there is much information about t hem in variety books. Also, the dictionary
Seoul National - ENGLISH - 200412027
E lementary Composition (1) October 21, 2008 07124314 JANG YEON JU Censorship is needed properly A dictionary defines censorship as a restraint or control. So, many people think thecensorship has only bad images. However, censorship has many positive asp
Seoul National - ENGLISH - 200412027
Elementary Composition (1) November 18, 2008 07124314 YEON JU JANGOne picture is worth a thousand wordsThe saying One picture is worth a thousand words. is very common true and teaches us the important of experience. This saying means first seeing is be