Power in Resistive Electric Circuits
|
|
- Mitchell Dalton
- 6 years ago
- Views:
Transcription
1 Chapter Solutions Resistance and Resistivity Description: Short conceptual problem on resistance and resistivity of an ohmic conductor of different sizes at the same temperature. Based on Young/Geller Conceptual Analysis 19.1 Part A At the same temperature, two wires made of pure copper have different resistances. The same voltage is applied at the ends of each wire. The wires may differ in Hint A.1 Differences in resistivity The resistivity of a metallic conductor, such as copper, nearly always increases with increasing temperature. Hint A. Resistance of an ohmic conductor For an ohmic conductor, that is, a conductor such as copper that obeys Ohm's law, the resistance R is proportional to the length L and inversely proportional to the cross-sectional area A. That is, where is the resistivity of the material. Note that is a characteristic of the specific material and may vary with temperature. Hint A.3 Ohm's law Ohm's law tells us that the potential difference V between the ends of a conductor is equal to the product of the current I through the conductor and the conductor's resistance R, Check all that apply. length. cross-sectional area. resistivity. amount of electric current passing through them.,. Power in Resistive Electric Circuits Description: In a one-loop resistive circuit, calculate the power dissipated in the resistor and in the battery (via its internal resistance). Show various alternative sets of variables that can be used to express the power. (version for algebra-based courses) Learning Goal: To understand how to compute power dissipation in a resistive circuit.
2 The circuit in the diagram consists of a battery with EMF E, a resistor with resistance R, an ammeter, and a voltmeter. The voltmeter and the ammeter (labeled V and A, respectively) can be considered ideal; that is, their resistances are infinity and zero, respectively. The current in the resistor is I, and the voltage across it is V. The internal resistance of the battery r int is not zero. Part A What is the ammeter reading I? Express your answer in terms of E, R, and r int. Note that the resistances of the ammeter and voltmeter do not appear in the answer. That is because these two circuit elements are "ideal." The voltmeter has infinite resistance, so no current flows through it. The ammeter has zero resistance, so there is no voltage drop as current flows through it. Part B What is the voltmeter reading V? Hint B.1 Find the potential difference across the internal resistance What is the change in potential V int across the battery? Express your answer in terms of current I and the resistance R. Substitute for I in terms of the variables asked for. Also add in any other contributions to the voltage measured by the voltmeter, with correct signs. Express your answer in terms of E, R, and r int.
3 In the following parts, you will express the power dissipated in the resistor of resistance R using three different sets of variables. Part C What is the power Pr dissipated in the resistor? Express your answer in terms of I and V. Part D Again, what is the power Pr dissipated in the resistor? This time, express your answer in terms of one or more of the following variables: I, r int, and R. Part E For the third time, what is the power Prdissipated in the resistor? Express your answer in terms of one or more of the following variables: E, r int, and R. Power Dissipation in Resistive Circuit Conceptual Question Description: Short conceptual problem related to power dissipation in resistive circuits. A single resistor is wired to a battery as shown in the diagram below.
4 Define the total power dissipated by this circuit as P. Now, a second identical resistor is wired in series with the first resistor as shown in the second diagram to the left. Part A What is the power, in terms of P, dissipated by this circuit? Hint A.1 How to find the power dissipated by a circuit The power dissipated by a circuit (or by an element in a circuit) is defined by the relation
5 . If the circuit consists of resistors, we can combine this relation with Ohm's law, to yield two alternate versions of the power formula:, and. Because several circuit parameters can be changing simultaneously, it is easiest to use the formula in which only one of the terms is changing for your situation. This makes it much easier to determine the power dissipated in a resistive circuit. Hint A. Effect of adding a resistor in series Adding a resistor in series affects both the total resistance and total current in a circuit. Combining an understanding of these changes with the appropriate version of the power formula should allow you to answer this question. Express your answer in terms of. The second resistor is now removed from the circuit and rewired in parallel with the original resistor as shown in the schematic to the left
6 Part B What is the power, in terms of, dissipated by this circuit? Hint B.1 How to find the power dissipated by a circuit The power dissipated by a circuit (or by an element in a circuit) is defined by the relation. If the circuit consists of resistors, we can combine this relation with Ohm's law, to yield two alternate versions of the power formula:, and. Because several circuit parameters can be changing simultaneously, it is easiest to use the formula in which only one of the terms is changing for your situation. This makes it much easier to determine the power dissipated in a resistive circuit. Hint B. Effect of adding a resistor in parallel Adding a resistor in parallel affects both the total resistance and current in a circuit. Combining an understanding of these changes with the appropriate version of the power formula should allow you to answer this question. Express your answer in terms of. ± Resistance of a Heater Description: ± Includes Math Remediation. Numerical problem on current and resistance of a heater, and finding how long it takes to heat a typical room. A 1500-W heater is designed to be plugged into a 10-V outlet. Part A What current will flow through the heating coil when the heater is plugged in? Hint A.1 Setting it up A heater can be modeled as a resistor. Hint A. Power Write an expression for P, the power dissipated through a resistor, in terms of V, the voltage across the resistor, and I, the current through the resistor.
7 Hint A.3 Finishing up Give an analytic expression for I in terms of V and P, the power. Now plug in the values for P and V given in the problem. Express your answer for the current numerically, to three significant figures. A Note that watts/volts has the correct units: Since and then,. Part B What is R, the resistance of the heater? Hint B.1 Which equation to use Now that you know I, you can easily find R using the relation VIR. Express your answer numerically, to three significant figures. ohms Part C How long does it take to raise the temperature of the air in a good-sized living room by? Note that the specific heat of air is 1006 Hint C.1 Mass of the air and the density of air is. What is the mass of air contained within the room? Express your answer numerically, to three significant figures.
8 kg Hint C. How many joules What is the energy required to heat the air in the room? Hint C..1 Formula for the energy required to heat an object The formula for the energy Q required to heat an object is where m is the mass of the object, c is its heat capacity and delta T is the temperature difference through which it is heated. Express your answer numerically in kilojoules, to three significant figures. Express your answer numerically in minutes, to three significant figures. kj minutes Actually, the heat capacity of the walls and other material in the room will generally exceed that of the air by several times, so an hour is a more reasonable time to heat the room by this much. PROBLEMS P.1. Prepare: We will find the total charge that flows through the hair dryer and then divide it by the electron charge to find the number of electrons. Solve: Equation. is Q I t. The amount of charge delivered is 60 s Q (10.0 A) 5.0 min 3000 C 1 min The number of electrons that flow through the hair dryer is Q 3000 C N e C Assess: This is an enormous amount of charge and is typical of such devices. P.4. Reason: The relationship between current, charge, and time is I Q / t. 1 4 Solve: The current is I Q / t C / ( s) 1.8 A Assess: We expect a small current due to very small flow of charge. P.6. Prepare: Electric current, charge, and time are related by I Q/ t. 4 4 Solve: The current during the lightning strike is I Q/ t.5 C/(.0 10 s) A. Assess: As expected, this is a large amount of current.
9 P.7. Prepare: Current is defined in terms of the amount of charge Q passing through a cross section of the wire in a time interval t: I Q/ t. We are given that Solve: 6 t 40 s s and Q (1 0 13)( C) (0 87)( C) 5 10 C. Q I t s C 6 13 A Assess: 13 A is a fairly large current, but that is because capacitors discharge very quickly when the plates are connected with a wire. In the next chapter you will learn more specifically how the current decays in a discharging capacitor; it isn t at a constant rate or in a linear fashion. But since all we re asked for in this problem is the average current, we are already equipped to solve the problem. P.15. Prepare: The emf is defined as the work done per unit charge by the charge escalator or the battery, so we will use Equation.4. Solve: W q Assess: An emf of 1 V is reasonable for a battery J C chem P.18. Reason: The total potential difference is related to the potential difference for one cell by V NV. total cell Solve: The number of cells needed to generate a total potential difference of 350 V is N Vtotal / Vcell 350 V / (0.110 V) 3180 cells. Assess: Since the potential difference per cell is small, we expect a large number of cells. P.1. Prepare: The resistance of a wire may be determined by R L/ Aand the volume of the wire may be determined by V LA. We can use the expression for the volume to eliminate the area A in the expression for the resistivity and obtain R L/ A L/( V/ L) L / V. This expression informs us that the resistance of a wire varies as the square of the length if the volume remains constant. Solve: Since the length has doubled and the resistance varies as the length squared, the resistance of the stretched wire will be four times that of the unstretched wire. R stretched Assess: This is a reasonable resistance for wire. unstretched 1 V 4R 4(0.010 ) P.. Prepare: Resistivity is related to resistance, length, and cross-sectional area by R L / A, and the area is related to the width and thickness of the leaf by A WT. Solve: Combining these two expressions and solving for the resistivity, we obtain RA L RWT L 6 4 / / (.0 10 Ω)(.5 10 m)(.0 10 m) / (0.0 m) 50 Ω m Assess: This value for the resistivity is the same order of magnitude as other organic materials listed in Table.1. P.4. Prepare: Resistance, current, and electric potential difference are related by Ohm s law R V / I. Resistance, resistivity, length, and cross-sectional area are related by R L / A. Solve: Combining these two expressions and solving for the length of the wire obtain:
10 5 AV r V ( m) (1 V) L 8.7 m 8 I I (4.0A)( Ω m) Assess: This is a reasonable length and can be sewn into a vest. P.7. Prepare: The potential difference between the ends of a copper wire that carries a current can be obtained from Equation.6, I V/ R, and Equation.8, R L/. A The resistivity of copper from Table.1 8 is m. Solve: 8 L (3.0 A)( m)(0.0 m) V IR I 13 mv 3 A ( m) Assess: Because copper s resistivity is small, a potential difference of 13 mv across a 1.0 mm diameter and 0-cm long wire is reasonable. P.8. Prepare: Resistance is related to resistivity, length, and cross-sectional area by R L / A. An electrical worker could have palms that are 10 cm by 1 cm or m Solve: The resistance is R L / A ( Ω m)( m) / (1. 10 m ) Ω Assess: This built-in safety factor is a good thing and a reasonable value. P.40. Prepare: The relationships needed for this problem are P IV, P U / t and Q I t. Solve: (a) The power is P IV 360 W. (b) The total energy is U P t 0.36 J. 4 (c) The total charge that flows is Q I t C. Assess: Given the electric potential, current, and time pulse, these are reasonable values for the power, total energy, and total charge. P.41. Prepare: The dimensions of current times time (the rating printed on the battery) are not yet the dimensions of energy until we multiply by the dimensions of voltage. That is, in SI units, A s C, not J. However, if we multiply both sides by V then the result is an energy unit: A s V J. The upshot of this is that the battery rating ma h doesn t tell us the energy capacity unless we also know the voltage of the battery. But we do know the voltage of the battery, so we proceed. Solve: 1A 3600 s (450 ma h)(9 V) A s V J 15,000 J 1000 ma 1h Assess: This is a reasonable amount of energy. Fatter batteries hold more chemicals and therefore more chemical potential energy, so a D-cell would have a higher ma h rating than a AA-cell (both at 1.5 V). The 9 V battery likely has six 1.5 V cells connected in series inside. P.46. Prepare: This is an integrated problem and we will need to use information from previous chapters such as Equation 1.1, Q Mc T, to get the energy Q, and the equation for power, P Q/ t, along with the equation for electrical power, P ( V ) / R (assuming the hot dogs are ohmic). We ll solve the middle equation for t, insert P from the last equation and Q (which is energy, not charge) from the first. Known V 10 V
11 R 150 M kg T 80 C 0 C 60 C 60 K c 500 J/(kg K) (from Table 1.4) Find t Solve: Q Mc T (0 060 kg)(500 J/(kg K))(60 K) t 94 s P ( V) / R (10 V) /(150 ) Assess: The answer is just over one and a half minutes. This is not as fast as a modern microwave, but it was considered pretty quick before microwave ovens came along. Hot dogs cooked this way do not have a nice grilled look or flavor; they don t smell as good as grilled hot dogs either. But kids will eat anything. It is especially in the integrated problems that we are likely to run into different uses of the same symbol. Recently we ve been using Q as charge, but in this problem it is energy. The units deserve some attention. The kg and K cancel in the numerator. We re left with J / V. Further, V/A and V J/C. J J V J V J C C s V V A A V A J A P.55. Prepare: We assume the extension cord is ohmic so we can use V IR. We also use R L/. A We are given L 50 ft 15 m, I 10 A, and A r d 8 look up the resistivity of copper in Table.1: Cu m. Solve: Combine the two equations. 6 ( /) (1 3 mm/) m. We also 8 L ( m)(15 m) V IR I (10 A) 1 9 V 6 A m Assess: 1.9 V is less than percent of 10 V, but in some situations it can be important. The longer the extension cord the greater the resistances (if the diameter stays the same); the greater the voltage drop across the cord, the more power is dissipated as thermal energy in the cord. If your extension cord gets hot to the touch, then you are dissipating too much power in the cord. Get a shorter or fatter extension cord. If you buy a long extension cord, make sure it has a low-gauge wire (large diameter) so the resistance will be low. P.61. Prepare: Since we are asked for L and given and A (indirectly), we figure we want to solve the following for L: R L/ A. We will need to solve for R in P ( V ) / R and insert it into the equation for L. Known V 10 V P 100 W m A m Find L Solve: A r ( d/) (0 035 mm/) m.
12 RA V A L P 100 W m ( ) 10 (10 V) m 0 8 m 8 cm 7 Assess: The data and result match reasonably closely those in Example.6, and this comforts us. The wattages of the bulbs aren t the same, and the given diameters are slightly different, so we don t expect a perfect match, but our answer is about within a factor of two of the answer in the example for a similar situation. The units deserve some attention. One of the m s cancels. Split the V apart, and for one of them use V J/C. Also apply W J/s and A C/s. At the end we will use V A. J V C VV m m V s m V m m W J/s C A P.65. Prepare: Rewrite I Q/ t as Q I t for a constant current that is straightforward. If I varies, as in our problem, Q would be the area under an I vs. t graph, which we can figure out in sections. In part (b) we ll use P I R, and, since energy power time, P t I R t, in sections. We are given that R 1 0. Solve: (a) Between t 0sand t s there is no area under the graph. Between t s and t 5sthe area is ( 5 A)(3 0 s) 7 5 A s 7 5 C. Between t 5sand t 10 s the area is (1 5 A)(5 0 s) 6 5 A s 6 5 C. The total area under the graph is 7 5 C 6 5 C C 14 C. (b) Between Between Between t 0sand t s there is no current so I R t 0 J. t s and t 5 s, t 5sand t 10 s, I R t ( 5 A) (1 0 )(3 0 s) J. I R t (1 5 A) (1 0 )(5 0 s) 7 81J. The energy dissipated is 0 J J 7 81J 6 6 J 7 J. Assess: These results both seem reasonable, not obviously out of the ballpark. Calculus would allow one to find the total Q for a smoothly varying current, as it allows one to find the area under a curve. P.67. Prepare: We ll use Ohm s law to calculate the current in each case. Solve: (a) V 10 V I 0 4 ma 5 R 5 10 This does not exceed the maximum safe current of 5 ma, so it is not dangerous. (b) V 10 V I 10 ma R 1000 This exceeds the maximum safe current and is dangerous. Assess: The warnings against using electrical equipment while wet (in the shower, for example) make a lot of sense. Your resistance from one fingertip to another on the other hand is much larger than the resistance between fingertips on the same hand, so you might get a good shock touching the terminals with the same hand. The good thing is that the current wouldn t go through your heart in this case. P.68. Prepare: The resistance of a wire is related to its resistivity, length, and cross-sectional area by R L/. A The area of a wire is related to its diameter by A d /4. The potential drop across a resistor is related to the resistance of the resistor and the current through the resistor by V IR. The power dissipated is related to potential difference, current, and resistance by P VI I R V / R. Solve: (a) The resistance between the hands is R L A L d L d 3 / /( /4) 4 /( ) 4(5.0 m)(1.6 m)/( (0.10 m) ) (b) The potential difference across a resistor of this size when there is a current of 100 ma is
13 V IR 3 (0.10 A)( ) 100 V Assess: This result tells us that a potential difference of 100 V can be lethal. This should give you new respect for the potential difference at all of your electrical outlets.
Chapter 22: Current and Resistance Solutions
Chapter 22: Current and esistance Solutions Questions: 4, 7, 17, 21 Exercises & Problems: 1, 16, 22, 28, 36, 38, 51, 53, 55 Q22.4: A lightbulb is connected to a battery by two copper wires of equal lengths
More informationCapacitance. A different kind of capacitor: Work must be done to charge a capacitor. Capacitors in circuits. Capacitor connected to a battery
Capacitance The ratio C = Q/V is a conductor s self capacitance Units of capacitance: Coulomb/Volt = Farad A capacitor is made of two conductors with equal but opposite charge Capacitance depends on shape
More informationphysics 4/7/2016 Chapter 31 Lecture Chapter 31 Fundamentals of Circuits Chapter 31 Preview a strategic approach THIRD EDITION
Chapter 31 Lecture physics FOR SCIENTISTS AND ENGINEERS a strategic approach THIRD EDITION randall d. knight Chapter 31 Fundamentals of Circuits Chapter Goal: To understand the fundamental physical principles
More informationElectric Currents and Circuits
Electric Currents and Circuits Producing Electric Current Electric Current flow of charged particles Need a potential difference to occur Conventional Current- flow of positive charges flowing from positive
More informationChapter 21 Electric Current and Direct- Current Circuits
Chapter 21 Electric Current and Direct- Current Circuits Units of Chapter 21 Electric Current Resistance and Ohm s Law Energy and Power in Electric Circuits Resistors in Series and Parallel Kirchhoff s
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 informationCircuits. 1. The Schematic
+ ircuits 1. The Schematic 2. Power in circuits 3. The Battery 1. eal Battery vs. Ideal Battery 4. Basic ircuit nalysis 1. oltage Drop 2. Kirchoff s Junction Law 3. Series & Parallel 5. Measurement Tools
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 2. Engr228 Circuit Analysis. Dr Curtis Nelson
Chapter 2 Engr228 Circuit Analysis Dr Curtis Nelson Chapter 2 Objectives Understand symbols and behavior of the following circuit elements: Independent voltage and current sources; Dependent voltage and
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 informationResistivity and Temperature Coefficients (at 20 C)
Homework # 4 Resistivity and Temperature Coefficients (at 0 C) Substance Resistivity, Temperature ( m) Coefficient, (C ) - Conductors Silver.59 x 0-0.006 Copper.6 x 0-0.006 Aluminum.65 x 0-0.0049 Tungsten
More informationELECTRIC CURRENTS D R M A R T A S T A S I A K D E P A R T M E N T O F C Y T O B I O L O G Y A N D P R O T E O M I C S
ELECTRIC CURRENTS D R M A R T A S T A S I A K D E P A R T M E N T O F C Y T O B I O L O G Y A N D P R O T E O M I C S lecture based on 2016 Pearson Education, Ltd. The Electric Battery Electric Current
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 informationEXPERIMENT 12 OHM S LAW
EXPERIMENT 12 OHM S LAW INTRODUCTION: We will study electricity as a flow of electric charge, sometimes making analogies to the flow of water through a pipe. In order for electric charge to flow a complete
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 informationELECTRICITY. Prepared by: M. S. KumarSwamy, TGT(Maths) Page
ELECTRICITY 1. Name a device that helps to maintain a potential difference across a conductor. Cell or battery 2. Define 1 volt. Express it in terms of SI unit of work and charge calculate the amount of
More informationPhysics 1214 Chapter 19: Current, Resistance, and Direct-Current Circuits
Physics 1214 Chapter 19: Current, Resistance, and Direct-Current Circuits 1 Current current: (also called electric current) is an motion of charge from one region of a conductor to another. Current When
More informationThe Digital Multimeter (DMM)
The Digital Multimeter (DMM) Since Physics 152 covers electricity and magnetism, the analysis of both DC and AC circuits is required. In the lab, you will need to measure resistance, potential (voltage),
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 informationName... Class... Date...
The power of lamps Specification references: P2.4.1 Power P2.4.2 Energy transfers in everyday appliances (part) MS 1a, 2a, 3b, 3c, 3d WS 1.2, 2.6, 3.1, 3.3 Aims In this practical, you will observe the
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 informationELECTRICITY & CIRCUITS
ELECTRICITY & CIRCUITS Reason and justice tell me there s more love for humanity in electricity and steam than in chastity and vegetarianism. Anton Chekhov LIGHTNING, PART 2 Electricity is really just
More informationPhysics 7B-1 (A/B) Professor Cebra. Winter 2010 Lecture 2. Simple Circuits. Slide 1 of 20
Physics 7B-1 (A/B) Professor Cebra Winter 2010 Lecture 2 Simple Circuits Slide 1 of 20 Conservation of Energy Density In the First lecture, we started with energy conservation. We divided by volume (making
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 cross-sectional area of the conductor changes. If a conductor has no current,
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 informationTactics Box 23.1 Using Kirchhoff's Loop Law
PH203 Chapter 23 solutions Tactics Box 231 Using Kirchhoff's Loop Law Description: Knight/Jones/Field Tactics Box 231 Using Kirchhoff s loop law is illustrated Learning Goal: To practice Tactics Box 231
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 informationTopic 5.2 Heating Effect of Electric Currents
Topic 5.2 Heating Effect of Electric Currents Kari Eloranta 2017 Jyväskylän Lyseon lukio International Baccalaureate February 14, 2017 Topic 5.2 Heating Effect of Electric Currents In subtopic 5.2 we study
More information3.14 mv ma. Objectives. Overview
Phys 3 Lab 7 Ch 0 Simple DC and RC Circuits Equipment: power supply, banana cables, circuit board, switch, 0, 70, 460, & 30, k,two multi-meters, differential voltage probe, Phys 3 experiment kits: batteries
More informationExercise Problem Correct. Correct. Heimadæmi 5. Part A. Part B. Due: 11:45pm on Thursday, February 18, 2016
Heimadæmi 5 Due: 11:45pm on Thursday, February 18, 2016 You will receive no credit for items you complete after the assignment is due. Grading Policy Exercise 26.34 In the circuit shown in the figure.
More information2/25/2014. Circuits. Properties of a Current. Conservation of Current. Definition of a Current A. I A > I B > I C B. I B > I A C. I C D. I A E.
Circuits Topics: Current Conservation of current Batteries Resistance and resistivity Simple circuits 0.1 Electromotive Force and Current Conventional current is the hypothetical flow of positive charges
More informationLABORATORY 4 ELECTRIC CIRCUITS I. Objectives
LABORATORY 4 ELECTRIC CIRCUITS I Objectives to be able to discuss potential difference and current in a circuit in terms of electric field, work per unit charge and motion of charges to understand that
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 informationA Review of Circuitry
1 A Review of Circuitry There is an attractive force between a positive and a negative charge. In order to separate these charges, a force at least equal to the attractive force must be applied to one
More informationPhysics Module Form 5 Chapter 2- Electricity GCKL 2011 CHARGE AND ELECTRIC CURRENT
2.1 CHARGE AND ELECTRIC CURRENT Van de Graaf 1. What is a Van de Graaff generator? Fill in each of the boxes the name of the part shown. A device that... and... at high voltage on its dome. dome 2. You
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 informationPhysics Module Form 5 Chapter 2- Electricity GCKL 2011 CHARGE AND ELECTRIC CURRENT
2.1 CHARGE AND ELECTRIC CURRENT Van de Graaf 1. What is a Van de Graaff generator? Fill in each of the boxes the name of the part shown. A device that produces and store electric charges at high voltage
More informationCurrent and Resistance
PHYS102 Previous Exam Problems CHAPTER 26 Current and Resistance Charge, current, and current density Ohm s law Resistance Power Resistance & temperature 1. A current of 0.300 A is passed through a lamp
More informationChapter 26 Direct-Current Circuits
Chapter 26 Direct-Current Circuits 1 Resistors in Series and Parallel In this chapter we introduce the reduction of resistor networks into an equivalent resistor R eq. We also develop a method for analyzing
More informationDirect Current Circuits. February 18, 2014 Physics for Scientists & Engineers 2, Chapter 26 1
Direct Current Circuits February 18, 2014 Physics for Scientists & Engineers 2, Chapter 26 1 Kirchhoff s Junction Rule! The sum of the currents entering a junction must equal the sum of the currents leaving
More informationElectromotive Force. The electromotive force (emf), ε, of a battery is the maximum possible voltage that the battery can provide between its terminals
Direct Current When the current in a circuit has a constant magnitude and direction, the current is called direct current Because the potential difference between the terminals of a battery is constant,
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 informationPhysics 2020 Lab 5 Intro to Circuits
Physics 2020 Lab 5 Intro to Circuits Name Section Tues Wed Thu 8am 10am 12pm 2pm 4pm Introduction In this lab, we will be using The Circuit Construction Kit (CCK). CCK is a computer simulation that allows
More informationPEP 2017 Assignment 12
of the filament?.16.. Aductile metal wire has resistance. What will be the resistance of this wire in terms of if it is stretched to three times its original length, assuming that the density and resistivity
More informationInsulators Non-metals 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 non-ohmic conductors Series and parallel connection Energy in an electric circuit X-planation 1. CONDUCTORS AND INSULATORS
More informationSuperconductors A class of materials and compounds whose resistances fall to virtually zero below a certain temperature, T C T C is called the critical temperature The graph is the same as a normal metal
More informationUnit 6 Current Electricity and Circuits
Unit 6 Current Electricity and Circuits 2 Types of Electricity Electricity that in motion. Electricity that in motion. Occurs whenever an moves through a. 2 Types of Current Electricity Electricity that
More informationPhysics 115. General Physics II. Session 24 Circuits Series and parallel R Meters Kirchoff s Rules
Physics 115 General Physics II Session 24 Circuits Series and parallel R Meters Kirchoff s Rules R. J. Wilkes Email: phy115a@u.washington.edu Home page: http://courses.washington.edu/phy115a/ 5/15/14 Phys
More informationChapter 7 Direct-Current Circuits
Chapter 7 Direct-Current Circuits 7. Introduction... 7. Electromotive Force... 7.3 Resistors in Series and in Parallel... 4 7.4 Kirchhoff s Circuit Rules... 6 7.5 Voltage-Current Measurements... 8 7.6
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 informationTOPIC 25 RESISTANCE COVERING: R = VII = 3/0.25 = 12 Q
TOPIC 25 RESISTANCE COVERING: simple measurement of resistance; resistance and resistivity; I-V characteristics; resistors in series and in parallel; e.m.f.; internal resistance; power. In the previous
More informationChapter 3. Chapter 3
Chapter 3 Review of V, I, and R Voltage is the amount of energy per charge available to move electrons from one point to another in a circuit and is measured in volts. Current is the rate of charge flow
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 informationAP Physics Electricity and Magnetism #3 Capacitors, Resistors, Ohm s Law, Electric Power
Name Period AP Physics Electricity and Magnetism #3 Capacitors, Resistors, Ohm s Law, Electric Power Dr. Campbell 1. The two plates of a capacitor hold +2500 µc and -2500 µc of charge, respectively, when
More informationPHYS 1444 Section 003. Lecture #12
Chapter 5 Power PHYS 1444 Section 003 Alternating Current Microscopic Current Chapter 6 EMF and Terminal Voltage Lecture #1 Tuesday October 9, 01 Dr. Andrew Brandt Resistors in Series and Parallel Energy
More informationTest Review Electricity
Name: Date: 1. An operating television set draws 0.71 ampere of current when connected to a 120-volt outlet. Calculate the time it takes the television to consume 3.0 10 5 joules of electric energy. [Show
More informationName: Class: Date: 1. Friction can result in the transfer of protons from one object to another as the objects rub against each other.
Class: Date: Physics Test Review Modified True/False Indicate whether the statement is true or false. If false, change the identified word or phrase to make the statement true. 1. Friction can result in
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 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 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 1-20.
More informationAlgebra Based Physics
Page 1 of 105 Algebra Based Physics Electric Current & DC Circuits 2015-10-06 www.njctl.org Page 2 of 105 Electric Current & DC Circuits Circuits Conductors Resistivity and Resistance Circuit Diagrams
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 informationChapter 18 Electric Currents
Chapter 18 Electric Currents 1 The Electric Battery Volta discovered that electricity could be created if dissimilar metals were connected by a conductive solution called an electrolyte. This is a simple
More informationChapter 28 Solutions
Chapter 8 Solutions 8.1 (a) P ( V) R becomes 0.0 W (11.6 V) R so R 6.73 Ω (b) V IR so 11.6 V I (6.73 Ω) and I 1.7 A ε IR + Ir so 15.0 V 11.6 V + (1.7 A)r r 1.97 Ω Figure for Goal Solution Goal Solution
More informationQuestion 3: How is the electric potential difference between the two points defined? State its S.I. unit.
EXERCISE (8 A) Question : Define the term current and state its S.I unit. Solution : Current is defined as the rate of flow of charge. I = Q/t Its S.I. unit is Ampere. Question 2: Define the term electric
More informationChapter 25 Electric Currents and Resistance. Copyright 2009 Pearson Education, Inc.
Chapter 25 Electric Currents and Resistance Units of Chapter 25 The Electric Battery Electric Current Ohm s Law: Resistance and Resistors Resistivity Electric Power Units of Chapter 25 Power in Household
More informationChapter 3: Electric Current And Direct-Current Circuits
Chapter 3: Electric Current And Direct-Current 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 informationResistance Learning Outcomes
Resistance Learning Outcomes Define resistance and give its unit. Solve problems about resistance. State Ohm s Law. HL: Derive the formulas for resistors in series and parallel. Solve problems about resistors
More informationElectricity and Magnetism Module 4 Student Guide
Electricity and Magnetism Module 4 Student Guide Note: each time you are finished with a circuit we ask that you disconnect all wires, so that the next circuit you investigate starts with a blank slate.
More informationVersion 001 CIRCUITS holland (1290) 1
Version CIRCUITS holland (9) This print-out should have questions Multiple-choice questions may continue on the next column or page find all choices before answering AP M 99 MC points The power dissipated
More informationDesigning Information Devices and Systems I Fall 2018 Lecture Notes Note Resistive Touchscreen - expanding the model
EECS 16A Designing Information Devices and Systems I Fall 2018 Lecture Notes Note 13 13.1 Resistive Touchscreen - expanding the model Recall the physical structure of the simple resistive touchscreen given
More informationResistance Learning Outcomes. Resistance Learning Outcomes. Resistance
Resistance Learning Outcomes Define resistance and give its unit. Solve problems about resistance. State Ohm s Law. HL: Derive the formulas for resistors in series and parallel. Solve problems about resistors
More informationRelating Voltage, Current and Resistance
Relating Voltage, Current and Resistance Using Ohm s Law in a simple circuit. A Simple Circuit Consists of:! A voltage source often a battery! A load such as a bulb! Conductors arranged to complete a circuit
More informationAP Physics C - E & M
Slide 1 / 27 Slide 2 / 27 AP Physics C - E & M Current, Resistance & Electromotive Force 2015-12-05 www.njctl.org Slide 3 / 27 Electric Current Electric Current is defined as the movement of charge from
More informationLab 4. Current, Voltage, and the Circuit Construction Kit
Physics 2020, Spring 2009 Lab 4 Page 1 of 8 Your name: Lab section: M Tu Wed Th F TA name: 8 10 12 2 4 Lab 4. Current, Voltage, and the Circuit Construction Kit The Circuit Construction Kit (CCK) is a
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 informationChapter 25 Electric Currents and. Copyright 2009 Pearson Education, Inc.
Chapter 25 Electric Currents and Resistance 25-1 The Electric Battery Volta discovered that electricity could be created if dissimilar metals were connected by a conductive solution called an electrolyte.
More informationPhysicsAndMathsTutor.com
Electricity May 02 1. The graphs show the variation with potential difference V of the current I for three circuit elements. PhysicsAndMathsTutor.com When the four lamps are connected as shown in diagram
More informationMasteringPhysics: Assignment Print View. Problem 30.50
Page 1 of 15 Assignment Display Mode: View Printable Answers phy260s08 homework 13 Due at 11:00pm on Wednesday, May 14, 2008 View Grading Details Problem 3050 Description: A 15-cm-long nichrome wire is
More informationChapter 26 & 27. Electric Current and Direct- Current Circuits
Chapter 26 & 27 Electric Current and Direct- Current Circuits Electric Current and Direct- Current Circuits Current and Motion of Charges Resistance and Ohm s Law Energy in Electric Circuits Combination
More information2. In words, what is electrical current? 3. Try measuring the current at various points of the circuit using an ammeter.
PS 12b Lab 1a Fun with Circuits Lab 1a Learning Goal: familiarize students with the concepts of current, voltage, and their measurement. Warm Up: A.) Given a light bulb, a battery, and single copper wire,
More informationTARGET STUDY MATERIAL
TARGET STUDY MATERIAL CBSE - X SCIENCE AND MATHS VOL I 1) PHYSICS - 3-75 2) CHEMISTRY - 79-138 3) BIOLOGY - 141-214 4) MATHS - 217-325 TARGET EDUCATIONAL INSTITUTION Target Educational institution is the
More informationChapter 28: Fundamentals of Circuits
Chapter 8: Fundamentals of Circuits Source of Electric Potential the Mechanical Battery (the Van de Graaff VdG) What determines how much potential difference the motor of the VdG can maintain in order
More information( ) ( ) = q o. T 12 = τ ln 2. RC Circuits. 1 e t τ. q t
Objectives: To explore the charging and discharging cycles of RC circuits with differing amounts of resistance and/or capacitance.. Reading: Resnick, Halliday & Walker, 8th Ed. Section. 27-9 Apparatus:
More informationElectric Currents. Resistors (Chapters 27-28)
Electric Currents. Resistors (Chapters 27-28) Electric current I Resistance R and resistors Relation between current and resistance: Ohm s Law Resistivity ρ Energy dissipated by current. Electric power
More informationChapter 26 Examples : DC Circuits Key concepts:
Chapter 26 Examples : DC Circuits Key concepts: Internal resistance : battery consists of some idealized source of voltage (called the electromotive force, or EMF, which uses the symbol ξ) and an effective
More informationAn Introduction to Electricity and Circuits
An Introduction to Electricity and Circuits Materials prepared by Daniel Duke 4 th Sept 2013. This document may be copied and edited freely with attribution. This course has been designed to introduce
More informationChapter 25 Electric Currents and Resistance. Copyright 2009 Pearson Education, Inc.
Chapter 25 Electric Currents and Resistance 25-4 Resistivity Example 25-5: Speaker wires. Suppose you want to connect your stereo to remote speakers. (a) If each wire must be 20 m long, what diameter copper
More informationVoltage Current and Resistance
ELEN 236 oltage, Current and Resistance oltage Current and Resistance Basics (ll bout Circuits: DC-Ch1) (Q s 1-22) Look at EpropsF Water nalogy (remember to press and hold Low, Medium, or High to get pumps
More informationMeasurement of Electrical Resistance and Ohm s Law
Measurement of Electrical Resistance and Ohm s Law Objectives In this experiment, measurements of the voltage across a wire coil and the current in the wire coil will be used to accomplish the following
More informationBYU s EV1 Electric Dragster
BYU s EV1 Electric Dragster Powered by a bank of 160 ultracapacitors. http://newsnet.byu.edu/story.cfm/44205 http://www.youtube.com/watch?v=fi_g2nja3_s BYU s EV1 Electric Dragster A bank of 160 ultra-capacitors
More informationElectron 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 informationChapter 26 Direct-Current Circuits
Chapter 26 Direct-Current Circuits 1 Resistors in Series and Parallel In this chapter we introduce the reduction of resistor networks into an equivalent resistor R eq. We also develop a method for analyzing
More informationChapter 28. Direct Current Circuits
Chapter 28 Direct Current Circuits Circuit Analysis Simple electric circuits may contain batteries, resistors, and capacitors in various combinations. For some circuits, analysis may consist of combining
More information52 VOLTAGE, CURRENT, RESISTANCE, AND POWER
52 VOLTAGE, CURRENT, RESISTANCE, AND POWER 1. What is voltage, and what are its units? 2. What are some other possible terms for voltage? 3. Batteries create a potential difference. The potential/voltage
More informationExam 3--PHYS 102--S14
Name: Exam 3--PHYS 102--S14 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Which of these statements is always true? a. resistors in parallel have the
More informationClicker Session Currents, DC Circuits
Clicker Session Currents, DC Circuits Wires A wire of resistance R is stretched uniformly (keeping its volume constant) until it is twice its original length. What happens to the resistance? 1) it decreases
More informationNotes: Ohm s Law and Electric Power
Name: Date: / / 644 Intro Physics Notes: Ohm s Law and Electric Power Ohm s Law: Important Terms Term Symbol Units Definition 1. current I amps flow of electric charges through a conductor 2. voltage V
More informationSIMPLE D.C. CIRCUITS AND MEASUREMENTS Background
SIMPLE D.C. CICUITS AND MEASUEMENTSBackground This unit will discuss simple D.C. (direct current current in only one direction) circuits: The elements in them, the simple arrangements of these elements,
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 information