Chapter 25 Electric Currents and Resistance. Copyright 2009 Pearson Education, Inc.


 Bertina Rachel Gallagher
 4 years ago
 Views:
Transcription
1 Chapter 25 Electric Currents and Resistance
2 254 Resistivity Example 255: Speaker wires. Suppose you want to connect your stereo to remote speakers. (a) If each wire must be 20 m long, what diameter copper wire should you use to keep the resistance less than 0.10 Ω per wire? (b) If the current to each speaker is 4.0 A, what is the potential difference, or voltage drop, across each wire?
3 254 Resistivity For any given material, the resistivity increases with temperature: T 1 T T 0 0 R T R T T Semiconductors are complex materials, and may have resistivities that decrease with temperature.
4 254 Resistivity Example 257: Resistance thermometer. The variation in electrical resistance with temperature can be used to make precise temperature measurements. Platinum is commonly used since it is relatively free from corrosive effects and has a high melting point. Suppose at 20.0 C the resistance of a platinum resistance thermometer is Ω. When placed in a particular solution, the resistance is Ω. What is the temperature of this solution? Pt m
5 ConcepTest 25.3a Two wires, A and B, are made of the same metal and have equal length, but the resistance of wire A is four times the resistance of wire B. How do their diameters compare? Wires I 1) d A = 4d B 2) d A = 2d B 3) d A = d B 4) d A = 1/2d B 5) d A = 1/4d B
6 ConcepTest 25.3a Two wires, A and B, are made of the same metal and have equal length, but the resistance of wire A is four times the resistance of wire B. How do their diameters compare? Wires I 1) d A = 4d B 2) d A = 2d B 3) d A = d B 4) d A = 1/2d B 5) d A = 1/4d B The resistance of wire A is greater because its area is less than wire B. Since area is related to radius (or diameter) squared, the diameter of A must be two times less than the diameter of B., R ρ A
7 255 Electric Power Power, as in kinematics, is the energy transformed by a device per unit time: or
8 255 Electric Power The unit of power is the watt, W. For ohmic devices, we can make the substitutions:
9 255 Electric Power Example 258: Headlights. Calculate the resistance of a 40W automobile headlight designed for 12 V.
10 255 Electric Power What you pay for on your electric bill is not power, but energy the power consumption multiplied by the time. We have been measuring energy in joules, but the electric company measures it in kilowatthours, kwh: 1 kwh = (1000 W)(3600 s) = 3.60 x 10 6 J.
11 255 Electric Power Example 259: Electric heater. An electric heater draws a steady 15.0 A on a 120V line. How much power does it require and how much does it cost per month (30 days) if it operates 3.0 h per day and the electric company charges 9.2 cents per kwh?
12 257 Alternating Current Current from a battery flows steadily in one direction (direct current, DC). Current from a power plant varies sinusoidally (alternating current, AC).
13 257 Alternating Current The voltage varies sinusoidally with time:, as does the current:
14 257 Alternating Current Multiplying the current and the voltage gives the power:
15 257 Alternating Current Usually we are interested in the average power:.
16 257 Alternating Current The current and voltage both have average values of zero, so we square them, take the average, then take the square root, yielding the rootmeansquare (rms) value:
17 257 Alternating Current Example 2513: Hair dryer. (a) Calculate the resistance and the peak current in a 1000W hair dryer connected to a 120V line. (b) What happens if it is connected to a 240V line in Britain?
18 258 Microscopic View of Electric Current: Current Density and Drift Velocity Electrons in a conductor have large, random speeds just due to their temperature. When a potential difference is applied, the electrons also acquire an average drift velocity, which is generally considerably smaller than the thermal velocity.
19 258 Microscopic View of Electric Current: Current Density and Drift Velocity We define the current density (current per unit area) this is a convenient concept for relating the microscopic motions of electrons to the macroscopic current: If the current is not uniform:. (Remember the water in the pipe)
20 258 Microscopic View of Electric Current: Current Density and Drift Velocity This drift speed is related to the current in the wire, and also to the number of electrons per unit volume: and
21 258 Microscopic View of Electric Current: Current Density and Drift Velocity Example 2514: Electron speeds in a wire. A copper wire 3.2 mm in diameter carries a 5.0 A current. Determine (a) the current density in the wire, and (b) the drift velocity of the free electrons. (c) Estimate the rms speed of electrons assuming they behave like an ideal gas at 20 C. Assume that one electron per Cu atom is free to move (the others remain bound to the atom).
22 258 Microscopic View of Electric Current: Current Density and Drift Velocity The electric field inside a currentcarrying wire can be found from the relationship between the current, voltage, and resistance. Writing R = ρ l/a, I = ja, and V = El, and substituting in Ohm s law gives:
23 258 Microscopic View of Electric Current: Current Density and Drift Velocity Example 2515: Electric field inside a wire. What is the electric field inside the wire of the earlier example? (The current density was found to be 6.2 x 10 5 A/m 2.)
24 259 Superconductivity In general, resistivity decreases as temperature decreases. Some materials, however, have resistivity that falls abruptly to zero at a very low temperature, called the critical temperature, T C. Purely quantum mechanical; CANNOT be explained using classical physics.
25 259 Superconductivity Experiments have shown that currents, once started, can flow through these materials for years without decreasing even without a potential difference. Critical temperatures are low; for many years no material was found to be superconducting above 23 K. Since 1987, new materials have been found that are superconducting below 90 K, and work on higher temperature superconductors is continuing.
26 Summary of Chapter 25 A battery is a source of constant potential difference. Electric current is the rate of flow of electric charge. Conventional current is in the direction that positive charge would flow. Resistance is the ratio of voltage to current:
27 Summary of Chapter 25 Ohmic materials have constant resistance, independent of voltage. Resistance is determined by shape and material: ρ is the resistivity.
28 Summary of Chapter 25 Power in an electric circuit: Direct current is constant. Alternating current varies sinusoidally:
29 Summary of Chapter 25 The average (rms) current and voltage: Relation between drift speed and current:
30 Chapter 26 DC Circuits
31 261 EMF and Terminal Voltage Electric circuit needs battery or generator to produce current these are called sources of emf. Battery is a nearly constant voltage source, but does have a small internal resistance, which reduces the actual voltage from the ideal emf:
32 261 EMF and Terminal Voltage This resistance behaves as though it were in series with the emf.
33 261 EMF and Terminal Voltage Example 261: Battery with internal resistance. A 65.0Ω resistor is connected to the terminals of a battery whose emf is 12.0 V and whose internal resistance is 0.5 Ω. Calculate (a) the current in the circuit, (b) the terminal voltage of the battery, V ab, and (c) the power dissipated in the resistor R and in the battery s internal resistance r.
34 262 Resistors in Series and in Parallel A series connection has a single path from the battery, through each circuit element in turn, then back to the battery.
35 262 Resistors in Series The current through each resistor is the same; the voltage depends on the resistance. The sum of the voltage drops across the resistors equals the battery voltage: V V V V IR IR IR I R1 R2 R3 IReq Series
36 262 Resistors in Series From this we get the equivalent resistance (that single resistance that gives the same current in the circuit): Unless an internal resistance r is specified assume V constant.
37 ConcepTest 26.1a Series Resistors I Assume that the voltage of the battery is 9 V and that the three resistors are identical. What is the potential difference across each resistor? 1) 12 V 2) zero 3) 3 V 4) 4 V 5) you need to know the actual value of R 9 V
38 ConcepTest 26.1a Series Resistors I Assume that the voltage of the battery is 9 V and that the three resistors are identical. What is the potential difference across each resistor? Since the resistors are all equal, the voltage will drop evenly across the 3 resistors, with 1/3 of 9 V across each one. So we get a 3 V drop across each. 1) 12 V 2) zero 3) 3 V 4) 4 V 5) you need to know the actual value of R 9 V Followup: What would be the potential difference if R = 1, 2, 3?
39 ConcepTest 26.1b Series Resistors II 1) 12 V In the circuit below, what is the voltage across R 1? 2) zero 3) 6 V 4) 8 V 5) 4 V R 1 = 4 R 2 = 2 12 V
40 ConcepTest 26.1b Series Resistors II 1) 12 V In the circuit below, what is the voltage across R 1? 2) zero 3) 6 V 4) 8 V 5) 4 V The voltage drop across R 1 has to be twice as big as the drop across R 2. This means that V 1 = 8 V and V 2 = 4 V. Or else you could find the current I = V/R = (12 V)/(6 = 2 A, and then use R 1 = 4 R 2 = 2 12 V Ohm s law to get voltages. Followup: What happens if the voltage is doubled?
41 262 Resistors in Parallel A parallel connection splits the current; the voltage across each resistor is the same:
42 262 Resistors in Parallel The total current is the sum of the currents across each resistor:,
43 262 Resistors in Parallel This gives the reciprocal of the equivalent resistance:
44 262 Resistors in Parallel An analogy using water may be helpful in visualizing parallel circuits. The water (current) splits into two streams; each falls the same height, and the total current is the sum of the two currents. With two pipes open, the resistance to water flow is half what it is with one pipe open.
45 262 Resistors in Series and in Parallel Conceptual Example 262: Series or parallel? (a) The lightbulbs in the figure are identical. Which configuration produces more light? (b) Which way do you think the headlights of a car are wired? Ignore change of filament resistance R with current.
46 ConcepTest 26.2a Parallel Resistors I 1) 10 A In the circuit below, what is the current through R 1? 2) zero 3) 5 A 4) 2 A 5) 7 A R 2 = 2 R 1 = 5 10 V
47 ConcepTest 26.2a Parallel Resistors I 1) 10 A In the circuit below, what is the current through R 1? 2) zero 3) 5 A 4) 2 A 5) 7 A The voltage is the same (10 V) across each resistor because they are in parallel. Thus, we can use Ohm s law, V 1 = I 1 R 1 to find the current I 1 = 2 A. R 2 = 2 R 1 = 5 Followup: What is the total current through the battery? 10 V
48 ConcepTest 26.2b Points P and Q are connected to a battery of fixed voltage. As more resistors R are added to the parallel circuit, what happens to the total current in the circuit? Parallel Resistors II 1) increases 2) remains the same 3) decreases 4) drops to zero
49 ConcepTest 26.2b Points P and Q are connected to a battery of fixed voltage. As more resistors R are added to the parallel circuit, what happens to the total current in the circuit? Parallel Resistors II 1) increases 2) remains the same 3) decreases 4) drops to zero As we add parallel resistors, the overall resistance of the circuit drops. Since V = IR, and V is held constant by the battery, when resistance decreases, the current must increase. Followup: What happens to the current through each resistor?
50 262 Resistors in Series and in Parallel Conceptual Example 263: An illuminating surprise. A 100W, 120V lightbulb and a 60W, 120V lightbulb are connected in two different ways as shown. In each case, which bulb glows more brightly? Ignore change of filament resistance with current (and temperature).
51 262 Resistors in Series and in Parallel Example: Current in one branch. What is the current through the 500Ω resistor shown?
52 262 Resistors in Series and in Example 268: Analyzing a circuit. A 9.0V battery whose internal resistance r is 0.50 Ω is connected in the circuit shown. (a) How much current is drawn from the battery? (b) What is the terminal voltage of the battery? Parallel Note: slight error in figure and text
Chapter 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 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 informationLecture (07) Electric Current and Resistance By: Dr. Ahmed ElShafee Dr. Ahmed ElShafee, ACU : Spring 2015, Physics II
Lecture (07) Electric Current and Resistance By: Dr. Ahmed ElShafee ١ The glow of the thin wire filament of a light bulb is caused by the electric current passing through it. Electric energy is transformed
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 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 informationLecture PowerPoints. Chapter 18 Physics: Principles with Applications, 6 th edition Giancoli
Lecture PowerPoints Chapter 18 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for
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 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 informationChapter 19. Electric Current, Resistance, and DC Circuit Analysis
Chapter 19 Electric Current, Resistance, and DC Circuit Analysis I = dq/dt Current is charge per time SI Units: Coulombs/Second = Amps Direction of Electron Flow _ + Direction of Conventional Current:
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 informationPHYS 1444 Section 002 Lecture #13
PHYS 1444 Section 002 Lecture #13 Monday, Oct. 16, 2017 Dr. Animesh Chatterjee (disguising as Dr. Yu) Chapter 25 Electric Current Ohm s Law: Resisters, Resistivity Electric Power Alternating Current Microscopic
More informationElectric Currents & Resistance
Electric Currents & Resistance Electric Battery A battery produces electricity by transforming chemical energy into electrical energy. The simplest battery contains two plates or rods made of dissimilar
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 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 informationA free web support in Education. Internal resistance of the battery, r = 3 Ω. Maximum current drawn from the battery = I According to Ohm s law,
Exercises Question 3.1: The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is 0.4Ω, what is the maximum current that can be drawn from the battery? Answer 3.1: Emf
More informationInformation for Makeup exam is posted on the course website.
Information for Makeup exam is posted on the course website. Three resistors are connected to a 6V battery as shown. The internal resistance of the battery is negligible. What is the current through the
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 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 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 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 informationConcepTest Clicker Questions. Chapter 26 Physics: for Scientists & Engineers with Modern Physics, 4th edition Giancoli
ConcepTest Clicker Questions Chapter 26 Physics: for Scientists & Engineers with Modern Physics, 4th edition Giancoli 2008 Pearson Education, Inc. This work is protected by United States copyright laws
More informationPHYS 1442 Section 001. Lecture #5. Chapter 18. Wednesday, June 17, 2009 Dr. Jaehoon Yu
PHYS 1442 Section 001 Chapter 18 Lecture #5 Dr. The Electric Battery Ohm s Law: Resisters Resistivity Electric Power Alternating Current Power Delivered by AC Today s homework is #3, due 9pm, Thursday,
More informationELECTRICITY UNIT REVIEW
ELECTRICITY UNIT REVIEW S1304: How does the Atomic Model help to explain static electricity? 1. Which best describes static electricity? a) charges that can be collected and held in one place b) charges
More informationPhysics for Scientists & Engineers 2
Review The resistance R of a device is given by Physics for Scientists & Engineers 2 Spring Semester 2005 Lecture 8 R =! L A ρ is resistivity of the material from which the device is constructed L is the
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 informationPHYS 1441 Section 001 Lecture #10 Tuesday, June 21, 2016
PHYS 1441 Section 001 Lecture #10 Tuesday, June 21, 2016 Chapter 25 Electric Current and Resistance The Battery Ohm s Law: Resisters, Resistivity Electric Power Alternating Current Microscopic View of
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 informationElectrodynamics. Review 8
Unit 8 eview: Electrodynamics eview 8 Electrodynamics 1. A 9.0 V battery is connected to a lightbulb which has a current of 0.5 A flowing through it. a. How much power is delivered to the b. How much energy
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 informationConcepTest PowerPoints
ConcepTest PowerPoints Chapter 19 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for
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 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 informationWhat is an Electric Current?
Electric Circuits NTODUCTON: Electrical circuits are part of everyday human life. e.g. Electric toasters, electric kettle, electric stoves All electrical devices need electric current to operate. n this
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 informationphysics for you February 11 Page 68
urrent Electricity Passage 1 4. f the resistance of a 1 m length of a given wire t is observed that good conductors of heat are also is 8.13 10 3 W, and it carried a current 1, the good conductors of electricity.
More informationCircuits. PHY2054: Chapter 18 1
Circuits PHY2054: Chapter 18 1 What You Already Know Microscopic nature of current Drift speed and current Ohm s law Resistivity Calculating resistance from resistivity Power in electric circuits PHY2054:
More informationChapter 24: Electric Current
Chapter 24: Electric Current Electric current Electric current is a net flow of electric charge. Quantitatively, current is the rate at which charge crosses a given area. I = dq dt dq = q(n AL)=q(n Av
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 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 informationCircuitsOhm's Law. 1. Which graph best represents the relationship between the electrical power and the current in a resistor that obeys Ohm s Law?
1. Which graph best represents the relationship between the electrical power and the current in a resistor that obeys Ohm s Law? 2. A potential drop of 50 volts is measured across a 250 ohm resistor.
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 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 informationPHYS 1444 Section 004 Lecture #10
PHYS 1444 Section 004 Lecture #10 Dr. Electric Current and Resistance The Battery Ohm s Law: Resisters Resistivity Electric Power Alternating Current Power Delivered by AC Today s homework is #6, due 10pm,
More informationChapter 24: Electric Current
Chapter 24: Electric Current Current Definition of current A current is any motion of charge from one region to another. Suppose a group of charges move perpendicular to surface of area A. The current
More informationCurrent Electricity.notebook. December 17, 2012
1 Circuit Diagrams and Assembly 1. Draw a circuit diagram containing a battery, a single throw switch, and a light. 2. Once the diagram has been checked by your teacher, assemble the circuit. Keep the
More information12/2/2018. Monday 12/17. Electric Charge and Electric Field
Electricity Test Monday 1/17 Electric Charge and Electric Field 1 In nature, atoms are normally found with equal numbers of protons and electrons, so they are electrically neutral. By adding or removing
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 informationChapter 18. Direct Current Circuits
Chapter 18 Direct Current Circuits Sources of emf The source that maintains the current in a closed circuit is called a source of emf Any devices that increase the potential energy of charges circulating
More informationCh. 21: Current, Resistance, Circuits
Ch. 21: Current, Resistance, Circuits Current: How charges flow through circuits Resistors: convert electrical energy into thermal/radiative energy Electrical Energy & Power; Household Circuits TimeDependent
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 informationChapter 27: Current & Resistance. HW For Chapter 27: 6, 18, 20, 30, 42, 48, 52, 56, 58, 62, 68
Chapter 27: Current & Resistance HW For Chapter 27: 6, 18, 20, 30, 42, 48, 52, 56, 58, 62, 68 Positive Charges move from HI to LOW potential. HI V LOW V Negative Charges move from LOW to HI potential.
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 informationChapter 21 Electric Current and Direct Current Circuits
Chapter 21 Electric Current and Direct Current Circuits 1 Overview of Chapter 21 Electric Current and Resistance Energy and Power in Electric Circuits Resistors in Series and Parallel Kirchhoff s Rules
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 informationCHAPTER 20 ELECTRIC CIRCUITS
CHAPTER 20 ELECTRIC CIRCUITS PROBLEMS. SSM REASONING Since current is defined as charge per unit time, the current used by the portable compact disc player is equal to the charge provided by the battery
More informationElectric Charge and Electric field
Electric Charge and Electric field ConcepTest 16.1a Electric Charge I Two charged balls are repelling each other as they hang from the ceiling. What can you say about their charges? 1) one is positive,
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 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 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 informationPhysics 7B1 (A/B) Professor Cebra. Winter 2010 Lecture 2. Simple Circuits. Slide 1 of 20
Physics 7B1 (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 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 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 informationDC Circuits. Circuits and Capacitance Worksheet. 10 Ω resistance. second? on the sodium is the same as on an electron, but positive.
Circuits and Capacitance Worksheet DC Circuits 1. A current of 1.30 A flows in a wire. How many electrons are flowing past any point in the wire per second? 2. What is the current in amperes if 1200 Na
More informationGeneral Physics (PHY 2140)
General Physics (PHY 2140) Lecture 9 Electrodynamics Electric current temperature variation of resistance electrical energy and power http://www.physics.wayne.edu/~apetrov/phy2140/ Chapter 1718 1 Department
More informationDownloaded from
CHAPTER 12 ELECTRICITY Electricity is a general term that encompasses a variety of phenomena resulting from the presence and flow of electric charge. These include many easily recognizable phenomena such
More informationLorik educational academyvidyanagar
Lorik educational academyvidyanagar 9849180367  Section: Senior TOPIC: CURRENT ELECTRICITY
More informationPHYS 1444 Section 02 Review #2
PHYS 1444 Section 02 Review #2 November 9, 2011 Ian Howley 1 1444 Test 2 Eq. Sheet Terminal voltage Resistors in series Resistors in parallel Magnetic field from long straight wire Ampére s Law Force on
More informationRMS values. Book page
RMS values Book page 443444 cgrahamphysics.com 015 Review When angle between normal to loop and field lines is θ = 90 0 max flux, Φ = NAB cos θ min emf, emf = ωnab sin ωt θ = 0 0 min flux, max emf cgrahamphysics.com
More information11. ELECTRIC CURRENT. Questions and Answers between the forces F e and F c. 3. Write the difference between potential difference and emf. A.
CLSS10 1. Explain how electron flow causes electric current with LorentzDrude theory of electrons?. Drude and Lorentz, proposed that conductors like metals contain a large number of free electrons while
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 informationChapter 20: Electric Current, Resistance & Ohm s Law. Brent Royuk Phys112 Concordia University
Chapter 20: Electric Current, Resistance & Ohm s Law Brent Royuk Phys112 Concordia University The Minds of Our Own Challenge Light a bulb with a battery and a wire. Could you do it? 2 Introduction Batteries
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 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 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 informationClass 8. Resistivity and Resistance Circuits. Physics 106. Winter Press CTRLL to view as a slide show. Class 8. Physics 106.
and Circuits and Winter 2018 Press CTRLL to view as a slide show. Last time we learned about Capacitance Problems ParallelPlate Capacitors Capacitors in Circuits Current Ohm s Law and Today we will learn
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 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 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 informationChapter 20: Electric Current, Resistance & Ohm s Law
Chapter 0: Electric Current, Resistance & Brent Royuk Phys11 Concordia University The Minds of Our Own Challenge Light a bulb with a battery and a wire. Could you do it? Introduction Batteries supply
More informationNama :.. Kelas/No Absen :
Nama :.. Kelas/No Absen : TASK 2 : CURRENT AND RESISTANCE 1. A car battery is rated at 80 A h. An amperehour is a unit of: A. power B. energy C. current D. charge E. force 2. Current has units: A. kilowatthour
More informationCurrent and Resistance
Chapter 26 Current and Resistance Copyright 261 Electric Current As Fig. (a) reminds us, any isolated conducting loop regardless of whether it has an excess charge is all at the same potential. No electric
More informationCurrent and Resistance
Chapter 17 Current and esistance Quick Quizzes 1. (d. Negative charges moving in one direction are equivalent to positive charges moving in the opposite direction. Thus, Ia, Ib, Ic, and Id are equivalent
More informationChapter 4. Chapter 4
Chapter 4 Energy 1 n Energy, W, is the ability to do work and is measured in joules. One joule is the work done when a force of one newton is applied through a distance of one meter. The symbol for energy,
More informationDirect Currents. We will now start to consider charges that are moving through a circuit, currents. Sunday, February 16, 2014
Direct Currents We will now start to consider charges that are moving through a circuit, currents. 1 Direct Current Current usually consists of mobile electrons traveling in conducting materials Direct
More informationand in a simple circuit Part 2
Current, Resistance, and Voltage in a simple circuit Part 2 Electric Current Whenever electric charges of like signs move, an electric current is said to exist. Look at the charges flowing perpendicularly
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 00.006 Copper.6 x 00.006 Aluminum.65 x 00.0049 Tungsten
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 informationElectric Current. You must know the definition of current, and be able to use it in solving problems.
Today s agenda: Electric Current. You must know the definition of current, and be able to use it in solving problems. Current Density. You must understand the difference between current and current density,
More informationweek 6 chapter 31 Current and Resistance
week 6 chapter 31 Current and Resistance Which is the correct way to light the lightbulb with the battery? 4) all are correct 5) none are correct 1) 2) 3) Which is the correct way to light the lightbulb
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 informationLecture Outline Chapter 21. Physics, 4 th Edition James S. Walker. Copyright 2010 Pearson Education, Inc.
Lecture Outline Chapter 21 Physics, 4 th Edition James S. Walker Chapter 21 Electric Current and Direct Current Circuits Units of Chapter 21 Electric Current Resistance and Ohm s Law Energy and Power
More informationConcepTest PowerPoints
ConcepTest PowerPoints Chapter 16 Physics: Principles with Applications, 7 th edition Giancoli 2014 Pearson Education, Inc. This work is protected by United States copyright laws and is provided solely
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 informationCollege Physics B  PHY2054C
Power College  PHY2054C and 09/15/2014 My Office Hours: Tuesday 10:00 AM  Noon 206 Keen Building PHY2054C Power First MiniExam this week on Wednesday!! Location: UPL 101, 10:1011:00 AM Exam on chapters
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 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 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 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 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 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 information