Chapter 3: Electric Current and DirectCurrent Circuit


 Blanche Robertson
 3 years ago
 Views:
Transcription
1 Chapter 3: Electric Current and DirectCurrent Circuit n this chapter, we are going to discuss both the microscopic aspect and macroscopic aspect of electric current. Directcurrent is current that flows in one direction.
2 Overview Electric Current Conduction of Electricity dq dt Ohm s Law Electrical Energy W t Drift elocity esistivity Electrical Power v d nae A l P Dependence of esistance on Temperature T T 0 0
3 Overview DirectCurrent Circuit Electromotive Force, nternal esistor & Potential Difference terminal r First Law Kirchhoff s Laws Second Law Potential Divider 2 in out Potentiometer 2 l l 2 esistors Wheatstone Bridge n Series n Parallel X 2 3
4 3. Electric Conduction Describe microscopic model of current Define and use electric current, dq dt Learning Objectives
5 Mechanism of Electric Conduction in Metals v d 0 Before applying electric field Electron move freely and random. Frequently interact with each other. Drift velocity is zero because the free electrons are in constant random motion.
6 Mechanism of Electric Conduction in Metals After applying electric field E v d v d nae F e The freely moving electron experience an electric force and tend to drift towards a direction opposite to the direction of electric field (positive terminal of the battery). The electric current is flowing in the opposite direction of the electron flows. Drift velocity is the mean velocity of the electrons parallel to the direction of the electric field when a potential difference is applied.
7 Electric Current Electric current, is defined as the total charge, Q flowing through an area per unit time, t. (O the rate of charge flow through a conductor) Mathematically, Q t O dq dt t is a scalar quantity. The S.. unit for electric current is ampere (A).
8 Example A current of 2.0 A flows through a copper wire. Calculate a. the amount of charge, and b. the number of electrons flow through a crosssectional area of the copper wire in 30 s. (Given the charge of electron, e =.60x09 C)
9 Example Solution
10 Example Solution
11 3.2 Ohm s Law and esistivity State and use Ohm s Law Define and use resistivity, A l Learning Objectives
12 Ohm s Law Ohm s law states that the potential difference across a conductor, is directly proportional to the current, through it, if its physical conditions and the temperature are constant. where T is constant Mathematically, constant Ohm s Law equation
13 Ohm s Law Graphically, Must start from zero Not all materials obey Ohm s law. Materials that obey Ohm s law are materials that have constant resistance over a wide range of voltage. These materials are called ohmic conductor. Examples: pure metals
14 esistivity esistivity is defined as the resistance of a unit crosssectional area per unit length of the material. t is a measure of a material s ability to oppose the flow of an electric current. A l where l : length A : crosssectional area t is a scalar quantity Unit is ohm meter ( m) esistivity depends on the material. Same materials have same resistivity. t only changes when the temperature of wire/ material changes.
15 Example 2 A wire 4.00 m long and 6.00 mm in diameter has a resistance of 5 m. A potential difference of 23.0 is applied between both end. Determine a. the current in the wire. b. the resistivity of the wire material.
16 Example 2 Solution
17 Example 2 Solution
18 Example 3 Two wires P and Q with circular cross section are made of the same metal and have equal length. f the resistance of wire P is three times greater than that of wire Q, determine the ratio of their diameters.
19 Example 3 Solution
20 3.3 ariation of esistance with Temperature Explain the effect of temperature on electrical resistance in metals. Use resistance, T T 0 0 Learning Objectives
21 Electric esistance of A Metal The resistance of a metal (conductor) depends on a. the nature of the material, (, resistivity) b. the size of the conductor, (l, the length and A, crosssectional area) l A c. the temperature of the conductor. The resistance of metals increases with increasing temperature. (T, )
22 The Effect of Temperature on Electrical esistance in Metals Explanation:. As temperature increases, the ions of the conductor vibrate with greater amplitude. 2. More collisions occur between free electrons and ions. 3. These electrons are slowed down thus increases the resistance.
23 ariation of esistance with Temperature The fractional change in resistance per unit rise in temperature is known as temperature coefficient of resistance, α: α is a constant value and it is depends on the material. T 0 T T T T T T
24 ariation of esistance with Temperature The resistance of a metal can be represented by the equation below: T T 0 0 where = the resistance at temperature T, o = the resistance at temperature T 0 = 20 o C or 0 o C, T = final temperature T o = reference temperature (20 o C or 0 o C) = the temperature coefficient of resistance ( o C  )
25 Example 4 A platinum wire has a resistance of 0.5 Ω at 0 C. t is placed in a water bath where its resistance rises to a final value of 0.6 Ω. What is the temperature of the bath? (Given the temperature coefficient of resistance of platinum is C  )
26 Example 4 Solution
27 Example 5 A copper wire has a resistance of 25 mω at 20 C. When the wire is carrying a current, heat produced by the current causes the temperature of the wire to increase by 27 C. a. Calculate the change in the wire s resistance. b. f its original current was 0.0 ma and the potential difference across wire remains constant, determine the final current of the copper wire. (Given the temperature coefficient of resistance of copper is C  )
28 Example 5 Solution
29 Example 5 Solution
30 3.4 Electromotive Force (emf), nternal esistance and Potential Difference Define emf, ε of a battery Explain the relationship between emf of a battery and potential difference across the battery terminals Use terminal voltage r Learning Objectives
31 What is inside a battery
32 How do batteries work?
33 Electromotive Force, ε ε Electromotive force (e.m.f.), is defined as the energy provided by the source (battery/ cell) to each unit charge that flows from the source. t is the maximum potential difference across its terminals when it is not connected to a circuits. Unit is volt ().
34 Terminal Potential Difference, Terminal potential difference (voltage), is defined as the work done in bringing a unit (test) charge from the negative to the positive terminals of the battery through the external resistance only. t is the potential difference across the terminals of a battery when there is a current flowing through it. Unit is volt ().
35 nternal esistance, r n a cell or battery, the negative ions are attracted by anode and the positive ions are attracted by the cathode. The flow of these ions produces current. However the collisions between the ions and the recombination of opposite ions reduce the flow of current. This resistance in the cell is called internal resistance, r.
36 elationship between ε, and r terminal lost r r Total resistance in the circuit
37 Note terminal < ε when the battery of emf ε is connected to the external circuit with resistance. terminal > ε when the battery of emf ε is being charged by other battery. terminal = ε when the battery of emf ε has no internal resistance (r = 0) and connected to the external circuit with resistance.
38 Example 6 A battery of internal resistance 0.3 is connected across a 5.0 resistor. The terminal potential difference measured by the voltmeter is 2.5. Calculate the e.m.f. of the battery.
39 Example 6 Solution
40 Example 7 When a 0 resistor is connected across the terminals of a cell of e.m.f. and internal resistance r, a current of 0.0 A flows through the resistor. f the 0 resistor is replaced with a 3.0 resistor, the current increases to 0.24 A. Find and r.
41 Example 7 Solution
42 Example 7 Solution
43 Example 8 A battery has an e.m.f. of 9.0 and an internal resistance of 6.0. Determine a. the potential difference across its terminals when it is supplying a current of 0.50 A, b. the maximum current which the battery could supply.
44 Example 8 Solution
45 Example 8 Solution
46 3.5 Electrical Energy and Power Use power, P = electrical energy, W = t Learning Objectives
47 Electrical Energy, W Electrical (potential) energy, W is the energy gained by the charge Q from a voltage source (battery) having a terminal voltage. The faster the electric charges are moving the more electrical energy they carry. The work done by the source on the charge is given by: Given Q = t, W Q W t For source
48 Electrical Energy, W Since =, electrical energy can also be written as: W 2 t O W 2 t The unit for electrical energy is Joule (J).
49 Electrical Power, P Electric power is defined as the rate of energy delivered to the external circuit by the battery. P W t t t P For source Since =, electrical power can also be written as: P 2 O P 2 The unit for electrical power is Watt (W).
50 Example 9 a. Calculate the resistance of a 40 W automobile headlight designed for 2? b. The current through a refrigerator of resistance 2 Ω is 3 A. What is the power consumed by the refrigerator?
51 Example 9 Solution
52 Example 0 n figure above, a battery with an e.m.f. of 2 and an internal resistance of.0 is connected to a 5Ω resistor. Determine a. the rate of energy transferred to electrical energy in the battery, b. the rate of heat dissipated in the battery, c. the amount of heat loss in the 5.0 resistor if the current flows through it for 20 minutes.
53 Example 0 Solution
54 Example 0 Solution
55 evision a. A dry cell of e.m.f..50 is connected in series with a resistor and another battery. When a current of 3.0 A flows from the cell, the voltage across the cell is What is the internal resistance of the dry cell? (0.36 Ω) b. The e.m.f. of a cell is.5 and its internal resistance is 0.5 Ω. Determine the power supplied to an external resistor of resistance 2.5 Ω. (0.625 W)
56 3.6 esistors in Series and Parallel Derive and determine effective resistance of resistors in series and parallel Learning Objectives
57 esistor in Series The symbol of resistor in electrical circuit can be shown in esistors in Series O
58 esistor in Series The same current flows through each resistor where 2 3 Assuming that the connecting wires have no resistance, the total potential difference, is given by 2 3 From the definition of resistance, ; 2 2 ; 3 3 ; eq Therefore, eq 2 3 eq 2 3
59 esistor in Parallel esistors in Parallel
60 esistor in Parallel There is the same potential difference, across each resistor where 2 3 Charge is conserved, therefore the total current in the circuit is given by 2 3 From the definition of resistance, ; 2 ; 3 ; 2 3 Therefore, eq 2 3 eq eq 2 3
61 Example For the circuit shown below, Calculate : a. the total resistance of the circuit. b. the total current in the circuit. c. the potential difference across 4.0 resistor.
62 Example Solution
63 Example Solution
64 Example 2 For the circuit shown below, calculate the equivalent resistance between points x and y.
65 Example 2 Solution
66 A B 5 Since 4 and 5 are in series: X 4 5 X is constant from point A to point B. A 3 Step X X 3 3 B
67 A X B X Since X and 2 have same potential difference (point A and B), they are in parallel: Y Y Y X X Step 2 Y Y Y 3 3
68 A Y Y 3 Y Since Y and 3 are in series: Z Z Y 3 Y is constant from point A to point C. Y 3 C 3 A Step 3 Z Z Y C
69 A C Z Z Y Since Z and have same potential difference (point A and C), they are in parallel: eq eq eq Z Y Z Step 4 eq eq eq Answer: eq 0.79
70 3.7 Kirchhoff s Laws State and use Kirchhoff s Laws (Maximum two closed circuit loops) Learning Objectives
71 Kirchhoff s First Laws Also known as Kirchhoff s Junction/Current Law States the algebraic sum of the currents entering any junctions in a circuit must equal the algebraic sum of the currents leaving that junction. Obeys the principle of conservation of charge. Mathematically, For example: in out
72 Kirchhoff s Second Laws Also known as Kirchhoff s Loop/oltage Law States in any closed loop, the algebraic sum of e.m.f.s is equal to the algebraic sum of the products of current and resistance or in any closed loop. Obeys the principle of conservation of energy. Mathematically,
73 Kirchhoff s Second Laws Sign convention for e.m.f., ε: Sign convention for the product of :
74 Problem Solving Strategy For ONE closed circuit. Label the diagram 2. Apply Kirchhoff s Second Law equation 3. Solve the equations Only one loop, no junction in the circuit: Don t have to apply Kirchhoff s first law ɛ ɛ 2 2 Kirchhoff s second law:
75 Problem Solving Strategy For TWO closed circuits. Label the diagram 2. Apply Kirchhoff s First Law equation 3. Apply Kirchhoff s Second Law 2 equations 4. Use scientific calculator to solve the simultaneous equations ε Kirchhoff s first law: in out ε Kirchhoff s second law: Loop : 2 22 Loop 2: ( ) 3
76 Example 3 Using Kirchhoff s rules, find the current in each resistor.
77 Example 3 Solution
78 Example 4 Calculate, ε X and
79 Example 4 Solution Step : Label the diagram ε X = Ω 0.84 A ε Y Ω A Step 2: Apply Kirchhoff s First Law in 2 out A
80 Example 4 Solution Step 3: Apply Kirchhoff s Second Law ε X = 7.2 ε Y 4.0 Ω Ω 0.84 A Loop : X Y A 2 Loop 2: Y 2 2 2
81 Example 4 Solution Step 4: Solving the simultaneous equations Loop : Y X Y Y 9.84 Loop 2: Y 9.84 Y Y (.68.0) (0.32 ) 33.0
82 Example 5 Using Kirchhoff s rules, find the current in each resistor. Answer: =3.75 A, 2 = 5.0 A, 3 =.25 A
83 Example 6 For the circuit shown below, Given = 8, 2 = 2, 3 = 3, = and = 3 A. gnore the internal resistance in each battery. Calculate a. the currents and 2. b. the e.m.f. 2. Answer: A, 4 A, 7
84 Example 7 For the circuit shown below, Determine a. the currents, 2 and 3, b. the potential difference across the 6.7 resistor, c. the power dissipated from the.2 resistor. Answer: =0.72 A, 2 =.03 A, 3 =.75 A ; 6.90 ; 3.68 W
85 3.8 Potential Divider Explain principle of potential divider Use equation of potential divider, 2 Learning Objectives
86 Potential Divider Also known as voltage divider. A potential divider produces an output voltage that is a fraction of the supply voltage. This is done by connecting two resistors in series as shown in figure below. 2 Since the current flowing through each resistor is the same, thus eq and eq 2 2 2
87 Potential Divider Therefore, the potential difference (voltage) across is given by 2 Similarly,
88 Potential Divider esistance and 2 can be replaced by a uniform homogeneous wire as shown in figure below. a l c l 2 2 b Since ρl A Therefore, the potential difference (voltage) across the wire with length l l l 2 and l2 2 l l 2
89 Summary 2 2 a l c l 2 2 b l eff 2 2 l total l l 2 2
90 Example 8 esistors of 3.0 Ω and 6.0 Ω are connected in series to a 2.0 battery of negligible internal resistance. Determine the potential difference across the a. 3.0 Ω resistor b. 6.0 Ω resistors
91 Example 8 Solution
92 3.9 Potentiometer and Wheatstone Bridge Explain principles of potentiometer and Wheatstone Bridge and their applications. Use related equations for potentiometer, and for Wheatstone Bridge, 2 l l 2 2 X Learning Objectives
93 Potentiometer 0 0 G No current flow 8 0
94 Potentiometer The working of potentiometer is based upon the fact that fall of the potential across any portion of the wire is directly proportional to the length of the wire provided wire has uniform cross section area and constant current flowing through it. A +  x G C (Unknown oltage) l because l B Jockey The potentiometer is balanced when the jockey (sliding contact) is at such a position on wire AB that there is no current through the galvanometer. Galvanometer reading = 0
95 Application : To measure the unknown e.m.f. C A B +  x (Unknown oltage) G Jockey The potentiometer is balanced when the reading of galvanometer is equal to zero (no current through the galvanometer). X AC
96 Application : To measure the unknown e.m.f. A l Total G C B a l c l 2 2 b AC BC Same as potential divider l Total l AC AC l BC BC
97 Application 2: To compare two e.m.f. l l l A earranging: l () A
98 Application 2: To compare two e.m.f. 2 l2 l2 l A 2 earranging: 2 l (2) A 2
99 Application 2: To compare two e.m.f. () (2) = A l A l l l or 2 2 l
100 Application 3: To measure the internal resistance of a cell l0 l0 earranging: l A 0 l () A 0
101 Application 3: To measure the internal resistance of a cell Circuit t l l l A Circuit 2 earranging: t l A (2)
102 Application 3: To measure the internal resistance of a cell When switch is CLOSED, circuit 2 has current flow now. When there is current flow, the battery has internal resistance due to the chemical reaction inside the battery. So for circuit 2, t r earranging r t t t t Substitute r (3)
103 Application 3: To measure the internal resistance of a cell Substitute () and (2) into (3): earranging: l l l r 0 c x m y 0 l 0 l r l or l l r 0
104 Example 9 Consider a potentiometer: f a standard battery with an e.m.f. of.086 is used in the circuit, the galvanometer reads zero when the resistance is 36 Ω. f the standard battery is replaced by an unknown e.m.f. the galvanometer reads zero when the resistance is adjusted to 48 Ω. What is the value of the unknown e.m.f.?
105 Example 9 Solution
106 Example 20 n the potentiometer circuit shown below, PQ is a uniform wire of length.0 m and resistance 0.0. is an accumulator of e.m.f. 2.0 and negligible internal resistance. is a 5 resistor and 2 is a 5.0 resistor when S and S 2 open, galvanometer G is balanced when QT is 62.5 cm. When both S and S 2 are closed, the balance length is 0.0 cm. Calculate a. the e.m.f. of cell 2. b. the internal resistance of cell 2.
107 Example 20 Solution
108 Example 20 Solution
109 Example 20 Solution
110 Wheatstone Bridge t is used to measured the unknown resistance of the resistor. Figure below shows the Wheatstone bridge circuit consists of a cell of e.m.f. (accumulator), a galvanometer, know resistances (, 2 and 3 ) and unknown resistance x. The Wheatstone bridge is said to be balanced when no current flows through the galvanometer.
111 Wheatstone Bridge When the Wheatstone Bridge is balanced: AC AD CB DB 2 Potential at C = Potential at D AC AD and BC BD Since =, and 2 2X 23 Dividing gives: X X
112 Application: Metre Bridge The metre bridge is balanced when the jockey J is at such a position on wire AB that there is no current through the galvanometer. X l l 2
113 Example 2 An unknown length of platinum wire mm in diameter is placed as the unknown resistance in a Wheatstone bridge as shown in figure below. esistors and 2 have resistance of 38.0 and 46.0 respectively. Balance is achieved when the switch closed and 3 is Find the length of the platinum wire if its resistivity is 0.6 x 08 m.
114 Example 2 Solution
115 Summary Electric Current Conduction of Electricity dq dt Ohm s Law Electrical Energy W t Drift elocity esistivity Electrical Power v d nae A l P Dependence of esistance on Temperature T T 0 0
116 Summary DirectCurrent Circuit Electromotive Force, nternal esistor & Potential Difference terminal r First Law Kirchhoff s Laws Second Law Potential Divider 2 in out Potentiometer 2 l l 2 esistors Wheatstone Bridge n Series n Parallel X 2 3
117
Chapter 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 informationUNIT 5: Electric Current and DirectCurrent Circuit (D.C.)
UNT 5: Electric Current DirectCurrent Circuit (D.C.) SF07 5. Electric Current, Consider a simple closed circuit consists of wires, a battery a lamp as shown in figure 5.a. F r e E r rea, From the figure,
More informationCURRENT ELECTRICITY The charge flowing any crosssection per unit time in a conductor is called electric current.
CUENT ELECTICITY Important Points:. Electric Current: The charge flowing any crosssection per unit time in a conductor is called electric current. Electric Current I q t. Current Density: a) The current
More information1 Written and composed by: Prof. Muhammad Ali Malik (M. Phil. Physics), Govt. Degree College, Naushera
CURRENT ELECTRICITY Q # 1. What do you know about electric current? Ans. Electric Current The amount of electric charge that flows through a cross section of a conductor per unit time is known as electric
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 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 informationElectricity & Magnetism
Electricity & Magnetism D.C. Circuits Marline Kurishingal Note : This chapter includes only D.C. In AS syllabus A.C is not included. Recap... Electrical Circuit Symbols : Draw and interpret circuit diagrams
More informationChapter 20 Electric Circuits
Chapter 0 Electric Circuits Chevy olt  Electric vehicle of the future Goals for Chapter 9 To understand the concept of current. To study resistance and Ohm s Law. To observe examples of electromotive
More 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 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 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 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 informationElectric Currents. Resistors (Chapters 2728)
Electric Currents. Resistors (Chapters 2728) Electric current I Resistance R and resistors Relation between current and resistance: Ohm s Law Resistivity ρ Energy dissipated by current. Electric power
More informationPHY102 Electricity Course Summary
TOPIC 1 ELECTOSTTICS PHY1 Electricity Course Summary Coulomb s Law The magnitude of the force between two point charges is directly proportional to the product of the charges and inversely proportional
More informationPhysics 142 Steady Currents Page 1. Steady Currents
Physics 142 Steady Currents Page 1 Steady Currents If at first you don t succeed, try, try again. Then quit. No sense being a damn fool about it. W.C. Fields Electric current: the slow average drift of
More informationR R V I R. Conventional Current. Ohms Law V = IR
DC Circuits opics EMF and erminal oltage esistors in Series and in Parallel Kirchhoff s ules EMFs in Series and in Parallel Capacitors in Series and in Parallel Ammeters and oltmeters Conventional Current
More informationCHAPTER: 3 CURRENT ELECTRICITY
CHAPTER: 3 CURRENT ELECTRICITY 1. Define electric current. Give its SI unit. *Current is the rate of flow of electric charge. I (t) = dq dt or I = q t SI unit is ampere (A), 1A = 1C 1s 2. Define current
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 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 informationSPS Presents: A Cosmic Lunch!
SPS Presents: A Cosmic Lunch! Who: Dr. Brown will be speaking about Evolution of the Elements: from Periodic table to Standard Model and Beyond! When: October 7 th at am Where: CP 79 (by the front office)
More informationChapter 27: Current and Resistance
Chapter 7: Current and esistance In this section of the course we will be studying the flow of electric charge, current, in a circuit. We have already seen electric current when we first discussed electric
More 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 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 informationDirect Current (DC) Circuits
Direct Current (DC) Circuits NOTE: There are short answer analysis questions in the Participation section the informal lab report. emember to include these answers in your lab notebook as they will be
More 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 informationDirectCurrent Circuits. Physics 231 Lecture 61
DirectCurrent Circuits Physics 231 Lecture 61 esistors in Series and Parallel As with capacitors, resistors are often in series and parallel configurations in circuits Series Parallel The question then
More informationElectric Currents and Circuits
Nicholas J. Giordano www.cengage.com/physics/giordano Chapter 19 Electric Currents and Circuits Marilyn Akins, PhD Broome Community College Electric Circuits The motion of charges leads to the idea of
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 informationChapter 26 DirectCurrent and Circuits.  Resistors in Series and Parallel  Kirchhoff s Rules  Electric Measuring Instruments  RC Circuits
Chapter 26 DirectCurrent and Circuits  esistors in Series and Parallel  Kirchhoff s ules  Electric Measuring Instruments  C Circuits . esistors in Series and Parallel esistors in Series: V ax I V
More informationChapter 25 Current Resistance, and Electromotive Force
Chapter 25 Current Resistance, and Electromotive Force 1 Current In previous chapters we investigated the properties of charges at rest. In this chapter we want to investigate the properties of charges
More informationPhysics 2B: Review for Celebration #2. Chapter 22: Current and Resistance
Physics 2: eview for Celebration #2 Chapter 22: Current and esistance Current: q Current: I [I] amps (A) 1 A 1 C/s t Current flows because a potential difference across a conductor creates an electric
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 informationAP Physics C. Electric Circuits III.C
AP Physics C Electric Circuits III.C III.C.1 Current, Resistance and Power The direction of conventional current Suppose the crosssectional area of the conductor changes. If a conductor has no current,
More 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 informationBasic Electricity. Unit 2 Basic Instrumentation
Basic Electricity Unit 2 Basic Instrumentation Outlines Terms related to basic electricitydefinitions of EMF, Current, Potential Difference, Power, Energy and Efficiency Definition: Resistance, resistivity
More informationAP Physics C  E & M
AP Physics C  E & M Current and Circuits 20170712 www.njctl.org Electric Current Resistance and Resistivity Electromotive Force (EMF) Energy and Power Resistors in Series and in Parallel Kirchoff's
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 informationBy Mir Mohammed Abbas II PCMB 'A' CHAPTER FORMULAS & NOTES. 1. Current through a given area of a conductor is the net charge passing
Formulae For u CURRENT ELECTRICITY 1 By Mir Mohammed Abbas II PCMB 'A' 1 Important Terms, Definitions & Formulae CHAPTER FORMULAS & NOTES 1. Current through a given area of a conductor is the net charge
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 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 informationPhysics 1214 Chapter 19: Current, Resistance, and DirectCurrent Circuits
Physics 1214 Chapter 19: Current, Resistance, and DirectCurrent Circuits 1 Current current: (also called electric current) is an motion of charge from one region of a conductor to another. Current When
More informationUNIT II CURRENT ELECTRICITY
UNIT II CUENT ELECTICITY Weightage : 07 Marks Electric current; flow of electric charges in a metllic conductor, drift velocity, mobility and their relation with electric current. Ohm s law electrical
More informationCHEM*3440. Current Convention. Charge. Potential Energy. Chemical Instrumentation. Rudimentary Electronics. Topic 3
urrent onvention HEM*3440 hemical nstrumentation Topic 3 udimentary Electronics ONENTON: Electrical current flows from a region of positive potential energy to a region of more negative (or less positive)
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 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 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 informationDC Circuits. Electromotive Force Resistor Circuits. Kirchoff s Rules. RC Circuits. Connections in parallel and series. Complex circuits made easy
DC Circuits Electromotive Force esistor Circuits Connections in parallel and series Kirchoff s ules Complex circuits made easy C Circuits Charging and discharging Electromotive Force (EMF) EMF, E, is the
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 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 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 1402: Lecture 10 Today s Agenda
Physics 1402: Lecture 10 Today s Agenda Announcements: Lectures posted on: www.phys.uconn.edu/~rcote/ HW assignments, solutions etc. Homework #3: On Masterphysics : due Friday at 8:00 AM Go to masteringphysics.com
More information(b) The diagram given below has T2>T1. Explain. Ans.: We know that V IR, T indicates the temperature I 1. (Lower temperature) (Higher Temperature)
BHSEC: 2009 (a) How can a galvanometer be converted into an ammeter of desired range? Explain with the help of diagram. By connecting a low resistance (shunt) in parallel to the galvanometer. As per ohm
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 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 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 informationCURRENT ELECTRICITY MARKS WEIGHTAGE 7 marks
CURRENT ELECTRICITY MARKS WEIGHTAGE 7 marks QUICK REVISION (Important Concepts & Formulas) Electric current The current is defined as the rate of flow of charges across any cross sectional area of a conductor.
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 informationDownloaded from
CLASS XII MLL Questions Current Electricity Q.. The sequence of bands marked on a carbon resistor is red, red. Red silver. What is the value of resistance? Ans: 0 ±0% Q. Does the drift velocity vary with
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 informationCURRENT ELECTRICITY CHAPTER 13 CURRENT ELECTRICITY Qs. Define Charge and Current. CHARGE Definition Flow of electron is known as Charge. It is denoted by Q. Unit Its unit is Coulomb. 1 Coulomb = 10(6)
More informationChapter 26 Current and Resistance
Chapter 26 Current and Resistance Electric Current Although an electric current is a stream of moving charges, not all moving charges constitute an electric current. If there is to be an electric current
More informationPhysics 214 Spring
Lecture 23 March 4 2016 The elation between Voltage Differences V and Voltages V? Current Flow, Voltage Drop on esistors and Equivalent esistance Case 1: Series esistor Combination and esulting Currents
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 informationTridib s Physics Tutorials visit NCERTXII / Unit 03 Current Electricity
CURRENT ELECTRICITY OHM S LAW: Let us consider a conductor through which a current I is flowing and V be the potential difference between its ends,then Ohm s law states that V I or, V = R I..(1) where
More informationKirchhoff's Laws I 2 I 3. junc. loop. loop IR +IR 2 2 V P I V I R R R R R C C C. eff R R R C C C. eff 3.0
V Kirchhoff's Laws junc j 0 1 2 3  V + +V  + loop V j 0 2 2 V P V  + loop eff 1 2 1 1 1 eff 1 2 1 1 1 C C C eff C C C eff 1 2 1 2 3.0 Charges in motion Potential difference V + E Metal wire crosssection
More informationCHAPTER INTRODUCTION TO ELECTRIC CIRCUITS. C h a p t e r INTRODUCTION
C h a p t e r CHAPTE NTODUCTON TO ELECTC CCUTS.0 NTODUCTON This chapter is explaining about the basic principle of electric circuits and its connections. The learning outcome for this chapter are the students
More informationPhysics 169. Luis anchordoqui. Kitt Peak National Observatory. Wednesday, March 8, 17
Physics 169 Kitt Peak National Observatory Luis anchordoqui 1 5.1 Ohm s Law and Resistance ELECTRIC CURRENT is defined as flow of electric charge through a crosssectional area Convention i = dq dt Unit
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 6 DIRECT CURRENT CIRCUITS. Recommended Problems: 6,9,11,13,14,15,16,19,20,21,24,25,26,28,29,30,31,33,37,68,71.
Chapter 6 DRECT CURRENT CRCUTS Recommended Problems: 6,9,,3,4,5,6,9,0,,4,5,6,8,9,30,3,33,37,68,7. RESSTORS N SERES AND N PARALLEL  N SERES When two resistors are connected together as shown we said that
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 informationChapter 27. Circuits
Chapter 27 Circuits 1 1. Pumping Chagres We need to establish a potential difference between the ends of a device to make charge carriers follow through the device. To generate a steady flow of charges,
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 informationELECTRIC CURRENT. Ions CHAPTER Electrons. ELECTRIC CURRENT and DIRECTCURRENT CIRCUITS
LCTRC CURRNT CHAPTR 25 LCTRC CURRNT and DRCTCURRNT CRCUTS Current as the motion of charges The Ampère Resistance and Ohm s Law Ohmic and nonohmic materials lectrical energy and power ons lectrons nside
More informationin series Devices connected in series will have the same amount of charge deposited on each capacitor. But different potential difference. That means
Electric Field Electricity Lecture Series Electric Field: Field an area where any charged object will experience an electric force Kirchoff s Laws The electric field lines around a pair of point charges
More informationECE 1311: Electric Circuits. Chapter 2: Basic laws
ECE 1311: Electric Circuits Chapter 2: Basic laws Basic Law Overview Ideal sources series and parallel Ohm s law Definitions open circuits, short circuits, conductance, nodes, branches, loops Kirchhoff's
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 informationANNOUNCEMENT ANNOUNCEMENT
ANNOUNCEMENT Exam : Tuesday September 25, 208, 8 PM  0 PM Location: Elliott Hall of Music (see seating chart) Covers all readings, lectures, homework from Chapters 2 through 23 Multiple choice (58 questions)
More informationCURRENT ELECTRICITY. Q1. Plot a graph showing variation of current versus voltage for a material.
CURRENT ELECTRICITY QUESTION OF ONE MARK (VERY SHORT ANSWER) Q. Plot a graph showing variation of current versus voltage for a material. Ans. Q. The graph shown in the figure represents a plot of current
More informationM. C. Escher: Waterfall. 18/9/2015 [tsl425 1/29]
M. C. Escher: Waterfall 18/9/2015 [tsl425 1/29] Direct Current Circuit Consider a wire with resistance R = ρl/a connected to a battery. Resistor rule: In the direction of I across a resistor with resistance
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 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 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 informationEngineering Fundamentals and Problem Solving, 6e
Engineering Fundamentals and Problem Solving, 6e Chapter 17 Electrical Circuits Chapter Objectives Compute the equivalent resistance of resistors in series and in parallel Apply Ohm s law to a resistive
More informationNotes on Electricity (Circuits)
A circuit is defined to be a collection of energygivers (batteries) and energytakers (resistors, light bulbs, radios, etc.) that form a closed path (or complete path) through which electrical current
More 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 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 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 informationECE 2100 Circuit Analysis
ECE 2100 Circuit Analysis Lesson 3 Chapter 2 Ohm s Law Network Topology: nodes, branches, and loops Daniel M. Litynski, Ph.D. http://homepages.wmich.edu/~dlitynsk/ esistance ESISTANCE = Physical property
More informationPhysics 1302W.400 Lecture 21 Introductory Physics for Scientists and Engineering II
Physics 1302W.400 Lecture 21 Introductory Physics for Scientists and Engineering II In today s lecture, we will learn to: Calculate the resistance of a conductor depending on the material and shape Apply
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 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 informationPH 2222C Fall Circuits. Lectures Chapter 27 (Halliday/Resnick/Walker, Fundamentals of Physics 8 th edition)
PH 2222C Fall 2012 Circuits Lectures 1112 Chapter 27 (Halliday/Resnick/Walker, Fundamentals of Physics 8 th edition) 1 Chapter 27 Circuits In this chapter we will cover the following topics: Electromotive
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 informationELECTRICITY. Electric Circuit. What do you already know about it? Do Smarty Demo 5/30/2010. Electric Current. Voltage? Resistance? Current?
ELECTRICITY What do you already know about it? Voltage? Resistance? Current? Do Smarty Demo 1 Electric Circuit A path over which electrons travel, out through the negative terminal, through the conductor,
More 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 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 informationKirchhoff's Laws and Circuit Analysis (EC 2)
Kirchhoff's Laws and Circuit Analysis (EC ) Circuit analysis: solving for I and V at each element Linear circuits: involve resistors, capacitors, inductors Initial analysis uses only resistors Power sources,
More informationElectrical Circuits. Sources of Voltage
Electrical Circuits ALESSANDRO VOLTA (17451827) ANDRE MARIE AMPERE (17751836) GEORG SIMON OHM (17891854) POTENTIAL IN VOLTS, CURRENT IN AMPS, RESISTANCE IN OHMS! Sources of Voltage Voltage, also known
More informationElectric Charge. Electric Charge ( q ) unbalanced charges positive and negative charges. n Units Coulombs (C)
Electric Charge Electric Charge ( q ) unbalanced charges positive and negative charges n Units Coulombs (C) Electric Charge How do objects become charged? Types of materials Conductors materials in which
More 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 information