# Chapter 21 Electric Current and Direct- Current Circuits

Size: px
Start display at page:

Transcription

1 Chapter 21 Electric Current and Direct- Current Circuits

2 Units of Chapter 21 Electric Current Resistance and Ohm s Law Energy and Power in Electric Circuits Resistors in Series and Parallel Kirchhoff s Rules Circuits Containing Capacitors RC Circuits Ammeters and Voltmeters

3 HW # 5 Pg : # 7, 8, 11, 19, 22, 28, 32, 44, 49, 73, 78 PHYS Due on Thursday, Oct. 10 PHYS Due on Thursday, Oct. 10

4 Practical resistors:

5 Example # 4 When a potential difference of 18 V is applied to a given wire, it conducts 0.35 A of current. What is the resistance of the wire?

6 Resistance and Ohm s Law Two wires of the same length and diameter will have different resistances if they are made of different materials. This property of a material is called the resistivity.

7 Resistance and Ohm s Law The difference between insulators, semiconductors, and conductors can be clearly seen in their resistivities:

8 Resistance and Ohm s Law In general, the resistance of materials goes up as the temperature goes up, due to thermal effects. This property can be used in thermometers. Resistivity decreases as the temperature decreases, but there is a certain class of materials called superconductors in which the resistivity drops suddenly to zero at a finite temperature, called the critical temperature T C.

9 Example # 5 Nichrome is a nickel chromium alloy used in heating applications like electric toasters, because it has a relatively high resistivity and heats up when current passes through it. Suppose you have a nichrome wire 0.20 mm in diameter and 75 cm long. ( a ) What s its resistance? ( b) Find the current when a potential difference of 120 V is connected across the wire s ends.

10 Energy and Power in Electric Circuits When a charge moves across a potential difference, its potential energy changes: Therefore, the power it takes to do this is

11 Energy and Power in Electric Circuits In materials for which Ohm s law holds, the power can also be written: This power mostly becomes heat inside the resistive material.

12 Example # 6 (Your turn) Consider a 60 W light bulb, connected to a 120 V voltage source. What is the current passing through the wire in the bulb? (A) 0.5 A (B) 1.0 A (C) 2.0 A (D) 240 A What is the resistance of the wire in the bulb? (A) 0.5 W (B) 1.0 W (C) 2.0 W (D) 240 W

13 What is the current passing through the wire in the bulb? A A A A

14 What is the resistant of the wire in the bulb? A A A A

15 Conceptual Checkpoint 21-2 A battery that produces a potential difference V is connected to a 5-W lightbulb. Later the 5-W lightbult is replaced with a 10- W lightbulb. (a) In which case does the battery supply more current? W W

16 Conceptual Checkpoint 21-2 A battery that produces a potential difference V is connected to a 5-W lightbulb. Later the 5-W lightbult is replaced with a 10- W lightbulb. (b) Which lightbulb has the greater resistance? W W

17 Example # 7 pb. # 29 a) Find the power dissipated in a 25-Ω electric heater connected to a 120- V outlet kw kw kw kw

18 Energy Use: Energy and Power in Electric Circuits When the electric company sends you a bill, your usage is quoted in kilowatt-hours (kwh). They are charging you for energy use, and kwh are a measure of energy.

19 Example # 8 Electric utilities measure energy in kilowatt-hours (kwh), where 1 kwh is the energy consumed if you use energy at the rate of 1 kw for 1 hour. If your monthly electric bill (30 days) is \$100 and you pay 12.5c/kWh, what s your home s average power consumption and average current, assuming a 240-V potential difference between the wires supplying your home? kw kw kw kw

20 Example # 8 Electric utilities measure energy in kilowatt-hours (kwh), where 1 kwh is the energy consumed if you use energy at the rate of 1 kw for 1 hour. If your monthly electric bill (30 days) is \$100 and you pay 12.5c/kWh, what s your home s average power consumption and average current, assuming a 240-V potential difference between the wires supplying your home? Response for 2 nd question A A A A

21 Example # 9 Several male students in the same dorm room want to dry their hair. Having taken PHYS 1402 at UTPA, they have set their hair dryers to the low, 1000-W settings. Assuming a standard 120-V how many hair dryers can they operate simultaneously without tripping the 20-A circuit breaker? A A A A

22 Resistors in Series Resistors connected end to end are said to be in series. They can be replaced by a single equivalent resistance without changing the current in the circuit.

23 Resistors in Series Since the current through the series resistors must be the same in each, and the total potential difference is the sum of the potential differences across each resistor, we find that the equivalent resistance is:

24 Resistors in Series The same current ( I ) must flow through each of the resistors: I eq = I 1 = I 2 = I 3 Total potential difference from point A to point B must be the emf of the battery ε V eq = ε = V 1 + V 2 + V 3. ε = I R eq

25 Resistors in Series

26 Example # 10 Two resistors, one having half the resistance of the other, are connected to a battery as shown on the white board. What is the voltage across the bigger resistor? 1. A 2. B 3. C 4. D V b V b 3V b 2V b / 2 / 3 / 2 / 3

27 Example # 11 Two resistors, one having half the resistance of the other, are connected to an emf battery as shown on the board. What is the emf of the battery? 1. A 2. B 3. C 4. D IR / 2 IR / 3 3IR / 2 2IR / 3

28 Resistors Parallel Resistors are in parallel when they are across the same potential difference; they can again be replaced by a single equivalent resistance:

29 Resistors in Parallel Using the fact that the potential difference across each resistor is the same, and the total current is the sum of the currents in each resistor, we find: Note that this equation gives you the inverse of the resistance, not the resistance itself!

30 Resistors in Parallel The potential difference across each resistor will be the same. V eq = ε = V 1 = V 2 = V 3 The equivalent current will be the sum of all the currents. I eq = I 1 + I 2 + I 3

31 Example # 12 Two resistors are connected ( a ) in parallel, and ( b ) in series, to a 24.0 V battery. See the diagraph on the white board. What is the current through each resistor and what is the equivalent resistance of each circuit?

32 Resistors Parallel If a circuit is more complex, start with combinations of resistors that are either purely in series or in parallel. Replace these with their equivalent resistances; as you go on you will be able to replace more and more of them.

33 Kirchhoff s Rules More complex circuits cannot be broken down into series and parallel pieces. For these circuits, Kirchhoff s rules are useful. The junction rule is a consequence of charge conservation; the loop rule is a consequence of energy conservation.

34 Kirchhoff s Rules The junction rule: At any junction, the current entering the junction must equal the current leaving it.

35 Kirchhoff s Rules The loop rule: The algebraic sum of the potential differences around a closed loop must be zero (it must return to its original value at the original point).

36 Using Kirchhoff s rules: Kirchhoff s Rules The variables for which you are solving are the currents through the resistors. You need as many independent equations as you have variables to solve for. You will need both loop and junction rules.

37 Circuits Containing Capacitors Capacitors can also be connected in series or in parallel. When capacitors are connected in parallel, the potential difference across each one is the same.

38 21-6 Circuits Containing Capacitors Therefore, the equivalent capacitance is the sum of the individual capacitances:

39 21-6 Circuits Containing Capacitors Capacitors connected in series do not have the same potential difference across them, but they do all carry the same charge. The total potential difference is the sum of the potential differences across each one.

40 21-6 Circuits Containing Capacitors Therefore, the equivalent capacitance is Note that this equation gives you the inverse of the capacitance, not the capacitance itself! Capacitors in series combine like resistors in parallel, and vice versa.

41 21-7 RC Circuits In a circuit containing only batteries and capacitors, charge appears almost instantaneously on the capacitors when the circuit is connected. However, if the circuit contains resistors as well, this is not the case.

42 21-7 RC Circuits Using calculus, it can be shown that the charge on the capacitor increases as: Here, τ is the time constant of the circuit: And is the final charge on the capacitor, Q.

43 21-7 RC Circuits Here is the charge vs. time for an RC circuit:

44 21-7 RC Circuits It can be shown that the current in the circuit has a related behavior:

45 21-8 Ammeters and Voltmeters An ammeter is a device for measuring current, and a voltmeter measures voltages. The current in the circuit must flow through the ammeter; therefore the ammeter should have as low a resistance as possible, for the least disturbance.

46 21-8 Ammeters and Voltmeters A voltmeter measures the potential drop between two points in a circuit. It therefore is connected in parallel; in order to minimize the effect on the circuit, it should have as large a resistance as possible.

47 Summary of Chapter 21 Electric current is the flow of electric charge. Unit: ampere 1 A = 1 C/s A battery uses chemical reactions to maintain a potential difference between its terminals. The potential difference between battery terminals in ideal conditions is the emf. Work done by battery moving charge around circuit:

48 Summary of Chapter 21 Direction of current is the direction positive charges would move. Ohm s law: Relation of resistance to resistivity: Resistivity generally increases with temperature. The resistance of a superconductor drops suddenly to zero at the critical temperature, T C.

49 Summary of Chapter 21 Power in an electric circuit: If the material obeys Ohm s law, Energy equivalent of one kilowatt-hour: Equivalent resistance for resistors in series:

50 Summary of Chapter 21 Inverse of the equivalent resistance of resistors in series: Junction rule: All current that enters a junction must also leave it. Loop rule: The algebraic sum of all potential charges around a closed loop must be zero.

51 Summary of Chapter 21 Equivalent capacitance of capacitors connected in parallel: Inverse of the equivalent capacitance of capacitors connected in series:

52 Charging a capacitor: Summary of Chapter 21 Discharging a capacitor:

53 Summary of Chapter 21 Ammeter: measures current. Is connected in series. Resistance should be as small as possible. Voltmeter: measures voltage. Is connected in parallel. Resistance should be as large as possible.

### Lecture 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

### Chapter 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

### Chapter 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

### General Physics (PHYS )

General Physics (PHYS ) Chapter 21-22 Electricity and Magnetism Resistors in series and parallel Kirchoff s rules Magnetism Magnets Announcement Exam: Question # 11 & Last problem Science FunLand Volunteer

### physics 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

### Physics 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

### Chapter 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

### What 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

### physics 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.

### Chapter 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

### Electric 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

### 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

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

### Direct 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

### AP 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,

### Chapter 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

### Chapter 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

### M. 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

### ELECTRICITY & 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

### Electric 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

### Chapter 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.

### Physics 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

### Electric 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

### Chapter 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

### Chapter 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

### DC 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

### CHAPTER 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

### Electric 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

### Class 8. Resistivity and Resistance Circuits. Physics 106. Winter Press CTRL-L to view as a slide show. Class 8. Physics 106.

and Circuits and Winter 2018 Press CTRL-L to view as a slide show. Last time we learned about Capacitance Problems Parallel-Plate Capacitors Capacitors in Circuits Current Ohm s Law and Today we will learn

### Lecture #3. Review: Power

Lecture #3 OUTLINE Power calculations Circuit elements Voltage and current sources Electrical resistance (Ohm s law) Kirchhoff s laws Reading Chapter 2 Lecture 3, Slide 1 Review: Power If an element is

### Electric 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*

### Resistivity 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

### Current 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 2-1 Electric current 2-2

### Insulators 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

### Clicker 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

### Physics 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

### ELECTRICITY UNIT REVIEW

ELECTRICITY UNIT REVIEW S1-3-04: 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

### Physics 212 Midterm 2 Form A

1. A wire contains a steady current of 2 A. The charge that passes a cross section in 2 s is: A. 3.2 10-19 C B. 6.4 10-19 C C. 1 C D. 2 C E. 4 C 2. In a Physics 212 lab, Jane measures the current versus

### Electric 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

### R 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

### Chapter 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

### Static 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

### Exercise 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.

### Chapter 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

### Chapter 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

### Electrodynamics. 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

### Electricity Test Review

Electricity Test Review Definitions; Series Circuit, Parallel Circuit, Equivalent Resistance, Fuse, Circuit Breaker, kilowatt hour, load, short circuit, dry cell, wet cell, fuel cells, solar cells, fossil

### Version 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

### Electric 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

### 52 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

### PHYSICS 570 Master's of Science Teaching. Instructor Richard Sonnenfeld

1 PHYSICS 570 Master's of Science Teaching 1 Electricity Lecture 10 Current, Power, Resistance, and Ohm's Law. Instructor Richard Sonnenfeld mpsonnenfeld@gmail.com 575 835 6434 Big ideas If you know Voltage,

### Chapter 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:

### Parallel Resistors (32.6)

Parallel Resistors (32.6) Resistors connected at both ends are called parallel resistors Neil Alberding (SFU Physics) Physics 121: Optics, Electricity & Magnetism Spring 2010 1 / 1 Parallel Resistors (32.6)

### Chapter 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

### Electron Theory of Charge. Electricity. 1. Matter is made of atoms. Refers to the generation of or the possession of electric charge.

Electricity Refers to the generation of or the possession of electric charge. There are two kinds of electricity: 1. Static Electricity the electric charges are "still" or static 2. Current Electricity

### Electric 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

### Parallel Resistors (32.6)

Parallel Resistors (32.6) Resistors connected at both ends are called parallel resistors The important thing to note is that: the two left ends of the resistors are at the same potential. Also, the two

### 1) Two lightbulbs, one rated 30 W at 120 V and another rated 40 W at 120 V, are arranged in two different circuits.

1) Two lightbulbs, one rated 30 W at 120 V and another rated 40 W at 120 V, are arranged in two different circuits. a. The two bulbs are first connected in parallel to a 120 V source. i. Determine the

Forces Read Chapter 7; pages: 191-221 Objectives: - Describe how electrical charges exert forces on each other; Compare the strengths of electric and gravitational forces; Distinguish between conductors

### 10/14/2018. 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,

### Physics 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

Superconductors 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

### Tactics 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

### Unit 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

### Lecture (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

### College Physics B - PHY2054C

Power College - PHY2054C and 09/15/2014 My Office Hours: Tuesday 10:00 AM - Noon 206 Keen Building PHY2054C Power First Mini-Exam this week on Wednesday!! Location: UPL 101, 10:10-11:00 AM Exam on chapters

### Electricity. Prepared by Juan Blázquez, Alissa Gildemann. Electric charge is a property of all objects. It is responsible for electrical phenomena.

Unit 11 Electricity 1. Electric charge Electric charge is a property of all objects. It is responsible for electrical phenomena. Electrical phenomena are caused by the forces of attraction and repulsion.

### 12/2/2018. 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

### AC 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

### A 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

### Electromotive 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,

### Question 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

### Electricity & 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

### Circuits. 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:

### Current 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

### EXPERIMENT 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

### 1. What is heating effect of current? What is its cause?

GRADE: X PHYSICS (ELECTRICITY) DOMESTIC ELECTRIC CIRCUITS: SERIES OR PARALLEL Disadvantages of series circuits for domestic wiring : In series circuit, if one electrical appliance stops working, due to

### Capacitance, Resistance, DC Circuits

This test covers capacitance, electrical current, resistance, emf, electrical power, Ohm s Law, Kirchhoff s Rules, and RC Circuits, with some problems requiring a knowledge of basic calculus. Part I. Multiple

### Electricity

Electricity Electric Charge There are two fundamental charges in the universe. Positive (proton) has a charge of +1.60 x 10-19 C Negative (electron) has a charge of 1.60 x 10-19 C There is one general

### Circuits. 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

### Chapter 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

### Section 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

### LABORATORY 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

### Electricity. dronstudy.com

Electricity Electricity is a basic part of our nature and it is one of our most widely used forms of energy. We use electricity virtually every minute of every day for example in lighting, heating, refrigeration,

### What is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another.

Electricity What is electricity? Charges that could be either positive or negative and that they could be transferred from one object to another. What is electrical charge Protons carry positive charges

### Chapter 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

### Chapter 26 Direct-Current and Circuits. - Resistors in Series and Parallel - Kirchhoff s Rules - Electric Measuring Instruments - R-C Circuits

Chapter 26 Direct-Current 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

### This week. 3/23/2017 Physics 214 Summer

This week Electrical Circuits Series or parallel that s the question. Current, Power and Energy Why does my laptop battery die? Transmission of power to your home Why do we have big transmission towers?

### This week. 6/2/2015 Physics 214 Summer

This week Electrical Circuits Series or parallel that s the question. Current, Power and Energy Why does my laptop battery die? Transmission of power to your home Why do we have big transmission towers?

### AP 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

### Exam 1--PHYS 202--S12

ame: Exam 1--PHYS 202--S12 Multiple Choice Identify the choice that best completes the statement or answers the question 1 Which of these statements is true about charging by induction? a it can only occur

### Review. Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

Review Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. When more devices are added to a series circuit, the total circuit resistance: a.

### Chapter 23 Revision problem. While we are waiting, please try problem 14 You have a collection of six 1kOhm resistors.

Chapter 23 Revision problem While we are waiting, please try problem 14 You have a collection of six 1kOhm resistors. 1 Electric Circuits Elements of a circuit Circuit topology Kirchhoff s law for voltage

### Name: 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

### Flow 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

### ELECTRICITY. 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

### Chapter 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

### Chapter 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

### Circuits. 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