# Chapter 17. Current and Resistance. Sections: 1, 3, 4, 6, 7, 9

Size: px
Start display at page:

Download "Chapter 17. Current and Resistance. Sections: 1, 3, 4, 6, 7, 9"

Transcription

1 Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9

2 Equations: 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 V C V Q Energy = = = Parallel capacitors: V = V 1 = V 2 C eq = C 1 + C 2 Series capacitors: C C C V V V eq + = + = d A C o =ε V Q C r q q k q V PE e = = r q k V e = Φ E = E A cos θ o E Q ε = Φ C = κc o = κε o (A/d)

3 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 flows through a cross section of the conductor Charges flowing perpendicularly to a surface of area A The SI unit of current is Ampere (A) 1 A = 1 C/s

4 Electric Current The direction of current flow is the direction positive charge would flow This is known as conventional current flow In a common conductor, such as copper, the current is due to the motion of the negatively charged electrons It is common to refer to a moving charge as a mobile charge carrier A charge carrier can be positive or negative

5 QUICK QUIZ 17.1 Consider positive and negative charges moving horizontally through the four regions in Figure Rank the currents in these four regions, from lowest to highest.

6 QUICK QUIZ 17.1 ANSWER d, b = c, a. The current in (d) is equivalent to two positive charges moving to the left. Parts (b) and (c) each represent four charges moving in the same direction because negative charges moving to the left are equivalent to positive charges moving to the right. The current in (a) is equivalent to five positive charges moving to the right.

7 Charge Carrier Motion in a The zig-zag black line represents the motion of charge carrier in a conductor The sharp changes in direction are due to collisions The net motion of electrons is opposite the direction of the electric field Conductor

8 Electrons in a Circuit The drift speed is much smaller than the average speed between collisions When a circuit is completed, the electric field travels with a speed close to the speed of light Although the drift speed is on the order of 10-4 m/s the effect of the electric field is felt on the order of 10 8 m/s

9 Current and Drift Speed The total charge is the number of carriers times the charge per carrier, q Q = (n A x) q n is the charge density The drift speed, v d, is the speed at which the carriers move v d = x / t Q = (n A v d t) q I = Q/ t = nqv d A

10 Meters in a Circuit -- Ammeter An ammeter is used to measure current In line with the bulb, all the charge passing through the bulb also must pass through the meter

11 Meters in a Circuit -- Voltmeter A voltmeter is used to measure voltage (potential difference) Connects to the two ends of the bulb

12 QUICK QUIZ 17.2 Look at the four circuits shown below and select those that will light the bulb.

13 QUICK QUIZ 17.2 ANSWER (c), (d). Neither circuit (a) nor circuit (b) applies a difference in potential across the bulb. Circuit (a) has both lead wires connected to the same battery terminal. Circuit (b) has a low resistance path (a short ) between the two battery terminals as well as between the bulb terminals.

14 Resistance In a conductor, the voltage applied across the ends of the conductor is proportional to the current through the conductor The constant of proportionality is the resistance of the conductor R = V I

15 Resistance Units of resistance are ohms (Ω) 1 Ω = 1 V / A Resistance in a circuit arises due to collisions between the electrons carrying the current with the fixed atoms inside the conductor

16 Ohm s Law Experiments show that for many materials, including most metals, the resistance remains constant over a wide range of applied voltages or currents This statement has become known as Ohm s Law V = I R Ohm s Law is an empirical relationship that is valid only for certain materials Materials that obey Ohm s Law are said to be ohmic

17 Ohm s Law An ohmic device The resistance is constant over a wide range of voltages The relationship between current and voltage is linear The slope is related to the resistance

18 Non-ohmic materials are those whose resistance changes with voltage or current Ohm s Law The current-voltage relationship is nonlinear A diode is a common example of a nonohmic device

19 QUICK QUIZ 17.3 In the figure below, does the resistance of the diode (a) increase or (b) decrease as the positive voltage V increases?

20 QUICK QUIZ 17.3 ANSWER (b). The slope of the line tangent to the curve at a point is the reciprocal of the resistance at that point. Note that as V increases, the slope (and hence 1/R) increases. Thus, the resistance decreases.

21 Resistivity The resistance of an ohmic conductor is proportional to its length, L, and inversely proportional to its crosssectional area, A R = ρ L A ρ is the constant of proportionality and is called the resistivity of the material

22 Fig. 17.T1, p.538

23 Temperature Variation of Resistivity For most metals, resistivity increases with increasing temperature With a higher temperature, the metal s constituent atoms vibrate with increasing amplitude The electrons find it more difficult to pass the atoms

24 Temperature Variation of Resistivity For most metals, resistivity increases approximately linearly with temperature over a limited temperature range ρ = ρ o [ 1+ α(t To )] ρ o is the resistivity at some reference temperature T o T o is usually taken to be 20 C α is the temperature coefficient of resistivity

25 Fig. 17.T1, p.538

26 Temperature Variation of Resistance Since the resistance of a conductor with uniform cross sectional area is proportional to the resistivity, you can find the effect of temperature on resistance R = R o [1+ α(t T o )]

27 Fig , p.542

28 Electrical Energy and Power In a circuit, as a charge moves through the battery, the electrical potential energy of the system is increased by Q V The chemical potential energy of the battery decreases by the same amount As the charge moves through a resistor, it loses this potential energy during collisions with atoms in the resistor The temperature of the resistor will increase

29 Electrical Energy and Power The rate at which the energy is lost is the power Q P = V = I V t From Ohm s Law, alternate forms of power are (for Ohmic devices only!) P = I R = ( 2 V) R 2

30 Electrical Energy and Power The SI unit of power is Watt (W) I must be in Amperes, R in ohms and V in Volts The unit of energy used by electric companies is the kilowatt-hour This is defined in terms of the unit of power and the amount of time it is supplied 1 kwh = 3.60 x 10 6 J

31 QUICK QUIZ 17.5 A voltage V is applied across the ends of a nichrome heater wire having a cross-sectional area A and length L. The same voltage is applied across the ends of a second heater wire having a cross-sectional area A and length 2L. Which wire gets hotter? (a) the shorter wire, (b) the longer wire, or (c) not enough information to say.

32 QUICK QUIZ 17.5 ANSWER (a). The resistance of the shorter wire is half that of the longer wire. The power dissipated, P = ( V) 2 /R, (and hence the rate of heating) will be greater for the shorter wire. Consideration of the expression P = I 2 R might initially lead one to think that the reverse would be true. However, one must realize that the currents will not be the same in the two wires.

33 QUICK QUIZ 17.6 For the two resistors shown here, rank the currents at points a through f, from largest to smallest. P = I R = ( 2 V) R 2

34 QUICK QUIZ 17.6 ANSWER I a = I b > I c = I d > I e = I f. Charges constituting the current I a leave the positive terminal of the battery and then split to flow through the two bulbs; thus, I a = I c + I e. Because the potential difference V is the same across the two bulbs and because the power delivered to a device is P = I( V), the 60 W bulb with the higher power rating must carry the greater current. Because charge does not accumulate in the bulbs, all the charge flowing into a bulb from the left has to flow out on the right; consequently I c = I d and I e = I f. The two currents leaving the bulbs recombine to form the current back into the battery, I f + I d = I b.

35 QUICK QUIZ 17.7 Two resistors, A and B, are connected across the same potential difference. The resistance of A is twice that of B. (a) Which resistor dissipates more power? (b) Which carries the greater current?

36 QUICK QUIZ 17.7 ANSWER B, B. Because the voltage across each resistor is the same, and the rate of energy delivered to a resistor is P = ( V) 2 /R, the resistor with the lower resistance exhibits the higher rate of energy transfer. In this case, the resistance of B is smaller than that for A and thus B dissipates more power. Furthermore, because P = I( V), the current carried by B is larger than that of A.

37 Problems: 14, 20, 24, 34, 44, 46 Look for tips at

### 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

### 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

### 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

### and 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

### Chapter 17. Current and Resistance

Chapter 17 Current and Resistance Electric Current The current is the rate at which the charge flows through a surface Look at the charges flowing perpendicularly through a surface of area A I av The SI

### 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

### Chapter 17 Current and Resistance

Chapter 17 Current and Resistance Current Practical applications were based on static electricity. A steady source of electric current allowed scientists to learn how to control the flow of electric charges

### Chapter 27. Current And Resistance

Chapter 27 Current And Resistance Electric Current Electric current is the rate of flow of charge through some region of space The SI unit of current is the ampere (A) 1 A = 1 C / s The symbol for electric

### 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

### Chapter 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

### Chapter 27 Current and resistance

27.1 Electric Current Chapter 27 Current and resistance 27.2 Resistance 27.3 A Model for Electrical Conduction 27.4 Resistance and Temperature 27.6 Electrical Power 2 27.1 Electric Current Consider a system

### Chapter 27. Current And Resistance

Chapter 27 Current And Resistance Electric Current Electric current is the rate of flow of charge through some region of space The SI unit of current is the ampere (A) 1 A = 1 C / s The symbol for electric

### Chapter 27. Current and Resistance

Chapter 27 Current and Resistance Electric Current Most practical applications of electricity deal with electric currents. The electric charges move through some region of space. The resistor is a new

### Chapter 27. Current and Resistance

Chapter 27 Current and Resistance Electric Current Most practical applications of electricity deal with electric currents. The electric charges move through some region of space. The resistor is a new

### 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

### 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

### University Physics (PHY 2326)

Chapter 25 University Physics (PHY 2326) Lecture 7 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm

### General Physics (PHY 2140)

General Physics (PHY 2140) Lecture 7 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm s law http://www.physics.wayne.edu/~apetrov/phy2140/

### 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

### Chapter 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

### 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

### 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

### Chapter 3: Electric Current and Direct-Current Circuit

Chapter 3: Electric Current and Direct-Current Circuit n this chapter, we are going to discuss both the microscopic aspect and macroscopic aspect of electric current. Direct-current is current that flows

### 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 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

### 6. In a dry cell electrical energy is obtained due to the conversion of:

1. If a wire of uniform area of cross section is cut into two halves (equal in size), the resistivity of each part will be: a) Halved. b) Doubled. c) Becomes four times its initial value. d) Remains the

### 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.

### 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,

### Chapter 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

### 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 (primarily, in metals)

Electric currents (primarily, in metals) Benjamin Franklin was experimenting electricity in the mid- XVIII Century. Nobody knew if it was the positive charges or negative charges carrying the current through

### 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 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

### 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

### Look over Chapter 26 sections 1-7 Examples 3, 7. Look over Chapter 18 sections 1-5, 8 over examples 1, 2, 5, 8, 9,

Look over Chapter 26 sections 1-7 Examples 3, 7 Look over Chapter 18 sections 1-5, 8 over examples 1, 2, 5, 8, 9, 1)How to find a current in a wire. 2)What the Current Density and Draft Speed are. 3)What

### 3 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

### 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.

### SIMPLE 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,

### 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

### ELECTRICITY. 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,

### 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

### 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

### Ch. 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 Time-Dependent

### Closed 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

### Q-2 How many coulombs of charge leave the power supply during each second?

Part I - Circuit Elements in Series In Figure 1 at the right circuit elements #1, #2, #3 (in this case light bulbs) are said to be connected "IN SERIES". That is, they are connected in a series one right

### 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

### DEVIL PHYSICS THE BADDEST CLASS ON CAMPUS IB PHYSICS

DEL PHYSCS THE BADDEST CLASS ON CAMPUS B PHYSCS TSOKOS LESSON 5-4: ELECTRC CURRENT AND ELECTRC RESSTANCE Reading Activity Questions? Objectives By the end of this class you should be able to: Q State the

### 1 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

### Nama :.. Kelas/No Absen :

Nama :.. Kelas/No Absen : TASK 2 : CURRENT AND RESISTANCE 1. A car battery is rated at 80 A h. An ampere-hour is a unit of: A. power B. energy C. current D. charge E. force 2. Current has units: A. kilowatt-hour

### 2. Basic Components and Electrical Circuits

1 2. Basic Components and Electrical Circuits 2.1 Units and Scales The International System of Units (SI) defines 6 principal units from which the units of all other physical quantities can be derived

### General Physics (PHY 2140)

General Physics (PHY 2140) Lecture 4 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm s law resistivity

### PH 102 Exam I N N N N. 3. Which of the following is true for the electric force and not true for the gravitational force?

Name Date INSTRUCTIONS PH 102 Exam I 1. nswer all questions below. ll problems have equal weight. 2. Clearly mark the answer you choose by filling in the adjacent circle. 3. There will be no partial credit

### Current 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

### 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

### 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

### Let s go to something more concrete

Let s go to something more concrete Let me define an electric current Whenever charges of like sign are moving, an electric current exists Suppose I have a surface A with charges (assume + because of Franklin

### For an electric current to flow between two points, two conditions must be met.

ELECTROSTATICS LAB Electric Circuits For an electric current to flow between two points, two conditions must be met. 1. There must be a conducting path between the points along which the charges can move.

### Electromagnetism Checklist

Electromagnetism Checklist Elementary Charge and Conservation of Charge 4.1.1A Convert from elementary charge to charge in coulombs What is the charge in coulombs on an object with an elementary charge

### Chapter 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.

### 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

### General 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 17-18 1 Department

### Electric Currents and Simple Circuits

-1 Electric Currents and Simple Circuits Electrons can flow along inside a metal wire if there is an E-field present to push them along ( F= qe). The flow of electrons in a wire is similar to the flow

### 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

### 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

### RECALL?? 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

### PHYSICS FORM 5 ELECTRICAL QUANTITES

QUANTITY SYMBOL UNIT SYMBOL Current I Amperes A Voltage (P.D.) V Volts V Resistance R Ohm Ω Charge (electric) Q Coulomb C Power P Watt W Energy E Joule J Time T seconds s Quantity of a Charge, Q Q = It

### 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

### Circuits-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?

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.

### Electrical Circuits. Sources of Voltage

Electrical Circuits ALESSANDRO VOLTA (1745-1827) ANDRE MARIE AMPERE (1775-1836) GEORG SIMON OHM (1789-1854) POTENTIAL IN VOLTS, CURRENT IN AMPS, RESISTANCE IN OHMS! Sources of Voltage Voltage, also known

### Coulomb s constant k = 9x10 9 N m 2 /C 2

1 Part 2: Electric Potential 2.1: Potential (Voltage) & Potential Energy q 2 Potential Energy of Point Charges Symbol U mks units [Joules = J] q 1 r Two point charges share an electric potential energy

### Physics 1B Electricity & Magnetism. Frank Wuerthwein (Prof) Edward Ronan (TA) UCSD

Physics 1B Electricity & Magnetism Frank Wuerthwein (Prof) Edward Ronan (TA) UCSD Quiz 1 Quiz 1A and it s answer key is online at course web site. http://hepuser.ucsd.edu/twiki2/bin/view/ UCSDTier2/Physics1BWinter2012

### From last time. Today: More on electric potential and connection to E-field How to calculate E-field from V Capacitors and Capacitance

From last time More on electric potential and connection to Efield How to calculate Efield from V Capacitors and Capacitance Today: More on Capacitors and Capacitance Energy stored in Capacitors Current

### Electric 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

### 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

### Current and Resistance

Chapter 26 Current and Resistance Copyright 26-1 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

### 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

### 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,

### Test Review Electricity

Name: Date: 1. An operating television set draws 0.71 ampere of current when connected to a 120-volt outlet. Calculate the time it takes the television to consume 3.0 10 5 joules of electric energy. [Show

### Chapter 1 The Electric Force

Chapter 1 The Electric Force 1. Properties of the Electric Charges 1- There are two kinds of the electric charges in the nature, which are positive and negative charges. - The charges of opposite sign

### 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

### Direct 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

### 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

### Topic 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

### 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,

### 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:

### Ohm s Law Book page Syllabus 2.10

Ohm s Law Book page 85 87 Syllabus 2.10 What s wrong with this circuit diagram? Task 2 Sketch a simple series circuit containing a cell and a bulb. On your circuit diagram, show an ammeter and voltmeter

### 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

### (b) State the relation between work, charge and potential difference for an electric circuit.

Question Bank on Ch-Electricity 1. (a) Define the S.I unit of potential difference. (b) State the relation between work, charge and potential difference for an electric circuit. Calculate the potential

### CLASS X- ELECTRICITY

Conductor- Insulator: Materia Materials through which electric current cannot pass are called insulators. Electric Circuit: A continuous a CLASS X- ELECTRICITY als through which electric current can pass

### 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

### Chapter 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

### Exam 1--PHYS 202--Spring 2013

Name: Class: Date: Exam 1--PHYS 202--Spring 2013 Multiple Choice Identify the choice that best completes the statement or answers the question 1 A metallic object holds a charge of 38 10 6 C What total

### 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 3. Chapter 3

Chapter 3 Review of V, I, and R Voltage is the amount of energy per charge available to move electrons from one point to another in a circuit and is measured in volts. Current is the rate of charge flow

### Physics 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

### PHYSICS. Chapter 27 Lecture FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E RANDALL D. KNIGHT

PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 27 Lecture RANDALL D. KNIGHT Chapter 27 Current and Resistance IN THIS CHAPTER, you will learn how and why charge moves through a wire

### Handout 5: Current and resistance. Electric current and current density

1 Handout 5: Current and resistance Electric current and current density Figure 1 shows a flow of positive charge. Electric current is caused by the flow of electric charge and is defined to be equal to

### 8. Electric circuit: The closed path along which electric current flows is called an electric circuit.

GIST OF THE LESSON 1. Positive and negative charges: The charge acquired by a glass rod when rubbed with silk is called positive charge and the charge acquired by an ebonite rod when rubbed with wool is