# General Physics (PHY 2140)

Size: px
Start display at page:

Transcription

1 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 Chapter

2 Reminder (for those who don t read syllabus) Reading Quizzes (bonus 5%): It is important for you to come to class prepared, i.e. be familiar with the material to be presented. To test your preparedness, a simple five-minute quiz, testing your qualitative familiarity with the material to be discussed in class, will be given at the beginning of some of the classes. No make-up reading quizzes will be given. There could be one today but then again 2

3 Lightning Review Last lecture: 1. Capacitance and capacitors Q C = V A Parallel-plate capacitor C = ε0 d Combinations of capacitors Ceq = C1 C2... Parallel Series =... Energy stored in a capacitor Ceq C1 C2 2 1 Q 1 U = QV = = CV 2 2C 2 Review Problem: Consider an isolated simple parallel-plate capacitor whose plates are given equal and opposite charges and are separated by a distance d. Suppose the plates are pulled apart until they are separated by a distance D>d. The electrostatic energy stored in a capacitor is a. greater then b. the same as c. smaller then before the plates were pulled apart. 3 2

4 16.10 Capacitors with dielectrics A dielectrics is an insulating material (rubber, glass, etc.) Consider an insolated, charged capacitor Q Q Q Q Insert a dielectric V 0 V Notice that the potential difference decreases (k = V 0 /V) Since charge stayed the same (Q=Q 0 ) capacitance increases C Q Q κq = = = = V V κ V 0 0 κc 0 dielectric constant: k = C/C 0 Dielectric constant is a material property 4

5 Capacitors with dielectrics - notes Capacitance is multiplied by a factor k when the dielectric fills the region between the plates completely E.g., for a parallel-plate plate capacitor A C = κε 0 d The capacitance is limited from above by the electric discharge that can occur through the dielectric material separating the plates In other words, there exists a maximum of the electric field, sometimes called dielectric strength,, that can be produced in the dielectric before it breaks down 5

6 Dielectric constants and dielectric strengths of various materials at room temperature Material Vacuum Dielectric constant, k 1.00 Dielectric strength (V/m) -- Air Water Fused quartz For a more complete list, see Table

7 Example Take a parallel plate capacitor whose plates have an area of 2.0 m 2 and are separated by a distance of 1mm. The capacitor is charged to an initial voltage of 3 kv and then disconnected from the charging source. An insulating material is placed between the plates, completely filling the space, resulting in a decrease in the capacitors voltage to 1 kv. Determine the original and new capacitance, the charge on the capacitor, and the dielectric constant of the material. 7

8 Take a parallel plate capacitor whose plates have an area of 2 m 2 and are separated by a distance of 1mm. The capacitor is charged to an initial voltage of 3 kv and then disconnected from the charging source. An insulating material is placed between the plates, completely filling the space, resulting in a decrease in the capacitors voltage to 1 kv. Determine the original and new capacitance, the charge on the capacitor, and the dielectric constant of the material. Given: V 1 =3,000 V V 2 =1,000 V A = 2.00 m 2 d = 0.01 m Find: C=? C 0 =? Q=? k=? Since we are dealing with the parallel-plate capacitor, the original capacitance can be found as 2 A m C0 = ε0 = ( C N m ) = 18 nf 3 d m The dielectric constant and the new capacitance are V C = κc = C = 318 nf = 54nF V2 The charge on the capacitor can be found to be ( )( ) 9 5 Q= C V = F V = C

9 How does an insulating dielectric material reduce electric fields by producing effective surface charge densities? Reorientation of polar molecules Induced polarization of non-polar molecules Dielectric Breakdown: breaking of molecular bonds/ionization of molecules. 9

10 17.1 Electric Current Whenever charges of like signs move in a given direction, a current is said to exist. Consider charges are moving perpendicularly to a surface of area A. Definition: the current is the rate at which charge flows through this surface. A I 10

11 17.1 Electric Current - Definition Given an amount of charge, Q, passing through the area A in a time interval t, the current is the ratio of the charge to the time interval. I = Q t A I 11

12 17.1 Electric Current - Units The SI units of current is the ampere (A). 1 A = 1 C/s 1 A of current is equivalent to 1 C of charge passing through the area in a time interval of 1 s. 12

13 17.1 Electric Current Remark 1 Currents may be carried by the motion of positive or negative charges. It is conventional to give the current the same direction as the flow of positive charge. 13

14 17.1 Electric Current Remark 2 In a metal conductor such as copper, the current is due to the motion of the electrons (negatively charged). The direction of the current in copper is thus opposite the direction of the electrons v I 14

15 17.1 Electric Current Remark 3 In a beam of protons at a particle accelerator (such as RHIC at Brookhaven national laboratory), the current is the same direction as the motion of the protons. In gases and electrolytes (e.g. Car batteries), the current is the flow of both positive and negative charges. 15

16 17.1 Electric Current Remark 4 It is common to refer to a moving charge as a mobile charge carrier. In a metal the charge carriers are electrons. In other conditions or materials, they may be positive or negative ions. 16

17 17.1 Electric Current Example Current in a light bulb The amount of charge that passes through the filament of a certain light bulb in 2.00 s is 1.67 c. Find. (A) the current in the light bulb. (B) the number of electrons that pass through the filament in 1 second. 17

18 The amount of charge that passes through the filament of a certain light bulb in 2.00 s is 1.67 c. Find. (A) the current in the light bulb. I Q 1.67C = = = t 2.00s 0.835A 18

19 The amount of charge that passes through the filament of a certain light bulb in 2.00 s is 1.67 c. Find. (b) the number of electrons that pass through the filament in 1 second. Reasoning: In 1 s, C of charge passes the cross-sectional sectional area of the filament. This total charge per second is equal to the number of electrons, N, times the charge on a single electron. 19

20 The amount of charge that passes through the filament of a certain light bulb in 2.00 s is 1.67 c. Find. (b) the number of electrons that pass through the filament in 1 second. Solution: ( 19 ) N = N C / electron = 0.835C q N N = 0.835C C/ electron = electrons 20

21 15.2 Current and Drift Speed Consider the current on a conductor of cross-sectional sectional area A. A q v d v d t 21

22 15.2 Current and Drift Speed (2) Volume of an element of length x is : V V = A x. Let n be the number of carriers per unit of volume. The total number of carriers in V V is: n A x. The charge in this volume is: Q Q = (n A x)q. Distance traveled at drift speed v d by carrier in time t: x = v d t. Hence: Q Q = (n A v d t)q. The current through the conductor: I = Q/ t t = n A v d q. 22

23 15.2 Current and Drift Speed (3) In an isolated conductor, charge carriers move randomly in all directions. When an external potential is applied across the conductor, it creates an electric field inside which produces a force on the electron. Electrons however still have quite a random path. As they travel through the material, electrons collide with other electrons, and nuclei, thereby losing or gaining energy. The work done by the field exceeds the loss by collisions. The electrons then tend to drift preferentially in one direction. 23

24 15.2 Current and Drift Speed - Example Question: A copper wire of cross-sectional sectional area 3.00x10-6 m 2 carries a current of 10. A. Assuming that each copper atom contributes one free electron to the metal, find the drift speed of the electron in this wire. The e density of copper is 8.95 g/cm 3. 24

25 Question: A copper wire of cross-sectional area 3.00x10-6 m 2 carries a current of 10 A. Assuming that each copper atom contributes one free electron to the metal, find the drift speed of the electron in this wire. The density of copper is 8.95 g/cm 3. Reasoning: We know: A = 3.00x10-6 m 2 I = 10 A. ρ = 8.95 g/cm 3. q = 1.6 x C. n = 6.02x10 23 atom/mol x 8.95 g/cm 3 x ( 63.5 g/mol) -1 n = 8.48 x electrons/ cm 3. 25

26 Question: A copper wire of cross-sectional area 3.00x10-6 m 2 carries a current of 10 A. Assuming that each copper atom contributes one free electron to the metal, find the drift speed of the electron in this wire. The density of copper is 8.95 g/cm 3. Ingredients: A = 3.00x10-6 m 2 ; I = 10 A.; ρ = 8.95 g/cm 3.; q = 1.6 x C. n = 8.48 x electrons/ cm 3. v d I 10.0 C/ s = = nqa electrons m C m = / ( 22 3 )( 19 )( ) m s 26

27 15.2 Current and Drift Speed - Comments Drift speeds are usually very small. Drift speed much smaller than the average speed between collisions. Electrons traveling at 2.46x10-6 m/s would would take 68 min to travel 1m. So why does light turn on so quickly when one flips a switch? The info travels at roughly 10 8 m/s 27

28 Mini-quiz Consider a wire has a long conical shape. How does the velocity of the electrons vary along the wire? Every portion of the wire carries the same current: as the cross sectional area decreases, the drift velocity must increase to carry the same value of current. This is dues to the electrical field lines being compressed into a smaller area, thereby increasing the strength of the electric field. 28

29 17.3 Resistance and Ohm s Law - Intro When a voltage (potential difference) is applied across the ends of a metallic conductor, the current is found to be proportional to the applied voltage. I V V I 29

30 17.3 Definition of Resistance In situations where the proportionality is exact, one can write. V = IR The proportionality constant R is called resistance of the conductor. The resistance is defined as the ratio. R = V I 30

31 17.3 Resistance - Units In SI, resistance is expressed in volts per ampere. A special name is given: ohms (Ω).( Example: if a potential difference of 10 V applied across a conductor produces a 0.2 A current, then one concludes the conductors has a resistance of 10 V/0.2 a = 50 Ω. 31

32 17.3 Ohm s Law Resistance in a conductor arises because of collisions between electrons and fixed charges within the material. In many materials, including most metals, the resistance is constant over a wide range of applied voltages. This is a statement of Ohm s law. Georg Simon Ohm ( ) 32

33 Linear or Ohmic Material I Non-Linear or Non-Ohmic Material I V V Most metals, ceramics Semiconductors e.g. diodes 33

34 Ohm s Law V = IR R understood to be independent of V. 34

35 Definition: Resistor: a conductor that provides a specified resistance in an electric circuit. The symbol for a resistor in circuit diagrams. 35

36 Example: Resistance of a Steam Iron All household electric devices are required to have a specified resistance (as well as many other characteristics ). Consider that the plate of a certain steam iron states the iron carries a current of 7.40 A when connected to a 120 V source. What is the resistance of the steam iron? V 120V R = = = 16.2Ω I 7.40A 36

### 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 4 Electrostatics and electrodynamics Capacitance and capacitors capacitors with dielectrics Electric current current and drift speed resistance and Ohm s law resistivity

### 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

### 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

### Capacitors (Chapter 26)

Capacitance, C Simple capacitive circuits Parallel circuits Series circuits Combinations Electric energy Dielectrics Capacitors (Chapter 26) Capacitors What are they? A capacitor is an electric device

### 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

### 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 2102 Gabriela González

Physics 2102 Gabriela González Any two charged conductors form a capacitor. Capacitance : C= Q/V Simple Capacitors: Parallel plates: C = ε 0 A/d Spherical : C = ε 0 4πab/(b-a) Cylindrical: C = ε 0 2πL/ln(b/a)

### Agenda for Today. Elements of Physics II. Capacitors Parallel-plate. Charging of capacitors

Capacitors Parallel-plate Physics 132: Lecture e 7 Elements of Physics II Charging of capacitors Agenda for Today Combinations of capacitors Energy stored in a capacitor Dielectrics in capacitors Physics

### 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

### 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

### Energy Stored in Capacitors

Energy Stored in Capacitors U = 1 2 qv q = CV U = 1 2 CV 2 q 2 or U = 1 2 C 37 Energy Density in Capacitors (1) We define the, u, as the electric potential energy per unit volume Taking the ideal case

### Physics 2401 Summer 2, 2008 Exam II

Physics 2401 Summer 2, 2008 Exam II e = 1.60x10-19 C, m(electron) = 9.11x10-31 kg, ε 0 = 8.845x10-12 C 2 /Nm 2, k e = 9.0x10 9 Nm 2 /C 2, m(proton) = 1.67x10-27 kg. n = nano = 10-9, µ = micro = 10-6, m

### 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

### Physics 1502: Lecture 8 Today s Agenda. Today s Topic :

Physics 1502: Lecture 8 Today s Agenda Announcements: Lectures posted on: www.phys.uconn.edu/~rcote/ HW assignments, solutions etc. Homework #3: On Masterphysics today: due next Friday Go to masteringphysics.com

### Physics 2212 GJ Quiz #3 Solutions Fall I. (16 points) The electric potential in a certain region of space depends on position according to

Physics 2212 GJ Quiz #3 Solutions Fall 2015 I. (16 points The electric potential in a certain region of space depends on position according to V (x, y, z = ( 2.0 V/m 2 ( x 2 + y 2 ( z + (3.0 V sin + 6.0

### 5. ELECTRIC CURRENTS

5. ELECTRIC CURRENTS TOPIC OUTLINE Section Recommended Time Giancoli Section 5.1 Potential Difference, Current, Resistance 5.2 Electric Circuits 3h 19.1, 19.2 6.2 Electric Field and Force 6.3 Magnetic

### Louisiana State University Physics 2102, Exam 2, March 5th, 2009.

PRINT Your Name: Instructor: Louisiana State University Physics 2102, Exam 2, March 5th, 2009. Please be sure to PRINT your name and class instructor above. The test consists of 4 questions (multiple choice),

### 9/22/16 ANNOUNCEMENT ANNOUNCEMENT FINAL EXAM

ANNOUNCEMENT Exam 1: Tuesday September 27, 2016, 8 PM 10 PM Location: Elliot Hall of Music Covers all readings, lectures, homework from Chapters 21 through 23 Multiple choice (1518 questions) Practice

### General Physics II (PHYS 104) Exam 2: March 21, 2002

General Physics II (PHYS 104) Exam 2: March 21, 2002 Name: Multiple Choice (3 points each): Answer the following multiple choice questions. Clearly circle the response (or responses) that provides the

### 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.

### 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,

### 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

### 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

### Dr. Todd Satogata (ODU/Jefferson Lab) Wednesday, February

University Physics 227N/232N Capacitors, Field Energy, Current and Ohm s Law Lab deferred to Fri Feb 28 QUIZ this Friday! (Feb 21) Fred lectures Monday! (Feb 24) Dr. Todd Satogata (ODU/Jefferson Lab) satogata@jlab.org

### 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

### Class 6. Capacitance and Capacitors. Physics 106. Winter Press CTRL-L to view as a slide show. Class 6. Physics 106.

and in and Energy Winter 2018 Press CTRL-L to view as a slide show. From last time: The field lines are related to the field as follows: What is the electric potential? How are the electric field and the

### 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

### 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

### Lecture 6. Previous Lecture. Capacitors C. Capacitors in series Capacitors in parallel E stored in an E field

Lecture 6 Previous Lecture Q Capacitors C V Capacitors in series Capacitors in parallel E stored in an E field 1 1 = = C C Δ series parallel This Lecture Current Resistivity as a property of materials

### 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

### Agenda for Today. Elements of Physics II. Capacitors Parallel-plate. Charging of capacitors

Capacitors Parallel-plate Physics 132: Lecture e 7 Elements of Physics II Charging of capacitors Agenda for Today Combinations of capacitors Energy stored in a capacitor Dielectrics in capacitors Physics

### What are the two types of current? The two types of current are direct current and alternating current.

Electric Current What are the two types of current? The two types of current are direct current and alternating current. Electric Current The continuous flow of electric charge is an electric current.

### What does it mean for an object to be charged? What are charges? What is an atom?

What does it mean for an object to be charged? What are charges? What is an atom? What are the components of an atom? Define the following: Electric Conductor Electric Insulator Define the following: Electric

### 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

### Objects usually are charged up through the transfer of electrons from one object to the other.

1 Part 1: Electric Force Review of Vectors Review your vectors! You should know how to convert from polar form to component form and vice versa add and subtract vectors multiply vectors by scalars Find

### ELECTRICITY & MAGNETISM NOTES

ELECTRICITY & MAGNETISM NOTES PHYSICS B4B BAKERSFIELD COLLEGE Rick Darke (Instructor) CHARGE Electric charge is a fundamental property associated with 2 of the 3 subatomic particles making up most matter.

### 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

### Monday 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

### PHYS 1444 Section 004 Lecture #10

PHYS 1444 Section 004 Lecture #10 Dr. Electric Current and Resistance The Battery Ohm s Law: Resisters Resistivity Electric Power Alternating Current Power Delivered by AC Today s homework is #6, due 10pm,

### 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

### News. Charge and Potential. Charge Density. Charge and Potential Quiz #2: Monday, 3/14, 10AM Same procedure as for quiz R +

News Charge and Potential Quiz #2: Monday, 3/14, 10AM Same procedure as for quiz 1 Review in class Fri, 3/11 Evening review, Fri, 3/11, 68PM 2 practice quizzes ( practice problems) Formula sheet R Charged

### 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

### ELECTRICITY. Chapter ELECTRIC CHARGE & FORCE

ELECTRICITY Chapter 17 17.1 ELECTRIC CHARGE & FORCE Essential Questions: What are the different kinds of electric charge? How do materials become charged when rubbed together? What force is responsible

### 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

### iclicker A metal ball of radius R has a charge q. Charge is changed q -> - 2q. How does it s capacitance changed?

1 iclicker A metal ball of radius R has a charge q. Charge is changed q -> - 2q. How does it s capacitance changed? q A: C->2 C0 B: C-> C0 C: C-> C0/2 D: C->- C0 E: C->-2 C0 2 iclicker A metal ball of

### Electric Charges & Current. Chapter 12. Types of electric charge

Electric Charges & Current Chapter 12 Types of electric charge Protons w/ + charge stuck in the nucleus Electrons w/ - charge freely moving around the nucleus in orbits 1 Conductors Allow the easy flow

### 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 24. Capacitance and Dielectrics Lecture 1. Dr. Armen Kocharian

Chapter 24 Capacitance and Dielectrics Lecture 1 Dr. Armen Kocharian Capacitors Capacitors are devices that store electric charge Examples of where capacitors are used include: radio receivers filters

### 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

### 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

### Chapter 2: Capacitor And Dielectrics

hapter 2: apacitor And Dielectrics In this chapter, we are going to discuss the different ways that a capacitor could be arranged in a circuit and how its capacitance could be increased. Overview apacitor

### PHYSICS - CLUTCH CH 24: CAPACITORS & DIELECTRICS.

!! www.clutchprep.com CONCEPT: CAPACITORS AND CAPACITANCE A CAPACITOR is formed by two surfaces of equal/opposite charge brought close together - Separation of charge potential energy stored Connecting

### Section 1: Electric Charge and Force

Electricity Section 1 Section 1: Electric Charge and Force Preview Key Ideas Bellringer Electric Charge Transfer of Electric Charge Induced Charges Charging by Contact Electric Force Electric Field Lines

### Chapter 2: Capacitors And Dielectrics

hapter 2: apacitors And Dielectrics 2.1 apacitance and capacitors in series and parallel L.O 2.1.1 Define capacitance and use capacitance apacitor is a device that is capable of storing electric charges

### 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

### Physics 1202: Lecture 4 Today s Agenda. Today s Topic :

Physics 1202: Lecture 4 Today s Agenda Announcements: Lectures posted on: www.phys.uconn.edu/~rcote/ HW assignments, solutions etc. Homework #1: On Masterphysics: due this coming Friday Go to the syllabus

### Chapter 25. Capacitance

Chapter 25 Capacitance 1 1. Capacitors A capacitor is a twoterminal device that stores electric energy. 2 2. Capacitance The figure shows the basic elements of any capacitor two isolated conductors of

### Electroscope Used to are transferred to the and Foil becomes and

Electricity Notes Chapter 17 Section 1: Electric Charge and Forces Electric charge is a variety of independent all with one single name. Electricity is related to, and both (-) and (+) carry a charge.

### 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

### Electric charges. Basics of Electricity

Electric charges Basics of Electricity Electron has a negative charge Neutron has a no charge Proton has a positive charge But what is a charge? Electric charge, like mass, is a fundamental property of

### Physics 202: Lecture 5, Pg 1

Resistance Resistors Series Parallel Ohm s law Electric Circuits Current Physics 132: Lecture e 15 Elements of Physics II Kirchhoff s laws Agenda for Today Physics 202: Lecture 5, Pg 1 Electric Current

### Electric Current. You must know the definition of current, and be able to use it in solving problems.

Today s agenda: Electric Current. You must know the definition of current, and be able to use it in solving problems. Current Density. You must understand the difference between current and current density,

### Name: Class: Date: Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

Name: Class: Date: AP REVIEW 4 Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. If a positively charged glass rod is used to charge a metal

### 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

### RADIO AMATEUR EXAM GENERAL CLASS

RAE-Lessons by 4S7VJ 1 CHAPTER- 2 RADIO AMATEUR EXAM GENERAL CLASS By 4S7VJ 2.1 Sine-wave If a magnet rotates near a coil, an alternating e.m.f. (a.c.) generates in the coil. This e.m.f. gradually increase

### CAPACITORS / ENERGY STORED BY CAPACITORS / CHARGING AND DISCHARGING

PHYSICS A2 UNIT 4 SECTION 3: CAPACITANCE CAPACITORS / ENERGY STORED BY CAPACITORS / CHARGING AND DISCHARGING # Question CAPACITORS 1 What is current? Current is the rate of flow of charge in a circuit

### 104 Practice Exam 1-2/21/02

104 Practice Exam 1-2/21/02 1. One mole of a substance contains 6.02 > 10 23 protons and an equal number of electrons. If the protons could somehow be separated from the electrons and placed in separate

### 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

### 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

### Current. source charges. test charg. 1. Charges in motion

Current 1. Charges in motion 1. Cause of motion 2. Where is it going? 3. Let's keep this going. 2. Current 1. Flow of particles in pipes. 2. A constant problem 3. Conservation Laws 4. Microscopic motion

### 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

### 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,

### Capacitance and Dielectrics. Chapter 26 HW: P: 10,18,21,29,33,48, 51,53,54,68

Capacitance and Dielectrics Chapter 26 HW: P: 10,18,21,29,33,48, 51,53,54,68 Capacitors Capacitors are devices that store electric charge and energy Examples of where capacitors are used include: radio

### 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

### 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

### 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

### Lecture 20. March 22/24 th, Capacitance (Part I) Chapter , Pages

Lecture 0 March /4 th, 005 Capacitance (Part I) Reading: Boylestad s Circuit Analysis, 3 rd Canadian Edition Chapter 10.1-6, Pages 8-94 Assignment: Assignment #10 Due: March 31 st, 005 Preamble: Capacitance

### Physics 2220 Fall 2010 George Williams SECOND MIDTERM - REVIEW PROBLEMS

Physics 0 Fall 010 George Williams SECOND MIDTERM - REVIEW PROBLEMS The last four problems are from last years second midterm. Solutions are available on the class web site.. There are no solutions for,

### Experiment FT1: Measurement of Dielectric Constant

Experiment FT1: Measurement of Dielectric Constant Name: ID: 1. Objective: (i) To measure the dielectric constant of paper and plastic film. (ii) To examine the energy storage capacity of a practical capacitor.

### Physics 2135 Exam 2 March 22, 2016

Exam Total Physics 2135 Exam 2 March 22, 2016 Key Printed Name: 200 / 200 N/A Rec. Sec. Letter: Five multiple choice questions, 8 points each. Choose the best or most nearly correct answer. B 1. An air-filled

### 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

### Chapter 18. Circuit Elements, Independent Voltage Sources, and Capacitors

Chapter 18 Circuit Elements, Independent Voltage Sources, and Capacitors Ideal Wire _ + Ideal Battery Ideal Resistor Ideal Capacitor Series Parallel An ideal battery provides a constant potential difference

### Electricity MR. BANKS 8 TH GRADE SCIENCE

Electricity MR. BANKS 8 TH GRADE SCIENCE Electric charges Atoms and molecules can have electrical charges. These are caused by electrons and protons. Electrons are negatively charged. Protons are positively

### Chapter 3: Current and Resistance. Direct Current Circuits

Chapter 3: Current and Resistance. Direct Current Circuits 3.1. Electric Current 3.2. Resistance and Resistivity 3.3. Ohm s Law and a Microscopic View of Ohm s Law 3.4. Semiconductors and Superconductors

### Physics 201. Professor P. Q. Hung. 311B, Physics Building. Physics 201 p. 1/3

Physics 201 p. 1/3 Physics 201 Professor P. Q. Hung 311B, Physics Building Physics 201 p. 2/3 Summary of last lecture Equipotential surfaces: Surfaces where the potential is the same everywhere, e.g. the

### Chapter 20. Capacitors, Resistors and Batteries

Chapter 20 Capacitors, Resistors and Batteries How is Discharging Possible?! E Positive and negative charges are attracted to each other: how can they leave the plates? Fringe field is not zero! Electrons

### 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

### Intermediate Physics PHYS102

Intermediate Physics PHYS102 Dr Richard H. Cyburt Assistant Professor of Physics My office: 402c in the Science Building My phone: (304) 384-6006 My email: rcyburt@concord.edu My webpage: www.concord.edu/rcyburt

### Physics 22: Homework 4

Physics 22: Homework 4 The following exercises encompass problems dealing with capacitor circuits, resistance, current, and resistor circuits. 1. As in Figure 1, consider three identical capacitors each

### 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

### PhysicsAndMathsTutor.com

Electricity May 02 1. The graphs show the variation with potential difference V of the current I for three circuit elements. PhysicsAndMathsTutor.com When the four lamps are connected as shown in diagram

### 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

### University Physics (PHY 2326)

Chapter 23 University Physics (PHY 2326) Lecture 5 Electrostatics Electrical energy potential difference and electric potential potential energy of charged conductors Capacitance and capacitors 3/26/2015

### Capacitor: any two conductors, one with charge +Q, other with charge -Q Potential DIFFERENCE between conductors = V

Physics 2102 Gabriela González Capacitor: any two conductors, one with charge +Q, other with charge -Q Potential DIFFERENCE between conductors = V Units of capacitance: Farad (F) = Coulomb/Volt -Q +Q Uses:

### fehmibardak.cbu.tr Temporary Office 348, Mühendislik Fakültesi B Blok

fehmibardak.cbu.tr Temporary Office 348, Mühendislik Fakültesi B Blok 1 Course Progress Introductory level Electrostatic, Coulomb s Law Electric Field, Gauss Law Magnetic field, Maxwell s Equations Current,

### Physics 115. Energy in E fields Electric Current Batteries Resistance. General Physics II. Session 21

Physics 115 General Physics II Session 21 Energy in E fields Electric Current Batteries Resistance R. J. Wilkes Email: phy115a@u.washington.edu Home page: http://courses.washington.edu/phy115a/ 5/6/14

### Chapter 16. Electric Energy and Capacitance

Chapter 16 Electric Energy and Capacitance Electric Potential Energy The electrostatic force is a conservative force It is possible to define an electrical potential energy function with this force Work