# General Physics (PHY 2140)

Size: px
Start display at page:

Transcription

1 General Physics (PHY 2140) Lecture 5 Electrostatics Electrical energy potential difference and electric potential potential energy of charged conductors Capacitance and capacitors Chapter 16 1

2 Lightning Review Last lecture: 1. Flux. Gauss s law. simplifies computation of electric fields Φ = EAcosθ = net Q ε o 2. Potential and potential energy V = VB VA = electrostatic force is conservative potential (a scalar) can be introduced as potential energy of electrostatic field per unit charge PE q Review Problem: Perhaps you have noticed sudden gushes of rain or hail moments after lightning strokes in thunderstorms. Is there any connection between the gush and the stroke or thunder? Or is this just a coincidence? V cloud E F = C mg qe 2

3 16.2 Electric potential and potential energy due to point charges Electric circuits: point of zero potential is defined by grounding some point in the circuit Electric potential due to a point charge at a point in space: point of zero potential is taken at an infinite distance from the charge With this choice, a potential can be found as V = q ke r Note: the potential depends only on charge of an object, q,, and a distance from this object to a point in space, r.. 3

4 Superposition principle for potentials If more than one point charge is present, their electric potential can be found by applying superposition principle The total electric potential at some point P due to several point charges is the algebraic sum of the electric potentials due to the individual charges. Remember that potentials are scalar quantities! 4

5 Potential energy of a system of point charges Consider a system of two particles If V 1 is the electric potential due to charge q 1 at a point P, then work required to bring the charge q 2 from infinity to P without acceleration is q 2 V 1. If a distance between P and q 1 is r, then by definition q 2 q 1 P r A PE = q V = k 2 1 e qq r 1 2 Potential energy is positive if charges are of the same sign and vice versa. 5

6 Mini-quiz: potential energy of an ion Three ions, Na +, Na +, and Cl -, located such, that they form corners of an equilateral triangle of side 2 nm in water. What is the electric potential energy of one of the Na + ions?? Cl - Na + Na + q q q q q PE = k + k = k q + q r r r [ ] Na Cl Na Na Na e e e Cl Na but : q = q! Cl Na qna PE = ke qna + qna = r [ ] 0 6

7 16.3 Potentials and charged conductors Recall that work is opposite of the change in potential energy, [ ] W = PE = q V V No work is required to move a charge between two points that are at the same potential. That is, W=0 if V B =V A Recall: 1. all charge of the charged conductor is located on its surface 2. electric field, E, is always perpendicular to its surface, i.e. no work is done if charges are moved along the surface Thus: potential is constant everywhere on the surface of a charged conductor in equilibrium B A but that s not all! 7

8 Because the electric field is zero inside the conductor, no work is required to move charges between any two points, i.e. [ ] 0 W = q V V = B If work is zero, any two points inside the conductor have the same potential, i.e. potential is constant everywhere inside a conductor Finally, since one of the points can be arbitrarily close to the surface of the conductor, the electric potential is constant everywhere inside a conductor and equal to its value at the surface! A Note that the potential inside a conductor is not necessarily zero, even though the interior electric field is always zero! 8

9 The electron volt A unit of energy commonly used in atomic, nuclear and particle physics is electron volt (ev( ev) The electron volt is defined as the energy that electron (or proton) gains when accelerating through a potential difference of 1 V Relation to SI: V ab =1 V 1 ev = C V V = J 9

10 Problem-solving strategy Remember that potential is a scalar quantity Superposition principle is an algebraic sum of potentials due to a system of charges Signs are important Just in mechanics, only changes in electric potential are significant, hence, the point you choose for zero electric potential is arbitrary. 10

11 Example : ionization energy of the electron in a hydrogen atom In the Bohr model of a hydrogen atom, the electron, if it is in the ground state, orbits the proton at a distance of r = m. Find the ionization energy of the atom, i.e. the energy required to remove the electron from the atom. Note that the Bohr model, the idea of electrons as tiny balls orbiting the nucleus, is not a very good model of the atom. A better picture is one in which the electron is spread out around the nucleus in a cloud of varying density; however, the Bohr model does give the right answer for the ionization energy 11

12 In the Bohr model of a hydrogen atom, the electron, if it is in the ground state, orbits the proton at a distance of r = 5.29 x m. Find the ionization energy, i.e. the energy required to remove the electron from the atom. Given: r = x m m e = kg m p = kg e = C Find: E=? The ionization energy equals to the total energy of the electron-proton system, E = PE + KE with e PE = ke, KE = m r v The velocity of e can be found by analyzing the force on the electron. This force is the Coulomb force; because the electron travels in a circular orbit, the acceleration will be the centripetal acceleration: ma = F or e c c m Thus, total energy is e v r e = k, e 2 or r 2 2 v 2 = e e 2 ke mr e, e m e kee e E = ke + = ke = r 2 mer 2r J ev 12

13 16.4 Equipotential surfaces They are defined as a surface in space on which the potential is the same for every point (surfaces of constant voltage) The electric field at every point of an equipotential surface is perpendicular to the surface convenient to represent by drawing equipotential lines 13

14 14

15 16.6 The definition of capacitance Capacitor: two conductors (separated by an insulator) usually oppositely charged a +Q b -Q The capacitance, C, of a capacitor is defined as a ratio of the magnitude of a charge on either conductor to the magnitude of the potential difference between the conductors Q C = V 15

16 1. A capacitor is basically two parallel conducting plates with insulating material in between. The capacitor doesn t have to look like metal plates. 2. When a capacitor is connected to an external potential, charges flow onto the plates and create a potential difference between the plates. 3. Capacitors in circuits symbols analysis follow from conservation of energy conservation of charge Capacitor for use in high-performance audio systems

17 Units of capacitance The unit of C is the farad (F), but most capacitors have values of C ranging from picofarads to microfarads (pf to µf). 1F = 1CV Recall, micro 10-6, nano 10-9, pico If the external potential is disconnected, charges remain on the plates, so capacitors are good for storing charge (and energy). 17

18 16.7 The parallel-plate plate capacitor The capacitance of a device depends on the geometric arrangement of the conductors C = ε 0 A d d +Q -Q A A where A is the area of one of the plates, d is the separation, ε 0 is a constant called the permittivity of free space, k e = 1 4πε 0 ε 0 = C 2 /N m2 18

19 Problem: parallel-plate plate capacitor A parallel plate capacitor has plates 2.00 m 2 in area, separated by a distance of 5.00 mm. A potential difference of 10,000 V is applied across the capacitor. Determine the capacitance the charge on each plate 19

20 A parallel plate capacitor has plates 2.00 m 2 in area, separated by a distance of 5.00 mm. A potential difference of 10,000 V is applied across the capacitor. Determine the capacitance the charge on each plate Solution: Given: V=10,000 V A = 2.00 m 2 d = 5.00 mm Find: C=? Q=? Since we are dealing with the parallel-plate capacitor, the capacitance can be found as A C = ε = C N m d 9 = F = 3.54 nf ( ) 2.00 m Once the capacitance is known, the charge can be found from the definition of a capacitance via charge and potential difference: ( )( ) 9 5 Q= C V = F 10000V = C 2 m 20

21 16.8 Combinations of capacitors It is very often that more than one capacitor is used in an electric circuit We would have to learn how to compute the equivalent capacitance of certain combinations of capacitors C 1 C 2 C 1 C 5 C 3 C 3 C 2 C 4 21

22 a. Parallel combination a Connecting a battery to the parallel combination of capacitors is equivalent to introducing the same potential difference for both capacitors, V=V ab b By definition, C 1 +Q 1 C 2 +Q 2 Q 1 Thus, C eq would be Q 2 Q = CV Q = C V C eq eq eq V1 = V2 = V A total charge transferred to the system from the battery is the sum of charges of the two capacitors, Q1+ Q2 = Q Q Q + Q Q Q Q Q = = + = + V V V V V V C = C + C Q + Q = Q 1 2 V = V = V

23 Parallel combination: notes Analogous formula is true for any number of capacitors, C = C + C + C + (parallel combination) eq It follows that the equivalent capacitance of a parallel combination of capacitors is greater than any of the individual capacitors 23

24 Problem: parallel combination of capacitors A 3 µf capacitor and a 6 µf capacitor are connected in parallel across an 18 V battery. Determine the equivalent capacitance and total charge deposited. 24

25 A 3 µf capacitor and a 6 µf capacitor are connected in parallel across an 18 V battery. Determine the equivalent capacitance and total charge deposited. a Given: C 1 +Q 1 C 2 +Q 2 V = 18 V C 1 = 3 µf C 2 = 6 µf V=V ab b Q 1 Q 2 Find: C eq =? Q=? First determine equivalent capacitance of C 1 and C 2 : C C C µ F 12 = = 9 Next, determine the charge ( )( ) 6 4 Q= C V = 9 10 F 18V = C 25

26 b. Series combination V=V ab b a By definition, C 1 C 2 Thus, C eq would be c +Q 1 Q 1 +Q 2 Q 2 Q = CV Q = CV Connecting a battery to the serial combination of capacitors is equivalent to introducing the same charge for both capacitors, Q1 = Q2 = Q A voltage induced in the system from the battery is the sum of potential differences across the individual capacitors, V = V1+ V2 1 V V1+ V2 V1 V2 V1 V2 = = + = + C Q Q Q Q Q Q eq = + + C C C C C C eq eq Q = Q = Q V + V = V

27 Series combination: notes Analogous formula is true for any number of capacitors, = (series combination) C C C C eq It follows that the equivalent capacitance of a series combination of capacitors is always less than any of the individual capacitance in the combination 27

28 Problem: series combination of capacitors A 3 µf capacitor and a 6 µf capacitor are connected in series across an 18 V battery. Determine the equivalent capacitance. 28

29 A 3 µf capacitor and a 6 µf capacitor are connected in series across an 18 V battery. Determine the equivalent capacitance and total charge deposited. a Given: V = 18 V C 1 = 3 µf C 2 = 6 µf V=V ab b C 1 C 2 c +Q 1 Q 1 +Q 2 Q 2 Find: C eq =? Q=? First determine equivalent capacitance of C 1 and C 2 : C eq CC C + C 1 2 = = 1 2 Next, determine the charge 2 µ F ( )( ) 6 5 Q= C V = 2 10 F 18V = C 29

### General Physics (PHY 2140)

General Physics (PHY 2140) Lecture 4 Electrostatics Electric flux and Gauss s law Electrical energy potential difference and electric potential potential energy of charged conductors http://www.physics.wayne.edu/~apetrov/phy2140/

### General Physics (PHY 2140)

General Physics (PHY 2140) Lecture 2 Electrostatics Electric flux and Gauss s law Electrical energy potential difference and electric potential potential energy of charged conductors http://www.physics.wayne.edu/~alan/

### Electric Potential Energy Chapter 16

Electric Potential Energy Chapter 16 Electric Energy and Capacitance Sections: 1, 2, 4, 6, 7, 8, 9 The electrostatic force is a conservative force It is possible to define an electrical potential energy

### Chapter 19 Electric Potential and Electric Field

Chapter 19 Electric Potential and Electric Field The electrostatic force is a conservative force. Therefore, it is possible to define an electrical potential energy function with this force. Work done

### Potential from a distribution of charges = 1

Lecture 7 Potential from a distribution of charges V = 1 4 0 X Smooth distribution i q i r i V = 1 4 0 X i q i r i = 1 4 0 Z r dv Calculating the electric potential from a group of point charges is usually

### 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

### Electric Potential. Capacitors (Chapters 28, 29)

Electric Potential. Capacitors (Chapters 28, 29) Electric potential energy, U Electric potential energy in a constant field Conservation of energy Electric potential, V Relation to the electric field strength

### Exam 1 Solutions. The ratio of forces is 1.0, as can be seen from Coulomb s law or Newton s third law.

Prof. Eugene Dunnam Prof. Paul Avery Feb. 6, 007 Exam 1 Solutions 1. A charge Q 1 and a charge Q = 1000Q 1 are located 5 cm apart. The ratio of the electrostatic force on Q 1 to that on Q is: (1) none

### Chapter 29. Electric Potential: Charged Conductor

hapter 29 Electric Potential: harged onductor 1 Electric Potential: harged onductor onsider two points (A and B) on the surface of the charged conductor E is always perpendicular to the displacement ds

### 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

### Physics 219 Question 1 January

Lecture 6-16 Physics 219 Question 1 January 30. 2012. A (non-ideal) battery of emf 1.5 V and internal resistance 5 Ω is connected to a light bulb of resistance 50 Ω. How much power is delivered to the

### Electric Potential Energy Conservative Force

Electric Potential Energy Conservative Force Conservative force or field is a force field in which the total mechanical energy of an isolated system is conserved. Examples, Gravitation, Electrostatic,

### Electrostatics so far

Electrostatics so far F = 1 2 1 2 2 Electric Force b/n q and q : qq 1 2 kq Electric Field E due to q : E = 1 1 r 2 kq q r q e = 1.6 x10-19 C k = 9 x 10 9 Nm 2 /C 2 Tesla Envy http://www.youtube.com/watch?v=jl

### Chapter 24: Capacitance and Dielectrics

Chapter 24: Capacitance and Dielectrics When you compress/stretch a spring, we are storing potential energy This is the mechanical method to store energy It is also possible to store electric energy as

### Chapter 16 Electrical Energy Capacitance. HW: 1, 2, 3, 5, 7, 12, 13, 17, 21, 25, 27 33, 35, 37a, 43, 45, 49, 51

Chapter 16 Electrical Energy Capacitance HW: 1, 2, 3, 5, 7, 12, 13, 17, 21, 25, 27 33, 35, 37a, 43, 45, 49, 51 Electrical Potential Reminder from physics 1: Work done by a conservative force, depends only

### COLLEGE PHYSICS Chapter 19 ELECTRIC POTENTIAL AND ELECTRIC FIELD

COLLEGE PHYSICS Chapter 19 ELECTRIC POTENTIAL AND ELECTRIC FIELD Electric Potential Energy and Electric Potential Difference It takes work to move a charge against an electric field. Just as with gravity,

### Electric Field of a uniformly Charged Thin Spherical Shell

Electric Field of a uniformly Charged Thin Spherical Shell The calculation of the field outside the shell is identical to that of a point charge. The electric field inside the shell is zero. What are the

### 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

### Physics (

Question 2.12: A charge of 8 mc is located at the origin. Calculate the work done in taking a small charge of 2 10 9 C from a point P (0, 0, 3 cm) to a point Q (0, 4 cm, 0), via a point R (0, 6 cm, 9 cm).

### Consider a point P on the line joining the two charges, as shown in the given figure.

Question 2.1: Two charges 5 10 8 C and 3 10 8 C are located 16 cm apart. At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero.

### PHY112 Chapter 16 Problems Electrical Energy and Capacitance

PHY112 Chapter 16 Problems Electrical Energy and Capacitance 1. A uniform electric field of magnitude 375 N/C pointing in the positive x-direction acts on an electron, which is initially at rest. After

### Chapter 24: Capacitance and Dielectrics

Chapter 24: Capacitance and Dielectrics When you compress/stretch a spring, we are storing potential energy This is the mechanical method to store energy It is also possible to store electric energy as

### 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

### Chapter 16. Electric Energy and Capacitance

Chapter 16 Electric Energy and Capacitance Electric Potential of a Point Charge The point of zero electric potential is taken to be at an infinite distance from the charge The potential created by a point

### Physics 2020: Sample Problems for Exam 1

Physics 00: Sample Problems for Eam 1 1. Two particles are held fied on the -ais. The first particle has a charge of Q 1 = 6.88 10 5 C and is located at 1 = 4.56 m on the -ais. The second particle has

### Today s agenda: Capacitors and Capacitance. You must be able to apply the equation C=Q/V.

Today s agenda: Capacitors and Capacitance. You must be able to apply the equation C=Q/V. Capacitors: parallel plate, cylindrical, spherical. You must be able to calculate the capacitance of capacitors

### W05D1 Conductors and Insulators Capacitance & Capacitors Energy Stored in Capacitors

W05D1 Conductors and Insulators Capacitance & Capacitors Energy Stored in Capacitors W05D1 Reading Assignment Course Notes: Sections 3.3, 4.5, 5.1-5.4 1 Outline Conductors and Insulators Conductors as

### Chapter 17 Lecture Notes

Chapter 17 Lecture Notes Physics 2424 - Strauss Formulas: qv = U E W = Fd(cosθ) W = - U E V = Ed V = kq/r. Q = CV C = κε 0 A/d κ = E 0 /E E = (1/2)CV 2 Definition of electric potential Definition of Work

### 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

### To receive full credit, you must show your work (including calculations and formulas used).

Page Score Problem : Problem 2: Problem 3: Problem 4: Problem 5: TOTAL: (25 pts) To receive full credit, you must show your work (including calculations and formulas used). If you do not wish your quiz

### EX. Potential for uniformly charged thin ring

EX. Potential for uniformly charged thin ring Q dq r R dφ 0 V ( Z ) =? z kdq Q Q V =, dq = Rdϕ = dϕ Q r 2πR 2π 2π k Q 0 = d ϕ 0 r 2π kq 0 2π = 0 d ϕ 2π r kq 0 = r kq 0 = 2 2 R + z EX. Potential for uniformly

### Electrical energy & Capacitance

Electrical energy & Capacitance PHY232 Remco Zegers zegers@nscl.msu.edu Room W109 cyclotron building http://www.nscl.msu.edu/~zegers/phy232.html work previously A force is conservative if the work done

### Physics 112 Homework 2 (solutions) (2004 Fall) Solutions to Homework Questions 2

Solutions to Homework Questions 2 Chapt16, Problem-1: A proton moves 2.00 cm parallel to a uniform electric field with E = 200 N/C. (a) How much work is done by the field on the proton? (b) What change

### Capacitors And Dielectrics

1 In this small e-book we ll learn about capacitors and dielectrics in short and then we ll have some questions discussed along with their solutions. I ll also give you a practices test series which you

### Capacitance and capacitors. Dr. Loai Afana

apacitance and capacitors apacitors apacitors are devices that store energy in an electric field. apacitors are used in many every-day applications Heart defibrillators amera flash units apacitors are

### Electrical energy & Capacitance

Electrical energy & Capacitance PHY232 Remco Zegers zegers@nscl.msu.edu Room W109 cyclotron building http://www.nscl.msu.edu/~zegers/phy232.html work previously A force is conservative if the work done

### 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

### Nicholas J. Giordano. Chapter 18. Electric Potential. Marilyn Akins, PhD Broome Community College

Nicholas J. Giordano www.cengage.com/physics/giordano Chapter 18 Electric Potential Marilyn Akins, PhD Broome Community College Electric Potential Electric forces can do work on a charged object Electrical

### Chapter 19 Electric Charges, Forces, and Fields

Chapter 19 Electric Charges, Forces, and Fields Outline 19-1 Electric Charge 19-2 Insulators and Conductors 19-3 Coulomb s Law 19-4 The Electric Field 19-5 Electric Field Lines 19-6 Shield and Charging

### 2014 F 2014 AI. 1. Why must electrostatic field at the surface of a charged conductor be normal to the surface at every point? Give reason.

2014 F 1. Why must electrostatic field at the surface of a charged conductor be normal to the surface at every point? Give reason. 2. Figure shows the field lines on a positive charge. Is the work done

### Physics Electricity & Op-cs Lecture 8 Chapter 24 sec Fall 2017 Semester Professor

Physics 24100 Electricity & Op-cs Lecture 8 Chapter 24 sec. 1-2 Fall 2017 Semester Professor Kol@ck How Much Energy? V 1 V 2 Consider two conductors with electric potentials V 1 and V 2 We can always pick

### Electric Potential (Chapter 25)

Electric Potential (Chapter 25) Electric potential energy, U Electric potential energy in a constant field Conservation of energy Electric potential, V Relation to the electric field strength The potential

### Question 20.1a Electric Potential Energy I

Question 20.1a Electric Potential Energy I A proton and an electron are in a constant electric field created by oppositely charged plates. You release the proton from the positive side and the electron

### LESSON 2 PHYSICS NOTES

LESSON 2 ELECTROSTATIC POTENTIAL AND CAPACITANCE SECTION I ELECTROSTATIC POTENTIAL ELECTRIC FIELD IS CONSERVATIVE In an electric field work done by the electric field in moving a unit positive charge from

### Chapter 24: Capacitance and Dielectrics. Capacitor: two conductors (separated by an insulator) usually oppositely charged. (defines capacitance)

hapter 4: apacitance and Dielectrics apacitor: two conductors (separated by an insulator) usually oppositely charged a b - ab proportional to charge / ab (defines capacitance) units: F / pc4: The parallel

### Chapter 24: Capacitance and Dielectrics

hapter 4: apacitance and Dielectrics apacitor: two conductors (separated by an insulator) usually oppositely charged a + b - ab proportional to charge = / ab (defines capacitance) units: F = / pc4: The

### Physics 202, Exam 1 Review

Physics 202, Exam 1 Review Logistics Topics: Electrostatics + Capacitors (Chapters 21-24) Point charges: electric force, field, potential energy, and potential Distributions: electric field, electric potential.

### Electric Potential. Chapter 23. PowerPoint Lectures for University Physics, Twelfth Edition Hugh D. Young and Roger A. Freedman

Chapter 23 Electric Potential PowerPoint Lectures for University Physics, Twelfth Edition Hugh D. Young and Roger A. Freedman Lectures by Reza Khanbabaie Goals for Chapter 23 Reminder about gravitational

### F 13. The two forces are shown if Q 2 and Q 3 are connected, their charges are equal. F 12 = F 13 only choice A is possible. Ans: Q2.

Q1. Three fixed point charges are arranged as shown in Figure 1, where initially Q 1 = 10 µc, Q = 15 µc, and Q 3 = 5 µc. If charges Q and Q 3 are connected by a very thin conducting wire and then disconnected,

### Physics 202, Exam 1 Review

Physics 202, Exam 1 Review Logistics Topics: Electrostatics (Chapters 21-24.6) Point charges: electric force, field, potential energy, and potential Distributions: electric field, electric potential. Interaction

### 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

### AP Physics Study Guide Chapter 17 Electric Potential and Energy Name. Circle the vector quantities below and underline the scalar quantities below

AP Physics Study Guide Chapter 17 Electric Potential and Energy Name Circle the vector quantities below and underline the scalar quantities below electric potential electric field electric potential energy

### PHYSICS. Electrostatics

Electrostatics Coulomb s Law: SYNOPSIS SI unit of electric intensity is NC -1 Dimensions The electric intensity due to isolated point charge, Electric dipole moment, P = q (2a), SI unit is C m Torque on

### Electric Potential Practice Problems

Electric Potential Practice Problems AP Physics Name Multiple Choice 1. A negative charge is placed on a conducting sphere. Which statement is true about the charge distribution (A) Concentrated at the

### Electrostatic Potential and Capacitance Examples from NCERT Text Book

Electrostatic Potential and Capacitance Examples from NCERT Text Book 1. (a) Calculate the potential at a point P due to a charge of 4 10 located 9 cm away. (b) Hence obtain the done in bringing a charge

### 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

### 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

### PHY102 Electricity Course Summary

TOPIC 1 ELECTOSTTICS PHY1 Electricity Course Summary Coulomb s Law The magnitude of the force between two point charges is directly proportional to the product of the charges and inversely proportional

### ELECTROSTATIC CBSE BOARD S IMPORTANT QUESTIONS OF 1 MARKS

ELECTROSTATIC CBSE BOARD S IMPORTANT QUESTIONS OF 1 MARKS 1. Name any two basic properties of electric charge. [1] 2. Define the term electric dipole-moment. [1] 3. Write the physical quantity, which has

### UNIT 102-2: ELECTRIC POTENTIAL AND CAPACITANCE Approximate time two 100-minute sessions

Name St.No. Date(YY/MM/DD) / / Section UNIT 1022: ELECTRIC POTENTIAL AND CAPACITANCE Approximate time two 100minute sessions I get a real charge out of capacitors. P. W. Laws OBJECTIVES 1. To understand

### Agenda for Today. Elements of Physics II. Conductors and Insulators Movement of charges Conservation of charge Static electricity Electroscope

Physics 132: Lecture e 5 Elements of Physics II Agenda for Today Conductors and Insulators Movement of charges Conservation of charge Static electricity Electroscope Physics 201: Lecture 1, Pg 1 Problem

### Physics (

Exercises Question 2: Two charges 5 0 8 C and 3 0 8 C are located 6 cm apart At what point(s) on the line joining the two charges is the electric potential zero? Take the potential at infinity to be zero

### A 12-V battery does 1200 J of work transferring charge. How much charge is transferred? A source of 1.0 µc is meters is from a positive test

1 A source of 1.0 µc is 0.030 meters is from a positive test charge of 2.0 µc. (a) What is the force on the test charge? (b) What is the potential energy of the test charge? (c) What is the strength of

### 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,

### PH 1120 Electricity and Magnetism Term B, 2009 STUDY GUIDE #2

PH 1120 Electricity and Magnetism Term B, 2009 STUDY GUIDE #2 In this part of the course we will study the following topics: Electric potential difference and electric potential for a uniform field Electric

### CHAPTER: 2 ELECTROSTATIC POTENTIAL AND CAPACITANCE

CHAPTER: 2 ELECTROSTATIC POTENTIAL AND CAPACITANCE. Define electric potential at a point. *Electric potential at a point is efine as the work one to bring a unit positive charge from infinity to that point.

### Potentials and Fields

Potentials and Fields Review: Definition of Potential Potential is defined as potential energy per unit charge. Since change in potential energy is work done, this means V E x dx and E x dv dx etc. The

### Chapter Electrostatic Potential and Capacitance

Chapter Electrostatic Potential and Capacitance C/ 2 C/2 Ans: Q6. MockTime.com Q1. A 4µF conductor is charged to 400 volts and then its plates are joined through a resistance of 1 kω. The heat produced

http://xkcd.com/567/ electrical energy & capacitance today & tomorrow first: wrap up Gauss law, then potential capacitors/dielectrics tomorrow rest of the week: circuits/current/resistance NEXT MON: exam

### Chapters 22/23: Potential/Capacitance Tuesday September 20 th

Chapters 22/23: Potential/Capacitance Tuesday September 20 th Mini Exam 2 on Thursday: Covers Chs. 21 and 22 (Gauss law and potential) Covers LONCAPA #3 to #6 (due this Wed.) No formula sheet allowed!!

### 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

### Danger High Voltage! Your friend starts to climb on this... You shout Get away! That s High Voltage!!! After you save his life, your friend asks:

Danger High Voltage! Your friend starts to climb on this... You shout Get away! That s High Voltage!!! After you save his life, your friend asks: What is Voltage anyway? Voltage... Is the energy (in Joules)

### What will the electric field be like inside the cavity?

What will the electric field be like inside the cavity? 1. There is no charge inside the gaussian surface so E = 0 2. There is no net flux through the surface but there is an E field 3. Gauss s law doesn

### Danger High Voltage! Your friend starts to climb on this... You shout Get away! That s High Voltage!!! After you save his life, your friend asks:

Danger High Voltage! Your friend starts to climb on this... You shout Get away! That s High Voltage!!! After you save his life, your friend asks: What is Voltage anyway? Voltage... Is the energy (U, in

### PHYSICS - Electrostatics

PHYSICS - Electrostatics Electrostatics, or electricity at rest, involves electric charges, the forces between them, and their behavior in materials. 22.1 Electrical Forces and Charges The fundamental

### Physics / Higher Physics 1A. Electricity and Magnetism Revision

Physics / Higher Physics 1A Electricity and Magnetism Revision Electric Charges Two kinds of electric charges Called positive and negative Like charges repel Unlike charges attract Coulomb s Law In vector

### Introduction)! Electrostatics is the study of stationary electric charges and fields (as opposed to moving charges and currents)

Higher'Physics'1B Electricity) Electrostatics)) Introduction) Electrostatics is the study of stationary electric charges and fields (as opposed to moving charges and currents) Properties)of)Electric)Charges)

### 7. A capacitor has been charged by a D C source. What are the magnitude of conduction and displacement current, when it is fully charged?

1. In which Orientation, a dipole placed in uniform electric field is in (a) stable (b) unstable equilibrium. 2. Two point charges having equal charges separated by 1 m in distance experience a force of

### CPS lesson Electric Field ANSWER KEY

CPS lesson Electric Field ANSWER KEY 1. A positively charged rod is brought near a conducting sphere on an insulated base. The opposite side of the sphere is briefly grounded. If the rod is now withdrawn,

### Electrostatics and Electric Potential - Outline

Electrostatics and Electric Potential - Outline 1. Understand the basic properties of electric charge, including conservation of charge and that charges are quantized. 2. Differentiate between conductors

### iclicker A device has a charge q=10 nc and a potential V=100V, what s its capacitance? A: 0.1 nf B: 1nF C: 10nF D: F E: 1F

Lecture 8 iclicker A device has a charge q=10 nc and a potential V=100V, what s its capacitance? A: 0.1 nf B: 1nF C: 10nF D: 10 10 F E: 1F iclicker A device has a charge q=10 nc and a potential V=100V,

### Chapter 12 Electrostatic Phenomena

Chapter 12 Electrostatic Phenomena 1. History Electric Charge The ancient Greeks noticed that if you rubbed amber (petrified tree resin) on fur, then the amber would have a property that it could attract

### Lecture 7. Capacitors and Electric Field Energy. Last lecture review: Electrostatic potential

Lecture 7. Capacitors and Electric Field Energy Last lecture review: Electrostatic potential V r = U r q Q Iclicker question The figure shows cross sections through two equipotential surfaces. In both

### Chapter 17 Electric Potential

Chapter 17 Electric Potential Units of Chapter 17 Electric Potential Energy and Potential Difference Relation between Electric Potential and Electric Field Equipotential Lines The Electron Volt, a Unit

### PHYS1212 Exam#2 Spring 2014

PHYS Exam# Spring 4 NAME There are 9 different pages in this quiz. Check now to see that you have all of them. CEDIT PAT A 6% PAT B 4% TOTAL % GADE All work and answers must be given in the spaces provided

### Chapter 25. Electric Potential

Chapter 25 Electric Potential Electric Potential Electromagnetism has been connected to the study of forces in previous chapters. In this chapter, electromagnetism will be linked to energy. By using an

### Chapter 19 Electric Potential and Electric Field Sunday, January 31, Key concepts:

Chapter 19 Electric Potential and Electric Field Sunday, January 31, 2010 10:37 PM Key concepts: electric potential electric potential energy the electron-volt (ev), a convenient unit of energy when dealing

### 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

### The Basic Capacitor. Water Tower / Capacitor Analogy. "Partnering With Our Clients for Combined Success"

CAPACITOR BASICS I How s Work The Basic A capacitor is an electrical device which serves to store up electrical energy for release at a predetermined time. In its most basic form, it is comprised of three

### PHYS 1441 Section 002 Lecture #7

PHYS 1441 Section 002 Lecture #7 Monday, Sept. 25, 2017 Chapter 22 One last Gauss Law Example Chapter 23 Electric Potential Electric Potential Energy Electric Potential due to Point Charges Shape of the

### Electronics Capacitors

Electronics Capacitors Wilfrid Laurier University October 9, 2015 Capacitor an electronic device which consists of two conductive plates separated by an insulator Capacitor an electronic device which consists

### Physics 126 Fall 2004 Practice Exam 1. Answer will be posted about Oct. 5.

Physics 126 Fall 2004 Practice Exam 1. Answer will be posted about Oct. 5. 1. Which one of the following statements best explains why tiny bits of paper are attracted to a charged rubber rod? A) Paper

### Chapter 17 & 18. Electric Field and Electric Potential

Chapter 17 & 18 Electric Field and Electric Potential Electric Field Maxwell developed an approach to discussing fields An electric field is said to exist in the region of space around a charged object

### Chapter 19 Electric Potential Energy and Electric Potential Sunday, January 31, Key concepts:

Chapter 19 Electric Potential Energy and Electric Potential Sunday, January 31, 2010 10:37 PM Key concepts: electric potential electric potential energy the electron-volt (ev), a convenient unit of energy

### Electric potential energy The concept of electric potential and potential difference Motion of charges in electric field

In this chapter, you will learn: Electric potential energy The concept of electric potential and potential difference Motion of charges in electric field 2.1 Electric potential energy When a charged particle

### Objects can be charged by rubbing

Electrostatics Objects can be charged by rubbing Charge comes in two types, positive and negative; like charges repel and opposite charges attract Electric charge is conserved the arithmetic sum of the

### Physics 213: General Physics Fall :30 AM Lecture

Physics 213: General Physics Fall 2004 9:30 AM Lecture Midterm I Solutions Tuesday, September 21, 2004 Chem-Phys 153 Name (print): Signature: Student Number: Your Seat Number (on back of chair): 1. Immediately

### Physics 2B Notes - Capacitors Spring 2018

Definition of a Capacitor Special Case: Parallel Plate Capacitor Capacitors in Series or Parallel Capacitor Network Definition of a Capacitor Webassign Chapter 0: 8, 9, 3, 4, 5 A capacitor is a device