Chapter 2. Electric Fields Field Intensity Due to a Point Charge

Size: px
Start display at page:

Download "Chapter 2. Electric Fields Field Intensity Due to a Point Charge"

Transcription

1 Chapter 2 Electric Fields An electric field exists in a region if electrical forces are exerted on charged bodies in that region. The direction of an electric field at a point is the direction in which a small positive charge would move (under the influence of the field) if placed at that point. The electric field intensity or electric field strength (E) at a point is defined as the force exerted by the field on a unit charge placed at that point. (Unit = NC 1 = V m 1 ) It follows from the definition of electric field intensity that the force, F, exerted on a charge, Q, at a point where the field intensity is E is given by F = EQ (2.1) Field Intensity Due to a Point Charge Figure 2.1: Electric Field Strength/Intensity In Figure 2.1, the force, on the test charge, Q 0, due to the point charge, Q, in a medium of permittivity, ε, is given by 9

2 10 CHAPTER 2. ELECTRIC FIELDS F = k Q Q 0 r 2 (2.2) By definition, electric field intensity is force per unit charge and therefore the field intensity, E, at the site of Q 0 is given by In Equ. 2.3 only put the magnitude of the charge and NOT the sign. E = F/Q 0 Therefore, Electric Field Lines E = 1 4πε 0 Q r 2 (2.3) Electric field lines are imagined as lines pointing in the same direction as the electric field vector at any point. These are their properties: 1. The electric field vector E is always tangent to the electric field line at any point. 2. The area density of lines through a plane area perpendicular to the field lines is proportional to the strength of the field upon that area. Thus, E is large when the field lines are close together. When drawing electric field lines, follow these rules: 1. Lines begin at a positive charge and terminate at a negative charge, except when there is an excess of charge, in which case they terminate at infinity. 2. The number of lines drawn must be proportional to the magnitude of the charge. 3. No lines can cross. Note that these drawings are just visual representation; although the electric field is quantized in charge, it is not quantized in position.

3 11 Figure 2.2: Field Lines Figure 2.3: Electric field patterns

4 12 CHAPTER 2. ELECTRIC FIELDS In summary Our observations of electric fields caused by charges and their properties: There are two different kinds of charges, called positive and negative. Like charges attract; opposite charges repel each other. The force of attraction between two charges varies with the inverse square of their separation. Charge is conserved. Charge is quantized.

5 Chapter 3 Electric Potential Information about the electric field may be given by stating the field strength at any point; alternatively the potential can be quoted. (A) Work and energy Work is done when the point of application of a force (or a component of it) undergoes a displacement in its own direction. The product of the force (or its component) F and the displacement s is taken as a measure of the work done W, i.e. W = F s. When F is in newtons and s in metres, W is in newton-metres, or joules. If a body A exerts a force on body B and work is done, a transfer of energy occurs which is measured by the work done. So, if we raise a mass m through a vertical height h, the work done W by the force we apply (i.e. by mg) is W = mgh (assuming the earth s gravitational field strength g is constant). The energy transfer is mgh and we consider that the system gains and stores that amount of gravitational potential energy in its gravitational field. This energy is obtained from the transfer of chemical energy by our muscular activity. When the mass falls the system loses gravitational potential energy and, neglecting air resistance, there is a transfer of kinetic energy to the mass equal to the work done by gravity. 13

6 14 CHAPTER 3. ELECTRIC POTENTIAL (B) Meaning of potential A charge in an electric field experiences a force and if it moves, work will, in general, be done. If a positive charge is moved from A to B in a direction opposite to that of the field E, Figure 3.1a, an external agent has to do work against the forces of the field and energy has to be supplied. As a result, the system (of the charge in the field) gains an amount of electrical potential energy equal to the work done. This is analogous to a mass being raised in the earth s gravitational field g, Figure 3.1b. When the charge is allowed to return from B to A, work is done by the forces of the field and the electrical potential energy previously gained by the system is lost. If, for example, the motion is in a vacuum, an equivalent amount of kinetic energy is transferred to the charge. Figure 3.1: Analogy between electrical and gravitational potential energy. In general, the potential energy associated with a charge at a point in an electric field depends on the location of the point and the magnitude of the charge (since the force acting depends on the charge, i.e. F = QE). Therefore if we state the magnitude of the charge we can describe an electric field in terms of the potential energies of that charge at different points. A unit positive charge is chosen and the change in potential energy which occurs when a charge is moved from one point to another is called the change of potential of the field itself.

7 15 Hence the potential at point B in Figure 3.1 exceeds that at A by the energy needed to take unit positive charge from A to B. To be strictly accurate, however, we should refer to the energy needed per unit charge when a very small charge moves from one point to the other since the introduction of a unit charge would in general modify the field. If for theoretical purposes we select as the zero of potential the potential at an infinite distance from any electric charges, potential can be defined as follows. The potential at a point is a field is defined as the energy required to move unit positive charge from infinity to the point. It is always assumed that the charge does not affect the field. The choice of the zero of potential is purely arbitrary and although infinity may be a few hundred metres in some cases, in atomic physics where distances of m are involved it need only be a very small distance away from the charge responsible for the field. Potential is a property of a point in a field and is a scalar since it deals with a quantity of work done or potential energy per unit charge. The symbol for potential is V and the unit is the joule per coulomb (JC 1 ) or the volt (V ). Just as a mass moves from a point of higher gravitational potential to one of lower potential (i.e. it falls towards the earth s surface), so a positive charge is urged by an electric field to move from a point of higher electric potential to one of lower potential. Negative charges move in the opposite direction if free to do so. (C) Potential and field strength compared When describing a field, potential is usually a more useful quantity than field strength because, being a scalar, it can be added directly when more than one field is concerned. Field strength is a vector and addition (by the parallelogram law) is more complex. Also, it is often more important to know what energy changes occur (rather than what forces act) when charges move in a field and these are readily calculated if potentials are known.

8 16 CHAPTER 3. ELECTRIC POTENTIAL Potential due to a point charge The potential at a point A in the field of, and distance r from, an isolated point charge +Q situated at O in a medium of permittivity ε, Fig. 3.2, can be calculated. Imagine that a very small point charge +Q 0 is moved by an external agent from C, distance x from A, through a very small distance δx to B without affecting the field due to +Q. Figure 3.2: Assuming the repulsive force on +Q 0 due to the field remains constant over δx, the work done δw by the external agent over δx against the force of the field is δw = F ( δx) (3.1) (The minus sign is necessary because the displacement δ x is in the opposite direction to that in which F acts.) By Coulomb s law Therefore, F = 1 QQ 0 4πε x 2 (3.2) δw = 1 QQ 0 4πε x 2 ( δx) (3.3) The total work done W in bringing the charge from +Q 0 from infinity (where x = ) to

9 17 the point A, a distance r from O (where x = r). W = QQ 0 4πε r ( ) dx x 2 = QQ 0 4πε [ 1 x ] r (3.4) W = QQ 0 4πε 1 r (3.5) A. The potential V at A is the energy needed to move unit positive charge from infinity to V = W Q 0 (3.6) So, the potential V at a distance r from a point charge Q in a medium of permittivity ε is given by V = 1 4πε Q r (3.7) Note that Potential is a scalar quantity and therefore the potential at a point due to a number of point charges is the algebraic sum of the (seeparate) potentials due to each charge. The potential due to a positive charge is positive and that due to a negative charge is negative.

10 18 CHAPTER 3. ELECTRIC POTENTIAL Equipotentials Figure 3.3: Equipotential surfaces (in two dimensions) for (a) a point charge and (b) parallel plates All points in a field that have the same potential can be imagined as lying on a surface - called an equipotential surface. When a charge moves on such a surface no energy transfer occurs and no work is done. The force due to the field must therefore act at right angles to the equipotential surface at any point and so equipotential surfaces and field lines always intersect at right angles.

11 BISHOP ANSTEY HIGH SCHOOL & TRINITY COLLEGE EAST SIXTH FORM CXC CAPE PHYSICS, UNIT 2 Ms. S. S. CALBIO Homework #2 Due: Tuesday 8 th September 8:00am Electric Field Strength/ Intensity & Potential 1) Find (a) the potential, (b) the electric field intensity at a point C on a line ABC in a vacuum where AB=BC=5.0cm given that there are point charges of 6.0μC and -4.0 μc at A and B respectively. State the direction of the field. (Assume 1/4πε0= 9 x 10 9 mf -1 ) 2) ABC is an equilateral triangle of side 4.0cm in a vacuum. There are point charges of 8.0 μc at A and B. Find (a) the potential, (b) the electric field intensity at C. State the direction of the field. (Assume 1/4πε0= 9 x 10 9 mf -1 ) 3) a. For each of the following, state whether it is a scalar or a vector and give an appropriate unit: i. Electric potential ii. Electric field strength b. Points A and B are 0.10m apart. A point charge of +3.0 x 10-9 C is placed at A and a point charge of -1.0 x 10-9 C is placed at B. i. X is the point on the straight line through A and B, between A and B, where the electric potential is zero. Calculate the distance AX. ii. Show on a diagram the approximate position of a point, Y, on the straight line through A and B where the electric field strength is zero. Explain your reasoning, but no calculation is expected. S. S. Calbio

Electric Fields Part 1: Coulomb s Law

Electric Fields Part 1: Coulomb s Law Electric Fields Part 1: Coulomb s Law F F Last modified: 07/02/2018 Contents Links Electric Charge & Coulomb s Law Electric Charge Coulomb s Law Example 1: Coulomb s Law Electric Field Electric Field Vector

More information

Chapter 1 The Electric Force

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

More information

Chapter 17 & 18. Electric Field and Electric Potential

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

More information

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

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

More information

ELECTROSTATIC FIELDS

ELECTROSTATIC FIELDS ELECTROSTATIC FIELDS Electric charge Ordinary matter is made up of atoms which have positively charged nuclei and negatively charged electrons surrounding them. A body can become charged if it loses or

More information

Electric Potential Energy Chapter 16

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

More information

Objects can be charged by rubbing

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

More information

Electric Potential Energy & Electric Potential

Electric Potential Energy & Electric Potential Electric Potential Energy & Electric Potential Consider the following scenario. F E F E pt.a If we release the ve charge from pt.a The ELECTRIC FIELD produced by the ve charge pulls the ve charge to the

More information

Electrostatics Notes 2 Electric Field on a Single Charge

Electrostatics Notes 2 Electric Field on a Single Charge Electrostatics Notes 2 Electric Field on a Single Charge There are many similarities between gravitational and electrostatic forces. One such similarity is that both forces can be exerted on objects that

More information

Electrostatics. 3) positive object: lack of electrons negative object: excess of electrons. Particle Mass Electric Charge. m e = 9.

Electrostatics. 3) positive object: lack of electrons negative object: excess of electrons. Particle Mass Electric Charge. m e = 9. Electrostatics 1) electric charge: 2 types of electric charge: positive and negative 2) charging by friction: transfer of electrons from one object to another 3) positive object: lack of electrons negative

More information

Phys 102 Lecture 4 Electric potential energy & work

Phys 102 Lecture 4 Electric potential energy & work Phys 102 Lecture 4 Electric potential energy & work 1 Today we will... Learn about the electric potential energy Relate it to work Ex: charge in uniform electric field, point charges Apply these concepts

More information

Electric Charge and Electric Field AP Physics 4 Lecture Notes

Electric Charge and Electric Field AP Physics 4 Lecture Notes Electric Charge and Electric Field AP Physics 4 Lecture Notes Coulomb s Law The Electric Field Field Lines Electric Fields and Conductors Coulomb s law: Coulomb s Law Force (N) F F F k r F F F r Charge

More information

Handout 3: Electric potential and electric potential energy. Electric potential

Handout 3: Electric potential and electric potential energy. Electric potential Handout 3: Electric potential and electric potential energy Electric potential Consider a charge + fixed in space as in Figure. Electric potential V at any point in space is defined as the work done by

More information

Chapter 25. Electric Potential

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

More information

Electrostatics Notes 1 Charges and Coulomb s Law

Electrostatics Notes 1 Charges and Coulomb s Law Electrostatics Notes 1 Charges and Coulomb s Law Matter is made of particles which are or charged. The unit of charge is the ( ) Charges are, meaning that they cannot be It is thought that the total charge

More information

Electric Potential Energy & Electric Potential

Electric Potential Energy & Electric Potential Electric Potential Energy & Electric Potential Consider the following scenario. F E F E pt.a If we release the ve charge from pt.a The ELECTRIC FIELD produced by the ve charge pulls the ve charge to the

More information

What will the electric field be like inside the cavity?

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

More information

Semester 2 Physics (SF 026) Lecture: BP 3 by Yew Sze Fiona Website:

Semester 2 Physics (SF 026) Lecture: BP 3 by Yew Sze Fiona Website: Semester 2 Physics (SF 026) Lecture: BP 3 by Yew Sze Ling @ Fiona Website: http://yslphysics.weebly.com/ Chapter 1: Electrostatics The study of electric charges at rest, the forces between them and the

More information

PHYS ST semester Dr. Nadyah Alanazi. Lecture 11

PHYS ST semester Dr. Nadyah Alanazi. Lecture 11 1 PHYS 104 1 ST semester 1439-1440 Dr. Nadyah Alanazi Lecture 11 25.1 Potential Difference and Electric Potential When a test charge q 0 is placed in an electric field E created by some source charge,

More information

General Physics (PHY 2140)

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/

More information

Coulomb s Law. Phys102 Lecture 2. Key Points. Coulomb s Law The electric field (E is a vector!) References

Coulomb s Law. Phys102 Lecture 2. Key Points. Coulomb s Law The electric field (E is a vector!) References Phys102 Lecture 2 Phys102 Lecture 2-1 Coulomb s Law Key Points Coulomb s Law The electric field (E is a vector!) References SFU Ed: 21-5,6,7,8,9,10. 6 th Ed: 16-6,7,8,9,+. Phys102 Lecture 2 Phys102 Lecture

More information

Los Altos Physics Honors. Electrostatics: Electric Fields, Electric Forces, Electric Potentials and. Electric Potential Energy.

Los Altos Physics Honors. Electrostatics: Electric Fields, Electric Forces, Electric Potentials and. Electric Potential Energy. Los Altos Physics Honors Electrostatics: Electric Fields, Electric Forces, Electric Potentials and Electric Potential Energy Workbook adam.randall@mvla.net www.laphysics.com dls.mvla.net/los_altos Spring

More information

Recall Gravitational Potential Energy

Recall Gravitational Potential Energy Electric Potential Recall Gravitational Potential Energy How can you increase the gravitational potential energy of an object? Raise it above the surface of the earth. The amount of work done against earth

More information

Chapter 1. Electrostatics. The Electric Charge

Chapter 1. Electrostatics. The Electric Charge Chapter 1 Electrostatics The Electric Charge Electric charge, or electricity, can come from batteries and generators. But some materials become charged when they are rubbed. Their charge is sometimes called

More information

Introduction to Charges. BCLN PHYSICS 12 - Rev. Sept/2012

Introduction to Charges. BCLN PHYSICS 12 - Rev. Sept/2012 Electrostatics ~ Learning Guide Name: Instructions: Using a pencil, answer the following questions. The Pre-Reading is marked, based on effort, completeness, and neatness (not accuracy). The rest of the

More information

Practice Problem Solutions

Practice Problem Solutions Chapter 14 Fields and Forces Practice Problem Solutions Student Textbook page 638 1. Conceptualize the Problem - Force, charge and distance are related by Coulomb s law. The electrostatic force, F, between

More information

Chapter Assignment Solutions

Chapter Assignment Solutions Chapter 20-21 Assignment Solutions Table of Contents Page 558 #22, 24, 29, 31, 36, 37, 40, 43-48... 1 Lightning Worksheet (Transparency 20-4)... 4 Page 584 #42-46, 58-61, 66-69, 76-79, 84-86... 5 Chapter

More information

Chapter 23. Electric Fields

Chapter 23. Electric Fields Chapter 23 Electric Fields Electric Charges There are two kinds of electric charges Called positive and negative Negative charges are the type possessed by electrons Positive charges are the type possessed

More information

Physics 1202: Lecture 3 Today s Agenda

Physics 1202: Lecture 3 Today s Agenda Physics 1202: Lecture 3 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

More information

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

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)

More information

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

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

More information

Electric Potential Energy Conservative Force

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,

More information

Physics 1302, Exam 1 Review

Physics 1302, Exam 1 Review c V Andersen, 2006 1 Physics 1302, Exam 1 Review The following is a list of things you should definitely know for the exam, however, the list is not exhaustive. You are responsible for all the material

More information

Physics 12 ELECTROSTATICS

Physics 12 ELECTROSTATICS Physics 12 ELECTROSTATICS F = kq 1Q 2 r2 E = V d V = kq r E p = kq 1Q 2 r F = qe V = E p Q 1 000 000 Volts 1 000 000 Volts NAME: Block: Text References 3 rd Ed. Giancolli Pg. 416-30 4 th Ed. Giancolli

More information

47 CHARGE. 1. What are the basic particles of charge?

47 CHARGE. 1. What are the basic particles of charge? 47 CHARGE 1. What are the basic particles of charge? 2. There are three variables for charge listed to the right. Tell the typical circumstances when each is used. 3. Charge What are the units of charge?

More information

PHYSICS - CLUTCH CH 23: ELECTRIC POTENTIAL.

PHYSICS - CLUTCH CH 23: ELECTRIC POTENTIAL. !! www.clutchprep.com CONCEPT: ELECTRIC POTENTIAL ENERGY If you release 2 charges, they move gain. Where did it come from? - Two charges have a stored energy between them, called - ENERGY CONSERVATION:

More information

Chapter 17. Electric Potential Energy and the Electric Potential

Chapter 17. Electric Potential Energy and the Electric Potential Chapter 17 Electric Potential Energy and the Electric Potential Consider gravity near the surface of the Earth The gravitational field is uniform. This means it always points in the same direction with

More information

Algebra Based Physics Electric Field, Potential Energy and Voltage

Algebra Based Physics Electric Field, Potential Energy and Voltage 1 Algebra Based Physics Electric Field, Potential Energy and Voltage 2016 04 19 www.njctl.org 2 Electric Field, Potential Energy and Voltage Click on the topic to go to that section Electric Field *Electric

More information

charge of opposite signs attract / charges of the same sign repel

charge of opposite signs attract / charges of the same sign repel VISUAL PHYSICS ONLINE MODULE 4.1 ELECTRICITY ELECTRIC FIELD ELECTRIC POTENTIAL QUESTIONS and PROBLEMS (with ANSWRES) ex41b ex41c electric force F E [N] charge of opposite signs attract / charges of the

More information

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 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

More information

1.2 Energy of Charged Particles

1.2 Energy of Charged Particles 1.2 Energy of Charged Particles Objective 1: Recall Coulomb s Law which states that the electrostatic force between 2 charged particles is inversely proportional to the square of the distance between them.

More information

Lecture 2 [Chapter 21] Tuesday, Jan 17th

Lecture 2 [Chapter 21] Tuesday, Jan 17th Lecture 2 [Chapter 21] Tuesday, Jan 17th Administrative Items Assignments this week: read Ch 21 and Ch 22 in the textbook complete Pre-Lecture Ch22 HW assignment complete Ch 21 HW assignment [Pre-Lecture

More information

Chapter 11. Electricity. Electric Charge Atoms and Ions Coulomb s Law Electric Field Electric Field Lines Potential Difference

Chapter 11. Electricity. Electric Charge Atoms and Ions Coulomb s Law Electric Field Electric Field Lines Potential Difference Chapter 11 Electricity In This Chapter: Electric Charge Atoms and Ions Coulomb s Law Electric ield Electric ield Lines Potential Difference Electric Charge Electric charge, like mass, is one of the basic

More information

EL FORCE and EL FIELD HW-PRACTICE 2016

EL FORCE and EL FIELD HW-PRACTICE 2016 1 EL FORCE and EL FIELD HW-PRACTICE 2016 1.A difference between electrical forces and gravitational forces is that electrical forces include a. separation distance. b. repulsive interactions. c. the inverse

More information

Physics 1051 Lecture 14. Electric Potential. Physics General Physics II Oscillations, Waves and Magnetism

Physics 1051 Lecture 14. Electric Potential. Physics General Physics II Oscillations, Waves and Magnetism Physics 1051 Lecture 14 Electric Potential Lecture 14 - Contents 20.0 Describing Electric Phenomenon using Electric Potential 20.1 Electric Potential Difference and Electric Potential 20.2 Potential Difference

More information

MTE1 results. Mean 75% = 90/120

MTE1 results. Mean 75% = 90/120 MTE1 results Mean 75% = 90/120 Scores available at Learn@UW, your TAs have exams If your score is an F or a D, talk to us and your TAs for suggestions on how to improve From last times Electric charges

More information

Electric Field of a uniformly Charged Thin Spherical Shell

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

More information

General Physics (PHY 2140)

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/

More information

q C e C k (Equation 18.1) for the distance r, we obtain k (Equation 18.1), where Homework#1 3. REASONING

q C e C k (Equation 18.1) for the distance r, we obtain k (Equation 18.1), where Homework#1 3. REASONING Homework# 3. REASONING a. Since the objects are metallic and identical, the charges on each combine and produce a net charge that is shared equally by each object. Thus, each object ends up with one-fourth

More information

PHYS 221 General Physics II

PHYS 221 General Physics II PHYS 221 General Physics II Elec. Potential Energy, Voltage, Equipotentials Spring 2015 Assigned Reading: 18.1 18.3 Lecture 4 Review: Gauss Law Last Lecture E q enc o E EAcos Gauss Law Very useful to determine

More information

Chapter 25. Electric Potential

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

More information

Chapter 16. Electric Energy and Capacitance

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

More information

ELECTROSTATIC FORCE. ELECTROSTATICS - I Physics Without Fear.

ELECTROSTATIC FORCE. ELECTROSTATICS - I Physics Without Fear. ELECTROSTATIC FORCE ELECTROSTATICS - I Physics Without Fear CONTENTS Frictional Electricity Properties of Electric Charges Coulomb s Law Coulomb s Law in Vector Form Units of Charge Relative Permittivity

More information

Chapter 21 Electric Charge and Electric Field

Chapter 21 Electric Charge and Electric Field Chapter 21 Electric Charge and Electric Field 21-1 Static Electricity; Electric Charge and Its Conservation Objects can be charged by rubbing 21-1 Static Electricity; Electric Charge and Its Conservation

More information

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

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

More information

General Physics (PHY 2140)

General Physics (PHY 2140) General Physics (PHY 2140) Lecture 5 Electrostatics Electrical energy potential difference and electric potential potential energy of charged conductors Capacitance and capacitors http://www.physics.wayne.edu/~apetrov/phy2140/

More information

Electrostatics and Electric Potential - Outline

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

More information

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. 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

More information

CHAPTER 19 - ELECTRIC POTENTIAL ENERGY AND ELECTRIC POTENTIAL. Sections 1-5

CHAPTER 19 - ELECTRIC POTENTIAL ENERGY AND ELECTRIC POTENTIAL. Sections 1-5 CHAPTER 19 - ELECTRIC POTENTIAL ENERGY AND ELECTRIC POTENTIAL Sections 1-5 Objectives: After completing this unit, you should be able to: Understand an apply the concepts of electric potential energy,

More information

Electricity and Magnetism. Electric Potential Energy and Voltage

Electricity and Magnetism. Electric Potential Energy and Voltage Electricity and Magnetism Electric Potential Energy and Voltage Work and Potential Energy Recall from Mechanics that E mech = K + U is a conserved quantity for particles that interact via conservative

More information

Chapter 25. Electric Potential

Chapter 25. Electric Potential Chapter 25 Electric Potential Outline 25.1 Potential difference and electric Potential 25.2 Potential Difference and electric field 25.3 Electric Potential and Potential energy due to point charges 25.1

More information

Book page. Coulombs Law

Book page. Coulombs Law Book page Coulombs Law A Coulomb torsion balance A Coulomb torsion balance is used to measure the force between two charged objects Coulomb's Torsion Balance Two conducting spheres fixed on insulating

More information

PHYSICS - CLUTCH CALC-BASED PHYSICS 1E CH 23: ELECTRIC POTENTIAL.

PHYSICS - CLUTCH CALC-BASED PHYSICS 1E CH 23: ELECTRIC POTENTIAL. !! www.clutchprep.com CONCEPT: ELECTRIC POTENTIAL ENERGY If you release 2 charges, they move gain. Where did it come from? - Two charges have a stored energy between them, called - ENERGY CONSERVATION:

More information

PHYSICS - Electrostatics

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

More information

free space (vacuum) permittivity [ F/m]

free space (vacuum) permittivity [ F/m] Electrostatic Fields Electrostatic fields are static (time-invariant) electric fields produced by static (stationary) charge distributions. The mathematical definition of the electrostatic field is derived

More information

CHAPTER 1: ELECTROSTATICS

CHAPTER 1: ELECTROSTATICS CHAPTER 1: ELECTROSTATICS PSPM II 2005/2006 NO. 2 2. A 2 μc charge lies on the straight line between a 3 μc charge and a 1 μc charge. The separation between the 3 μc and 1 μc is 4 cm. (a) Draw the position

More information

CHAPTER 15 PRE-TEST: ELECTRIC FORCE AND FIELDS

CHAPTER 15 PRE-TEST: ELECTRIC FORCE AND FIELDS Class: Date: CHAPTER 5 PRE-TEST: ELECTRIC FORCE AND FIELDS Multiple Choice Identify the choice that best completes the statement or answers the question.. What happens when a rubber rod is rubbed with

More information

You should be able to demonstrate and show your understanding of:

You should be able to demonstrate and show your understanding of: OCR B Physics H557 Module 6: Field and Particle Physics You should be able to demonstrate and show your understanding of: 6.1: Fields (Charge and Field) Field: A potential gradient Field Strength: Indicates

More information

Electrostatics. 4πε 2) + Q / 2 4) 4 Q

Electrostatics. 4πε 2) + Q / 2 4) 4 Q Two spheres A and B of radius a and b respectively are at the same potential The ratio of the surface charge density of A to B is: ) a / b ) b / a a / b b / a Two free protons are separated by a distance

More information

7 ELECTRIC POTENTIAL

7 ELECTRIC POTENTIAL Chapter 7 Electric Potential 285 7 ELECTRIC POTENTIAL Figure 7.1 The energy released in a lightning strike is an excellent illustration of the vast quantities of energy that may be stored and released

More information

ELECTROSTATIC CBSE BOARD S IMPORTANT QUESTIONS OF 1 MARKS

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

More information

Chapter 23. Electric Fields Properties of Electric Charges Coulomb s Law The Electric Field Electric Field Lines

Chapter 23. Electric Fields Properties of Electric Charges Coulomb s Law The Electric Field Electric Field Lines Chapter 23 Electric Fields 23.1 Properties of Electric Charges 23.3 Coulomb s Law 23.4 The Electric Field 23.6 Electric Field Lines 1 23.1 Properties of Electric Charges Experiments 1-After running a comb

More information

Chapter 24. Electric Potential

Chapter 24. Electric Potential Chapter 24 Chapter 24 Electric Potential Electric Potential Energy When an electrostatic force acts between two or more charged particles within a system of particles, we can assign an electric potential

More information

Electrostatics Notes 1 Charges and Coulomb s Law

Electrostatics Notes 1 Charges and Coulomb s Law Electrostatics Notes 1 Charges and Coulomb s Law Ancient Greeks discovered that if amber (fossilized sap) is rubbed it will attract small objects. This is similar to when you run a comb through your hair

More information

Electric Potential Energy

Electric Potential Energy Electric Potential Energy the electric potential energy of two charges depends on the distance between the charges when two like charges are an infinite distance apart, the potential energy is zero An

More information

E&M: Worksheet 6 Fields, Potential, and Energy

E&M: Worksheet 6 Fields, Potential, and Energy Name Date Pd () (-) E&M: Worksheet 6 Fields, Potential, and Energy 1. Below are two parallel conducting plates, each carrying an equal quantity of excess charge of opposite type. The plates are separated

More information

Chapter 16. Properties of Electric Charge. Electric Charge. The Milikan Experiment. Properties of Electric Charge, continued

Chapter 16. Properties of Electric Charge. Electric Charge. The Milikan Experiment. Properties of Electric Charge, continued Properties of Electric Charge Electric Charge There are two kinds of electric charge. like charges repel unlike charges attract Electric charge is conserved. Positively charged particles are called protons.

More information

Review. Spring Semester /21/14. Physics for Scientists & Engineers 2 1

Review. Spring Semester /21/14. Physics for Scientists & Engineers 2 1 Review Spring Semester 2014 Physics for Scientists & Engineers 2 1 Notes! Homework set 13 extended to Tuesday, 4/22! Remember to fill out SIRS form: https://sirsonline.msu.edu Physics for Scientists &

More information

Electric Fields Electric charges exert forces on each other when they are a distance apart. The word Electric field is used to explain this action at

Electric Fields Electric charges exert forces on each other when they are a distance apart. The word Electric field is used to explain this action at Electricity & Magnetism Electric Fields Marline Kurishingal Electric Fields Electric charges exert forces on each other when they are a distance apart. The word Electric field is used to explain this action

More information

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 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

More information

Chapter 19 Electric Potential and Electric Field

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

More information

Downloaded from

Downloaded from Question 1.1: What is the force between two small charged spheres having charges of 2 10 7 C and 3 10 7 C placed 30 cm apart in air? Repulsive force of magnitude 6 10 3 N Charge on the first sphere, q

More information

Summary of electrostatics

Summary of electrostatics Summary of electrostatics 1 In electrostatics we deal with the electric effects of charges at rest. Electric charge can be defined as is the intrinsic characteristic that is associated with fundamental

More information

Exam 1--PHYS 102--S14

Exam 1--PHYS 102--S14 Class: Date: Exam 1--PHYS 102--S14 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. The magnitude of the charge on an electron is approximately: a. 10-23

More information

Physics 212 Exam I Sample Question Bank 2008 Multiple Choice: choose the best answer "none of the above" may can be a valid answer

Physics 212 Exam I Sample Question Bank 2008 Multiple Choice: choose the best answer none of the above may can be a valid answer Multiple Choice: choose the best answer "none of the above" may can be a valid answer The (attempted) demonstration in class with the pith balls and a variety of materials indicated that () there are two

More information

Chapter Electric Forces and Electric Fields. Prof. Armen Kocharian

Chapter Electric Forces and Electric Fields. Prof. Armen Kocharian Chapter 25-26 Electric Forces and Electric Fields Prof. Armen Kocharian First Observations Greeks Observed electric and magnetic phenomena as early as 700 BC Found that amber, when rubbed, became electrified

More information

Electric Fields and Potentials

Electric Fields and Potentials Electric Fields and Potentials INTRODUCTION Physicists use the concept of a field to explain the interaction of particles or bodies through space, i.e., the action-at-a-distance force between two bodies

More information

PHYSICS 1/23/2019. Chapter 25 Lecture. Chapter 25 The Electric Potential. Chapter 25 Preview

PHYSICS 1/23/2019. Chapter 25 Lecture. Chapter 25 The Electric Potential. Chapter 25 Preview PHYSICS FOR SCIENTISTS AND ENGINEERS A STRATEGIC APPROACH 4/E Chapter 25 Lecture RANDALL D. KNIGHT Chapter 25 The Electric Potential IN THIS CHAPTER, you will learn to use the electric potential and electric

More information

Chapter 18 Electric Force and Electric Fields. Sections

Chapter 18 Electric Force and Electric Fields. Sections Chapter 18 Electric Force and Electric Fields Sections 18.1 18.6 Objectives: After finishing this unit, you should be able to: Explain and demonstrate the First law of electrostatics and discuss charging

More information

Electrostatics so far

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

More information

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 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

More information

Matthew W. Milligan. Electric Fields. a figment reality of our imagination

Matthew W. Milligan. Electric Fields. a figment reality of our imagination Matthew W. Milligan Electric Fields a figment reality of our imagination Electrostatics I. Charge and Force - concepts and definition - Coulomb s Law II. Field and Potential - electric field strength &

More information

0J2 - Mechanics Lecture Notes 2

0J2 - Mechanics Lecture Notes 2 0J2 - Mechanics Lecture Notes 2 Work, Power, Energy Work If a force is applied to a body, which then moves, we say the force does work. In 1D, if the force is constant with magnitude F, and the body moves

More information

Electrostatics. Electrical properties generated by static charges. Introduction

Electrostatics. Electrical properties generated by static charges. Introduction Electrostatics Electrical properties generated by static charges Introduction First Greek discovery Found that amber, when rubbed, became electrified and attracted pieces of straw or feathers Introduction

More information

Electric Potential Energy and Voltage. Electric Potential Energy and Voltage Electric Potential Energy. Electric Potential Energy.

Electric Potential Energy and Voltage. Electric Potential Energy and Voltage Electric Potential Energy. Electric Potential Energy. Slide 1 / 105 Slide 2 / 105 How to Use this File Each topic is composed of brief direct instruction Electric Potential Energy and oltage There are formative assessment questions after every topic denoted

More information

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

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

More information

Electric Potential Energy and Voltage

Electric Potential Energy and Voltage Slide 1 / 105 Electric Potential Energy and Voltage www.njctl.org Slide 2 / 105 How to Use this File Each topic is composed of brief direct instruction There are formative assessment questions after every

More information

20.3 Coulomb's Law 20.4 The Concept of the Electric Field.notebook March 05, 2018

20.3 Coulomb's Law 20.4 The Concept of the Electric Field.notebook March 05, 2018 Section 20.3 Coulomb s Law Text: p. 642 Coulomb s Law Coulomb s law describes the force between two charged particles. Coulomb s Law Coulomb s law looks much like Newton s gravity except the charge q can

More information

Chapters 21 and 22: Giancoli, 4 th Edition Electrostatics

Chapters 21 and 22: Giancoli, 4 th Edition Electrostatics Chapters 21 and 22: Giancoli, 4 th Edition Electrostatics Electric Charges Coulomb s Law and Electric force The Electric Field Electric Field Lines Electric flux Gauss Law and applications of Gauss Law

More information

Chapter 19 Electric Charges, Forces, and Fields

Chapter 19 Electric Charges, Forces, and Fields Chapter 19 Electric Charges, Forces, and Fields 1 Overview of Chapter 19 Electric Charge! Insulators and Conductors! Coulomb s Law! The Electric Field! Electric Field Lines! Shielding and Charging by Induction

More information