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

Size: px
Start display at page:

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

Transcription

1 and in and Energy Winter 2018 Press CTRL-L to view as a slide show.

2 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 potential related? How can we find the electric field and the electric potential? How are electric fields and electric potentials used in practical applications? The electric potential is the potential energy divided by the charge The electric potential is also called the voltage Applying fields to a CRT in and Energy

3 Today we will discuss: in series and parallel circuits in and Energy

4 in and Energy

5 A capacitor consists of two conductors, one with a charge +Q and one with a charge Q. Often the conductors are parallel plates. The voltage difference between the conductors is V. Out of tradition and laziness, we usually write the voltage difference as just V. in and Energy

6 C Q V Units: Farad (F) 1 F = 1 C / 1 V A farad is very large Often will see µf or pf in and Energy

7 Q = CV A big capacitor holds a large charge at a small voltage. in and Energy

8 in and Energy

9 First developed by Pieter van Musschenbroek in Leyden in 1746 in and Energy

10 Parallel-Plate Capacitor The capacitance of a device depends on the geometric arrangement of the conductors For a parallel-plate capacitor whose plates are separated by air: in and Energy

11 Parallel-Plate Capacitor The capacitance of a device depends on the geometric arrangement of the conductors For a parallel-plate capacitor whose plates are separated by air: C = ɛ 0 A d in and Energy

12 Parallel-Plate Capacitor The capacitor consists of two parallel plates Each have area A They are separated by a distance d The + charge on one plate holds the charge on the other plate in place. in and Energy

13 Parallel-Plate Capacitor If the plates are large, the capacitor can hold more charge. If the plates are closer together, the capacitor can hold more charge, because the + charge attracts the charge more strongly. in and Energy

14 Parallel Plate Capacitor Consists of two conducting plates, one positive and one negative Charge is pulled to the inside surface of either plate The field outside either plate is zero in and Energy

15 Parallel Plate Capacitor Consists of two conducting plates, one positive and one negative Charge is pulled to the inside surface of either plate The field outside either plate is zero in and Energy

16 Electric Field in a Parallel-Plate Capacitor in and Energy The electric field between the plates is quite uniform

17 Example 1: Derive the Parallel-Plate Capacitor Equations Consider a parallel-plate capacitor with plates of area A separated by distance d. The electric field in a capacitor is in and Energy E = σ ɛ 0

18 Example 1: Derive the Parallel-Plate Capacitor Equations The surface charge density is the total charge of a plate divided by its total area: σ = Q A in and Energy This gives: E = σ ɛ 0 = Q ɛ 0 A

19 Example 1: Derive the Parallel-Plate Capacitor Equations The electric field can be given in terms of the voltage: E = V x The sign gives the field direction, but we re only interested in magnitude, so we ignore it. We also write V as V, giving us: in and Energy E = V d So the voltage is V = Ed = Qd ɛ 0 A

20 Example 1: Derive the Parallel-Plate Capacitor Equations The capacitance can then be found: C = Q V = Qɛ 0A Qd in and Energy

21 Example 1: Derive the Parallel-Plate Capacitor Equations The capacitance can then be found: C = Q V = ɛ 0A d in and Energy C = ɛ 0A d

22 A Short Problem: You have two square plates 1.00 m on each side and you wish to make a 1.00 F capacitor. (That s a huge capacitace!) If there is air between the plates, what is the separation distance? in and Energy

23 A Short Problem: You have two square plates 1.00 m on each side and you wish to make a 1.00 F capacitor. (That s a huge capacitace!) If there is air between the plates, what is the separation distance? C = ɛ 0A d d = d ɛ 0A C = m in and Energy

24 A Short Problem: You have two square plates 1.00 m on each side and you wish to make a 1.00 F capacitor. (That s a huge capacitace!) If there is air between the plates, what is the separation distance? in and Energy C = ɛ 0A d d = d ɛ 0A C That s much smaller than one atom! = m

25 in in and Energy

26 in The simplest capacitor circuit is a capacitor connected to a battery with a switch to allow current to flow. in and Energy This is schematically represented as:

27 in When we close the switch, charge flows from the battery into capacitor. in and Energy As the capacitor charges, it pushes charges in the wire in opposition to the battery.

28 in When the voltage on the capacitor matches the voltage of the battery, current ceases to flow. in and Energy The charge on the capacitor is Q = CV where V is the voltage of the battery.

29 Series and Parallel The most common ways of connecting multiple circuit elements are in "series" and "parallel" in and Energy Two capacitors joined in series. Two capacitors joined in parallel.

30 in Parallel The total charge is equal to the sum of the charges on the capacitors Q total = Q 1 + Q 2 The voltage across each capacitor is the same and the same as the voltage of the battery in and Energy

31 Combining in Parallel The capacitors are equivalent to a single capacitor with a capacitance of C eq Q eq = Q 1 + Q 2 in and Energy C eq V = C 1 V + C 2 V C eq = C 1 + C 2

32 Combining in Parallel Adding capacitance in parallel is analogous to increasing the area of a capacitor. in and Energy

33 Combining in Parallel C eq = C 1 + C 2 + The equivalent capacitance of a parallel combination of capacitors is greater than any of the individual capacitors in and Energy

34 in Series Consider the two capacitors shown below. in and Energy

35 in Series Consider the two capacitors shown below. in and Energy As + charge enters on the left, it drives charge from the right plate of the left capacitor to the left plate of the right capacitor.

36 in Series Consider the two capacitors shown below. in and Energy The charge on each capacitor is the same.

37 in Series V eq = V 1 + V 2 Q C eq = Q C 1 + Q C 2 1 C eq = 1 C C 2 in and Energy An equivalent capacitor can be found that performs the same function as the series combination The potential differences add up to the battery voltage

38 in Series V eq = V 1 + V 2 Q C eq = Q C 1 + Q C 2 1 C eq = 1 C C 2 in and Energy An equivalent capacitor can be found that performs the same function as the series combination The potential differences add up to the battery voltage

39 in Series V eq = V 1 + V 2 Q C eq = Q C 1 + Q C 2 1 C eq = 1 C C 2 in and Energy An equivalent capacitor can be found that performs the same function as the series combination The potential differences add up to the battery voltage

40 in Series V eq = V 1 + V 2 Q C eq = Q C 1 + Q C 2 1 C eq = 1 C C 2 in and Energy An equivalent capacitor can be found that performs the same function as the series combination The potential differences add up to the battery voltage

41 in Series Adding capacitors in series is analogous to increasing the distance between capacitor plates. The equivalent capacitance of a series combination is always less than any individual capacitor in the combination in and Energy

42 Energy Stored in a Capacitor Energy stored is U = 1 2 CV 2 From the definition of capacitance, this can be rewritten in different forms: U = 1 2 CV 2 = Q2 2C = 1 2 QV in and Energy

43 in and Energy

44 with A dielectric is an insulating material placed between the plates of a capacitor increase capacitance C = κc 0 = κɛ 0 (A/d) where κ is the dielectric constant include rubber, plastic, or waxed paper in and Energy

45 Dielectric Strength For any given plate separation, there is a maximum electric field that can be produced in the dielectric before it breaks down and begins to conduct This maximum electric field is called the dielectric strength in and Energy

46 with in and Energy Adding a dielectric between charged capacitor plates reduces the voltage. Why?

47 An Atomic Description of Polarization occurs when there is a separation between the negative charge and the positive charge of the dielectric The dielectric becomes polarized because it is in an electric field of the plates in and Energy

48 Adding a Dielectric to a Capacitor with Fixed Charge The charge on the dielectric creates a field that opposes the field of the plates in and Energy

49 Adding a Dielectric to a Capacitor with Fixed Charge The charge on the dielectric creates a field that opposes the field of the plates This reduces the total electric field and the voltage The capacitance therefore increases in and Energy

50 and Current in and Energy

51 We are going to make a human model of circuits Traditionally, we think of positive charge as moving in a circuit. You will be the positive charge. A few of you will be a neutral wire. Hold your hands up and repel each other. Now be a positively-charged wire. Now be a negatively-charged wire. If you were charges on a real wire, where would you go? in and Energy

52 A Battery A batery pushes charges onto one end of a wire and pulls charges off the other end. A few of you will be a battery behind the stand. Now make a current flow around the stand. Where is the wire positive, neutral, negative? Where is the energy of positive charges highest along the wire? What kind of energy is it? Where is the voltage highest in the wire? How do you think electrons actually move in a wire? in and Energy

53 A Resistor A few of you will be a resistor. Charges collide with atoms in the resistor and change their direction of flow. Be a large resistor. Be a small resistor. How does resistance affect current.? What could we do to get more current? in and Energy

54 A Resistor, Part B A few more students will make the resistor longer. What happens to the current? Now make the resitor shorter and wider. What happens to the current? What can you say about the voltage on the wire? in and Energy

55 A Capacitor The battery is now disconnected. But don t go away. A few of you will make a capacitor in front of the stand. Remember that you are replled by positive charges on the other plate, but attracted to the "negative protons" in your own metal plate. Now we ll hook up the battery. What happens to the total charge? What happens to the charge on each plate? What happens to the current? What happens to the voltage? in and Energy

56 Parallel Disconnect the battery again. Now split the capacitor into two separate capacitors, side by side. You will also need some extra wire. These capacitors are in parallel. Reconnect the battery. What can you say about the voltages across the two capacitors? What can you say about the charges on the capacitors? What happens if one capacitor is bigger than the other? in and Energy

57 Series Disconnect the battery Now connect the capacitors in series, one after the other. Reconnect the battery. What happens to the charges between the two capacitors? What can you say about the charge on each capacitor? What can you say about the voltages on the two capacitors? in and Energy

### 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,

### 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

### 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

### 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

### 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

### (3.5.1) V E x, E, (3.5.2)

Lecture 3.5 Capacitors Today we shall continue our discussion of electrostatics and, in particular, the concept of electrostatic potential energy and electric potential. The main example which we have

### 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

### Capacitors and more. Lecture 9. Chapter 29. Physics II. Course website:

Lecture 9 Chapter 29 Physics II Capacitors and more Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Lecture Capture: http://echo360.uml.edu/danylov201415/physics2spring.html The

### Capacitors and more. Lecture 9. Chapter 29. Physics II. Course website:

Lecture 9 Chapter 29 Physics II Capacitors and more Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Lecture Capture: http://echo360.uml.edu/danylov201415/physics2spring.html The

### Capacitors II. Physics 2415 Lecture 9. Michael Fowler, UVa

Capacitors II Physics 2415 Lecture 9 Michael Fowler, UVa Today s Topics First, some review then Storing energy in a capacitor How energy is stored in the electric field Dielectrics: why they strengthen

### Definition of Capacitance

Definition of Capacitance The capacitance, C, of a capacitor is defined as the ratio of the magnitude of the charge on either conductor to the potential difference between the conductors Q C = ΔV The SI

### BROCK UNIVERSITY. Name: Student #: Page 1 of 8

Name: Student #: BROCK UNIVERSITY Page 1 of 8 Mid-term Test 2: March 2010 Number of pages: 8 Course: PHYS 1P22/1P92 Number of students: 125 Examination date: 19 March 2010 Number of hours: 2 Time of Examination:

### Hollow Conductors. A point charge +Q is placed at the center of the conductors. The induced charges are: 1. Q(I1) = Q(I2) = -Q; Q(O1) = Q(O2)= +Q

O2 I2 O1 I1 Hollow Conductors A point charge +Q is placed at the center of the conductors. The induced charges are: 1. Q(I1) = Q(I2) = -Q; Q(O1) = Q(O2)= +Q 2. Q(I1) = Q(I2) = +Q; Q(O1) = Q(O2)= -Q 3.

### 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

### Capacitance. A capacitor consists of two conductors that are close but not touching. A capacitor has the ability to store electric charge.

Capacitance A capacitor consists of two conductors that are close but not touching. A capacitor has the ability to store electric charge. a) Parallel-plate capacitor connected to battery. (b) is a circuit

### 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

### 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

### 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

### 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),

### 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

### 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

### 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

### 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

### [1] (b) Fig. 1.1 shows a circuit consisting of a resistor and a capacitor of capacitance 4.5 μf. Fig. 1.1

1 (a) Define capacitance..... [1] (b) Fig. 1.1 shows a circuit consisting of a resistor and a capacitor of capacitance 4.5 μf. S 1 S 2 6.3 V 4.5 μf Fig. 1.1 Switch S 1 is closed and switch S 2 is left

### 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

### BROCK UNIVERSITY. Physics 1P22/1P92. Mid-term Test 2: 19 March Solutions

BROCK UNIVERSITY Physics 1P22/1P92 Mid-term Test 2: 19 March 2010 Solutions 1. [6 marks] (See Page 746, CP # 24, and pages 15 16 of the posted Ch. 22 lecture notes from 4 March.) A 3.0 V potential difference

### Physics 102: Lecture 04 Capacitors (& batteries)

Physics 102: Lecture 04 Capacitors (& batteries) Physics 102: Lecture 4, Slide 1 I wish the checkpoints were given to us on material that we learned from the previous lecture, rather than on material from

### 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

### ENGR 2405 Chapter 6. Capacitors And Inductors

ENGR 2405 Chapter 6 Capacitors And Inductors Overview This chapter will introduce two new linear circuit elements: The capacitor The inductor Unlike resistors, these elements do not dissipate energy They

### 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

### 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

### Parallel Plate Capacitor, cont. Parallel Plate Capacitor, final. Capacitance Isolated Sphere. Capacitance Parallel Plates, cont.

Chapter 6 Capacitance and Dielectrics Capacitors! Capacitors are devices that store electric charge! Examples of where capacitors are used include:! radio receivers (tune frequency)! filters in power supplies!

### Chapter 26. Capacitance and Dielectrics

Chapter 26 Capacitance and Dielectrics Capacitors Capacitors are devices that store electric charge Examples of where capacitors are used include: radio receivers filters in power supplies energy-storing

### General Physics II. Conducting concentric spheres Two concentric spheres of radii R and r. The potential difference between the spheres is

apacitors and Dielectrics The ideas of energy storage in E-fields can be carried a step further by understanding the concept of "apacitance" onsider a sphere with a total charge, Q, and a radius, R From

### 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

### CAPACITANCE. Capacitor. Because of the effect of capacitance, an electrical circuit can store energy, even after being de-energized.

D ircuits APAITANE APAITANE Because of the effect of capacitance, an electrical circuit can store energy, even after being de-energized. EO 1.5 EO 1.6 EO 1.7 EO 1.8 EO 1.9 DESRIBE the construction of a

### I. Conductors and Insulators :

Chapter 6 : Conductors - Insulators - Capacitors We have, till now, studied the electric charges and the interactions between them but not evoked how the electricity can be transfered? which meterials

### 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

### Chapter 24 Capacitance and Dielectrics

Chapter 24 Capacitance and Dielectrics 1 Capacitors and Capacitance A capacitor is a device that stores electric potential energy and electric charge. The simplest construction of a capacitor is two parallel

### PH213 Chapter 24 Solutions

PH213 Chapter 24 Solutions 24.12. IDENTIFY and S ET UP: Use the expression for derived in Example 24.4. Then use Eq. (24.1) to calculate Q. E XECUTE: (a) From Example 24.4, The conductor at higher potential

### General Physics (PHY 2140)

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

### PHYS 212 Final Exam (Old Material) Solutions - Practice Test

PHYS 212 Final Exam (Old Material) Solutions - Practice Test 1E If the ball is attracted to the rod, it must be made of a conductive material, otherwise it would not have been influenced by the nearby

### Chapter 24 Capacitance and Dielectrics

Chapter 24 Capacitance and Dielectrics 1 Capacitors and Capacitance A capacitor is a device that stores electric potential energy and electric charge. The simplest construction of a capacitor is two parallel

### 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

### Chapter 24: Capacitance and dielectrics

Chapter 24: Capacitance and dielectrics Capacitor: a device store electric energy How to define capacitance In parallel and/or in series Electric energy stored in a capacitor Dielectric materials Capacitor:

### Chapter 8. Capacitors. Charging a capacitor

Chapter 8 Capacitors You can store energy as potential energy by pulling a bowstring, stretching a spring, compressing a gas, or lifting a book. You can also store energy as potential energy in an electric

### 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)

### 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

### Capacitance and Dielectrics

Slide 1 / 39 Capacitance and Dielectrics 2011 by Bryan Pflueger Capacitors Slide 2 / 39 A capacitor is any two conductors seperated by an insulator, such as air or another material. Each conductor has

### 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:

### 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

### Experiment 4. RC Circuits. Observe and qualitatively describe the charging and discharging (decay) of the voltage on a capacitor.

Experiment 4 RC Circuits 4.1 Objectives Observe and qualitatively describe the charging and discharging (decay) of the voltage on a capacitor. Graphically determine the time constant τ for the decay. 4.2

### ConcepTest PowerPoints

ConcepTest PowerPoints Chapter 16 Physics: Principles with Applications, 7 th edition Giancoli 2014 Pearson Education, Inc. This work is protected by United States copyright laws and is provided solely

### 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

### shown in Fig. 4, is initially uncharged. How much energy is stored in the two capacitors after the switch S is closed for long time?

Chapter 25 Term 083 Q13. Each of the two 25-µF capacitors, as shown in Fig. 3, is initially uncharged. How many Coulombs of charge pass through ammeter A after the switch S is closed for long time? A)

### PHYS 2135 Exam II March 20, 2018

Exam Total /200 PHYS 2135 Exam II March 20, 2018 Name: Recitation Section: Five multiple choice questions, 8 points each. Choose the best or most nearly correct answer. For questions 6-9, solutions must

### What is dynamic electricity?

Dynamic Electricity What is dynamic electricity? Has to do with charges in motion So we re talking about moving electrons Think about any electronic device Dynamic electricity Think back to properties

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

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

### Chapter 26. Capacitance and Dielectrics

Chapter 26 Capacitance and Dielectrics Capacitors Capacitors are devices that store electric charge Examples of where capacitors are used include: radio receivers filters in power supplies to eliminate

### 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 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

### Capacitors. Lecture 10. Chapter 26. My Capacitance is limited. PHYS.1440 Lecture 10 Danylov. Department of Physics and Applied Physics

Lecture 10 Chapter 26 Capacitors My Capacitance is limited Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss: Chapter 26: Section 26.2 The Geometry

### Physics 6B. Practice Final Solutions

Physics 6B Practice Final Solutions . Two speakers placed 4m apart produce sound waves with frequency 45Hz. A listener is standing m in front of the left speaker. Describe the sound that he hears. Assume

### Preview of Period 10: Electric Charge and Force

Preview of Period 10: Electric Charge and Force 10.1 Electric Charge and Forces What happens when you place a negatively charged rod near an object? How do charges cause objects to move? 10.2 Conductors,

### WELCOME TO PERIOD 14. Homework Exercise #13 is due today. Watch video 3 Edison s Miracle of Light for class discussion next Tuesday or Wednesday.

WELCOME TO PERIOD 14 Homework Exercise #13 is due today. Watch video 3 Edison s Miracle of Light for class discussion next Tuesday or Wednesday. PHYSICS 1103 PERIOD 14 What is an electric circuit? How

### 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

### 5: Capacitors July 8, 2008

5: Capacitors July 8, 2008 5.1 Definition A capacitor is a structure which has a certain capacity to hold an electric charge. It is essentially the simplest possible battery. The typical example of a capacitor,

### 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

### Physics 106 Sections 1 & 2 Midterm Exam #1 Fall 2011

Physics 106 Sections 1 & 2 Midterm Exam #1 Fall 2011 Instructor: Lawrence Rees 3-digit CID: This test has 25 problems. The CID is only used to return your test. If you forgot it, make one up. Do NOT write

### Chapter 24 Capacitance and Dielectrics

Chapter 24 Capacitance and Dielectrics Lecture by Dr. Hebin Li Goals for Chapter 24 To understand capacitors and calculate capacitance To analyze networks of capacitors To calculate the energy stored in

### 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

### Which one of the pipes emits sound with the lowest frequency? Which one of the pipes emits sound with the next lowest frequency?

The figures show standing waves of sound in six organ pipes of the same length. Each pipe has one end open and the other end closed. Warning: some of the figures show situations that are not possible.

### UNIT G485 Module Capacitors PRACTICE QUESTIONS (4)

UNIT G485 Module 2 5.2.1 Capacitors PRACTICE QUESTIONS (4) 1 A 2200 µf capacitor is charged to a p.d. of 9.0 V and then discharged through a 100 kω resistor. (a) Calculate : (i) The initial charge stored

### Chapter 26. Capacitance and Dielectrics

Chapter 26 Capacitance and Dielectrics Circuits and Circuit Elements Electric circuits are the basis for the vast majority of the devices used in society. Circuit elements can be connected with wires to

### c. They have electric charges that move freely d. Electrons are added to the rod a. charges are of unlike signs b. charges are of like signs

Physics Review Chapter 17 & 18 Name: Date: Period: 1. What sentence best characterizes electron conductors? a. They have low mass density b. They have high tensile strength c. They have electric charges

### Phys 2025, First Test. September 20, minutes Name:

Phys 05, First Test. September 0, 011 50 minutes Name: Show all work for maximum credit. Each problem is worth 10 points. Work 10 of the 11 problems. k = 9.0 x 10 9 N m / C ε 0 = 8.85 x 10-1 C / N m e

### On the axes of Fig. 4.1, carefully sketch a graph to show how the potential difference V across the capacitor varies with time t. Label this graph L.

1 (a) A charged capacitor is connected across the ends of a negative temperature coefficient (NTC) thermistor kept at a fixed temperature. The capacitor discharges through the thermistor. The potential

### Capacitors. HPP Activity 68v1. Charge Inside the Body A Close Look at Cell Membranes

HPP Activity 68v1 Capacitors Charge Inside the Body A Close Look at Cell Membranes Our bodies store and use charge to transmit signals across nerves and to tell certain cells what to do and when to do

### EXPERIMENT 5A RC Circuits

EXPERIMENT 5A Circuits Objectives 1) Observe and qualitatively describe the charging and discharging (decay) of the voltage on a capacitor. 2) Graphically determine the time constant for the decay, τ =.

### 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

### 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

### Physics 196 Final Test Point

Physics 196 Final Test - 120 Point Name You need to complete six 5-point problems and six 10-point problems. Cross off one 5-point problem and one 10-point problem. 1. Two small silver spheres, each with

### The next two questions pertain to the situation described below. Consider a parallel plate capacitor with separation d:

PHYS 102 Exams Exam 2 PRINT (A) The next two questions pertain to the situation described below. Consider a parallel plate capacitor with separation d: It is connected to a battery with constant emf V.

### Exam 1--PHYS 102--S16

Name: Exam 1--PHYS 102--S16 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. The up-quark, u, has an elementary charge of +(2/3)e and the down-quark, d,

### Tactics Box 23.1 Using Kirchhoff's Loop Law

PH203 Chapter 23 solutions Tactics Box 231 Using Kirchhoff's Loop Law Description: Knight/Jones/Field Tactics Box 231 Using Kirchhoff s loop law is illustrated Learning Goal: To practice Tactics Box 231

### AP Physics C. Electric Circuits III.C

AP Physics C Electric Circuits III.C III.C.1 Current, Resistance and Power The direction of conventional current Suppose the cross-sectional area of the conductor changes. If a conductor has no current,

### Chapter 26. Capacitance and Dielectrics

Chapter 26 Capacitance and Dielectrics Capacitors Capacitors are devices that store electric charge Examples of where capacitors are used include: radio receivers filters in power supplies to eliminate

### Physics 2135 Exam 2 October 20, 2015

Exam Total / 200 Physics 2135 Exam 2 October 20, 2015 Printed Name: Rec. Sec. Letter: Five multiple choice questions, 8 points each. Choose the best or most nearly correct answer. 1. A straight wire segment

### 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

### 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

### 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

### Sharpen thinking about connections among electric field, electric potential difference, potential energy

PHYS 2015 -- Week 6 Sharpen thinking about connections among electric field, electric potential difference, potential energy Apply the ideas to capacitance and the parallel plate capacitor For exclusive

### 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

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

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

### Physics Lecture: 16 MON 23 FEB Capacitance I

Physics 2113 Jonathan Dowling Physics 2113 Lecture: 16 MON 23 FEB Capacitance I Capacitors and Capacitance Capacitor: any two conductors, one with charge +Q, other with charge Q Potential DIFFERENCE between

### Capacitors. Example 1

Physics 30AP Resistors and apacitors I apacitors A capacitor is a device for storing electrical charge that consists of two conducting objects placed near one another but not touching. A A typical capacitor

### 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

### AP Physics C - E & M. Slide 1 / 39 Slide 2 / 39. Slide 4 / 39. Slide 3 / 39. Slide 6 / 39. Slide 5 / 39. Capacitance and Dielectrics.

Slide 1 / 39 Slide 2 / 39 P Physics & M apacitance and ielectrics 20151205 www.njctl.org Slide 3 / 39 apacitors capacitor is any two conductors seperated by an insulator, such as air or another material.