# Current. I = ei e = en e Av d. The current, which is Coulomb s per second, is simply

Size: px
Start display at page:

Download "Current. I = ei e = en e Av d. The current, which is Coulomb s per second, is simply"

Transcription

1

2 Current The current, which is Coulomb s per second, is simply I = ei e = en e Av d e is the charge is the electron! ne is the density of electrons! A is the cross sectional area of the wire! vd is the drift velocity of the electrons area A Drift velocity

3 Current and E-Field Using the current from earlier, and the drift speed, the current is proportional to the electric field! which can be written as I = e2 n e m e AE I = AE = e2 n e where m e The material constant σ is called the conductivity (SI unit = Ω -1 m -1 ). The inverse quantity = 1 is called the resistivity (SI unit: Ω m).

4 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest magnitude of current, I? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info

5 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest magnitude of current, I? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info Current is conserved. Think of water flow.

6 Current Density The current divided by the cross sectional area gives us the current density, J = I A = E A microscopic quantity that is proportional to the electric field. Note: The current actually flows against the electric field.

7 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest current density J? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info

8 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest current density J? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info Current is conserved so all the electrons must flow faster in the narrower part. This also means that B has greatest electric field (question from PIAZZA)!

9 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest conductivity σ? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info

10 A copper cylinder is machined to have the following shape. The ends are connected to a battery so that a current flows through the copper. Which region has the greatest conductivity σ? a) A! b) B! c) C! d) All three are the same! e) Not sure/ not enough info Conductivity and resistivity are microscopic properties of the material.

11 Rank these tubes by how hard it would be to push stuff (say towels) through them at the same rate. A B C a) A harder than B harder than C! b) C harder than B harder than A! c) B harder than C harder than A! d) A harder than C harder than B! e) C harder than A harder than B

12 Rank these tubes by how hard it would be to push stuff (say towels) through them at the same rate. A B C a) A harder than B harder than C! b) C harder than B harder than A! c) B harder than C harder than A! d) A harder than C harder than B! e) C harder than A harder than B

13 Resistance and Resistivity I = AE V = Ed We can combine and (but we re going to rename d to L) to get I = A L V Ohm s Law! V = IR The resistance R of a real wire depends on the cross sectional area A and its length L:! R = L A A macroscopic property of the whole wire depending on the length and cross sectional area.

14 Resistance Higher voltage leads to a larger electric field and an increase in drift speed and and increase in current.! This leads to more collisions, more vibrations, and more energy loss (heat, light). Battery Resistor Circuit

15 Power Dissipated in a Resistor The drop in voltage across a resistor means that energy is being lost: U = q The rate of energy lost is the power: V Using Ohm s Law: P = du dt = dq dt V = I V P = I 2 R = V 2 R This is the power dissipated in a component with resistance R and current I flowing through it.

16 Circuit Analysis

17 Circuits Galore Problems 1 and 2

18 Kirchhoff s Loop law A foundation of circuit analysis. The loop law comes from path independence: U = I ~F ~ds = q I ~E ~ds =0 The change in energy around a closed path is zero. We then know that U = qv gives V loop =0 Which is the loop law.

19 Kirchhoff s Laws Kirchhoff s Laws are summarized as: V 1 + V 2 + V 3 + V 4 =0

20 The Loop Law in Action Find the current running through the circuit. 9 V

21 Which light bulb is brighter? a) A! b) B! c) both the same

22 Which light bulb is brighter? a) A! b) B! c) both the same

23 Which lightbulbs are brighter? a) the bulbs in the circuit on the left! b) the bulb in the circuit on the right! c) the left circuit has one bulb brighter and one bulb dimmer than the bulb in the right circuit.! d) they re all the same brightness

24 Which lightbulbs are brighter? a) the bulbs in the circuit on the left! b) the bulb in the circuit on the right! c) the left circuit has one bulb brighter and one bulb dimmer than the bulb in the right circuit.! d) they re all the same brightness

25 Circuits Galore Problems 3 and 4

26 The switch is open. What is the potential difference between point A and B? A B V a) 0 V! b) 3 V! c) 6 V! d) 9 V! e) 12 V!

27 The switch is open. What is the potential difference between point A and B? A B V a) 0 V! b) 3 V! c) 6 V! d) 9 V! e) 12 V!

28 Circuits Galore Problems 5, 6 and 7

29 We close the switch. What is the voltage across the capacitor once the circuit has run for a while? a) 0 V! b) 11.8 V! c) 40 V! d) 60 V! e) Unable to determine.!

30 We close the switch. What is the voltage across the capacitor once the circuit has run for a while? a) 0 V! b) 11.8 V! c) 40 V! d) 60 V! e) Unable to determine.!

31 RC Circuits

32 RC Circuits Charging and discharging a capacitor is governed by exponential laws. charging: discharging: V max V max V C = V max 1 e t/rc V C = V max e t/rc Circuit Construction Kit PhET

33 RC Circuits We can define a time constant to characterize the exponential decay = RC It s mathematically identical to the lifetime in radioactive decay.

34 This graph shows VC of a capacitor that is separately discharged through three difference resistors. Rank the value of the resistance from smallest to largest. a) R1 > R2 > R3! b) R3 > R2 > R1! c) R1 > R3 > R2! d) R2 > R3 > R1

35 This graph shows VC of a capacitor that is separately discharged through three difference resistors. Rank the value of the resistance from smallest to largest. a) R1 > R2 > R3! b) R3 > R2 > R1! c) R1 > R3 > R2! d) R2 > R3 > R1

### Clicker Session Currents, DC Circuits

Clicker Session Currents, DC Circuits Wires A wire of resistance R is stretched uniformly (keeping its volume constant) until it is twice its original length. What happens to the resistance? 1) it decreases

### 10/14/2018. Current. Current. QuickCheck 30.3

Current If QCurrent is the total amount of charge that has moved past a point in a wire, we define the current I in the wire to be the rate of charge flow: The SI unit for current is the coulomb per second,

### Chapter 25: Electric Current

Chapter 25: Electric Current Conductors and Charge Carriers Consider a conducting piece of metal: The valence electrons are weakly bound to the nuclei form a fluidlike sea of electrons that can move through

### Chapter 28. Direct Current Circuits

Chapter 28 Direct Current Circuits Circuit Analysis Simple electric circuits may contain batteries, resistors, and capacitors in various combinations. For some circuits, analysis may consist of combining

### Version 001 CIRCUITS holland (1290) 1

Version CIRCUITS holland (9) This print-out should have questions Multiple-choice questions may continue on the next column or page find all choices before answering AP M 99 MC points The power dissipated

### Current and Resistance

Current and Resistance 1 Define the current. Understand the microscopic description of current. Discuss the rat at which the power transfer to a device in an electric current. 2 2-1 Electric current 2-2

### Physics Tutorial - Currents and Circuits

Question 1: Ion Channels Physics Tutorial - Currents and Circuits The biochemistry that takes place inside cells depends on various elements that are dissolved in water as ions. The ions enter cells through

### physics 4/7/2016 Chapter 31 Lecture Chapter 31 Fundamentals of Circuits Chapter 31 Preview a strategic approach THIRD EDITION

Chapter 31 Lecture physics FOR SCIENTISTS AND ENGINEERS a strategic approach THIRD EDITION randall d. knight Chapter 31 Fundamentals of Circuits Chapter Goal: To understand the fundamental physical principles

### Agenda for Today. Elements of Physics II. Resistance Resistors Series Parallel Ohm s law Electric Circuits. Current Kirchoff s laws

Resistance Resistors Series Parallel Ohm s law Electric Circuits Physics 132: Lecture e 17 Elements of Physics II Current Kirchoff s laws Agenda for Today Physics 201: Lecture 1, Pg 1 Clicker Question

### ConcepTest PowerPoints

ConcepTest PowerPoints Chapter 19 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for

### Power lines. Why do birds sitting on a high-voltage power line survive?

Power lines At large distances, the resistance of power lines becomes significant. To transmit maximum power, is it better to transmit high V, low I or high I, low V? (a) high V, low I (b) low V, high

### Physics Investigation 10 Teacher Manual

Physics Investigation 10 Teacher Manual Observation When a light bulb is connected to a number of charged capacitors, it lights up for different periods of time. Problem What does the rate of discharging

### Chapter 24: Electric Current

Chapter 24: Electric Current Electric current Electric current is a net flow of electric charge. Quantitatively, current is the rate at which charge crosses a given area. I = dq dt dq = q(n AL)=q(n Av

### Parallel Resistors (32.6)

Parallel Resistors (32.6) Resistors connected at both ends are called parallel resistors The important thing to note is that: the two left ends of the resistors are at the same potential. Also, the two

### Parallel Resistors (32.6)

Parallel Resistors (32.6) Resistors connected at both ends are called parallel resistors Neil Alberding (SFU Physics) Physics 121: Optics, Electricity & Magnetism Spring 2010 1 / 1 Parallel Resistors (32.6)

### Lecture 12 Chapter 28 RC Circuits Course website:

Lecture 12 Chapter 28 RC Circuits Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Today we are going to discuss: Chapter 28: Section 28.9 RC circuits Steady current Time-varying

### Circuits. PHY2054: Chapter 18 1

Circuits PHY2054: Chapter 18 1 What You Already Know Microscopic nature of current Drift speed and current Ohm s law Resistivity Calculating resistance from resistivity Power in electric circuits PHY2054:

Physics 142 Steady Currents Page 1 Steady Currents If at first you don t succeed, try, try again. Then quit. No sense being a damn fool about it. W.C. Fields Electric current: the slow average drift of

### RC Circuits. Lecture 13. Chapter 31. Physics II. Course website:

Lecture 13 Chapter 31 Physics II RC Circuits Course website: http://faculty.uml.edu/andriy_danylov/teaching/physicsii Lecture Capture: http://echo360.uml.edu/danylov201415/physics2spring.html Steady current

### week 6 chapter 31 Current and Resistance

week 6 chapter 31 Current and Resistance Which is the correct way to light the lightbulb with the battery? 4) all are correct 5) none are correct 1) 2) 3) Which is the correct way to light the lightbulb

### ENERGY AND TIME CONSTANTS IN RC CIRCUITS By: Iwana Loveu Student No Lab Section: 0003 Date: February 8, 2004

ENERGY AND TIME CONSTANTS IN RC CIRCUITS By: Iwana Loveu Student No. 416 614 5543 Lab Section: 0003 Date: February 8, 2004 Abstract: Two charged conductors consisting of equal and opposite charges forms

### 1) Two lightbulbs, one rated 30 W at 120 V and another rated 40 W at 120 V, are arranged in two different circuits.

1) Two lightbulbs, one rated 30 W at 120 V and another rated 40 W at 120 V, are arranged in two different circuits. a. The two bulbs are first connected in parallel to a 120 V source. i. Determine the

### ConcepTest Clicker Questions. Chapter 26 Physics: for Scientists & Engineers with Modern Physics, 4th edition Giancoli

ConcepTest Clicker Questions Chapter 26 Physics: for Scientists & Engineers with Modern Physics, 4th edition Giancoli 2008 Pearson Education, Inc. This work is protected by United States copyright laws

### Chapter 3: Electric Current And Direct-Current Circuits

Chapter 3: Electric Current And Direct-Current Circuits 3.1 Electric Conduction 3.1.1 Describe the microscopic model of current Mechanism of Electric Conduction in Metals Before applying electric field

### Chapter 7 Direct-Current Circuits

Chapter 7 Direct-Current Circuits 7. Introduction... 7. Electromotive Force... 7.3 Resistors in Series and in Parallel... 4 7.4 Kirchhoff s Circuit Rules... 6 7.5 Voltage-Current Measurements... 8 7.6

### Laboratory 7: Charging and Discharging a Capacitor Prelab

Phys 132L Fall 2018 Laboratory 7: Charging and Discharging a Capacitor Prelab Consider a capacitor with capacitance C connected in series to a resistor with resistance R as shown in Fig. 1. Theory predicts

### Direct-Current Circuits

Direct-Current Circuits A'.3/.". 39 '- )232.-/ 32,+/" 7+3(5-.)232.-/ 7 3244)'03,.5B )*+,"- &'&./( 0-1*234 35-2567+- *7 2829*4-& )"< 35- )*+,"-= 9-4-- 3563 A0.5.C2/'-231).D')232.')2-1 < /633-">&@5-:836+-0"1464-625"-4*43"

### Chapter 26 & 27. Electric Current and Direct- Current Circuits

Chapter 26 & 27 Electric Current and Direct- Current Circuits Electric Current and Direct- Current Circuits Current and Motion of Charges Resistance and Ohm s Law Energy in Electric Circuits Combination

### Inductance, RL Circuits, LC Circuits, RLC Circuits

Inductance, R Circuits, C Circuits, RC Circuits Inductance What happens when we close the switch? The current flows What does the current look like as a function of time? Does it look like this? I t Inductance

### Chapter 19 Lecture Notes

Chapter 19 Lecture Notes Physics 2424 - Strauss Formulas: R S = R 1 + R 2 +... C P = C 1 + C 2 +... 1/R P = 1/R 1 + 1/R 2 +... 1/C S = 1/C 1 + 1/C 2 +... q = q 0 [1-e -t/(rc) ] q = q 0 e -t/(rc τ = RC

### 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),

### 52 VOLTAGE, CURRENT, RESISTANCE, AND POWER

52 VOLTAGE, CURRENT, RESISTANCE, AND POWER 1. What is voltage, and what are its units? 2. What are some other possible terms for voltage? 3. Batteries create a potential difference. The potential/voltage

### 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,

### Exam 3--PHYS 102--S14

Name: Exam 3--PHYS 102--S14 Multiple Choice Identify the choice that best completes the statement or answers the question. 1. Which of these statements is always true? a. resistors in parallel have the

### 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

### Chapter 19. Electric Current, Resistance, and DC Circuit Analysis

Chapter 19 Electric Current, Resistance, and DC Circuit Analysis I = dq/dt Current is charge per time SI Units: Coulombs/Second = Amps Direction of Electron Flow _ + Direction of Conventional Current:

### 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

### Chapter 26 Direct-Current Circuits

Chapter 26 Direct-Current Circuits 1 Resistors in Series and Parallel In this chapter we introduce the reduction of resistor networks into an equivalent resistor R eq. We also develop a method for analyzing

### Inductance, Inductors, RL Circuits & RC Circuits, LC, and RLC Circuits

Inductance, Inductors, RL Circuits & RC Circuits, LC, and RLC Circuits Self-inductance A time-varying current in a circuit produces an induced emf opposing the emf that initially set up the timevarying

### Sierzega: DC Circuits 4 Searching for Patterns in Series and Parallel Circuits

Searching for Series and Parallel Circuits. Observe and Design Draw circuit diagrams according to the word descriptions below. Build the circuits and use the symbols to represent the battery and the light

### Chapter 25 Current, Resistance, and Electromotive Force

Chapter 25 Current, Resistance, and Electromotive Force Lecture by Dr. Hebin Li Goals for Chapter 25 To understand current and how charges move in a conductor To understand resistivity and conductivity

### PRACTICE EXAM 2 for Midterm 2

PRACTICE EXAM 2 for Midterm 2 Multiple Choice Questions 1) In the circuit shown in the figure, all the lightbulbs are identical. Which of the following is the correct ranking of the brightness of the bulbs?

### 8. Electric Currents

8. Electric Currents S. G. Rajeev January 30, 2011 An electric current is produced by the movement of electric charges. In most cases these are electrons. A conductor is a material through which an electric

### Physics for Scientists & Engineers 2

Review The resistance R of a device is given by Physics for Scientists & Engineers 2 Spring Semester 2005 Lecture 8 R =! L A ρ is resistivity of the material from which the device is constructed L is the

### Lecture 39. PHYC 161 Fall 2016

Lecture 39 PHYC 161 Fall 016 Announcements DO THE ONLINE COURSE EVALUATIONS - response so far is < 8 % Magnetic field energy A resistor is a device in which energy is irrecoverably dissipated. By contrast,

### XII PHYSICS [CURRENT ELECTRICITY] CHAPTER NO. 13 LECTURER PHYSICS, AKHSS, K.

XII PHYSICS LECTURER PHYSICS, AKHSS, K affan_414@live.com https://promotephysics.wordpress.com [CURRENT ELECTRICITY] CHAPTER NO. 13 CURRENT Strength of current in a conductor is defined as, Number of coulombs

### Physics 169. Luis anchordoqui. Kitt Peak National Observatory. Wednesday, March 8, 17

Physics 169 Kitt Peak National Observatory Luis anchordoqui 1 5.1 Ohm s Law and Resistance ELECTRIC CURRENT is defined as flow of electric charge through a cross-sectional area Convention i = dq dt Unit

### 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

Surprising as it may seem, the power of a computer is achieved simply by the controlled flow of charges through tiny wires and circuit elements. Chapter Goal: To understand the fundamental physical principles

### Chapter 26 Direct-Current Circuits

Chapter 26 Direct-Current Circuits 1 Resistors in Series and Parallel In this chapter we introduce the reduction of resistor networks into an equivalent resistor R eq. We also develop a method for analyzing

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

Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Equations: 2 2 1 e r q q F = k 2 e o r Q k q F E = = I R V = A L R ρ = )] ( 1 [ o o T T + = α ρ ρ V I V t Q P = = R V R I P 2 2 ) ( = = C Q

### Electric Charge and Electric field

Electric Charge and Electric field ConcepTest 16.1a Electric Charge I Two charged balls are repelling each other as they hang from the ceiling. What can you say about their charges? 1) one is positive,

### 4 Electric circuits. Serial and parallel resistors V 3 V 2 V Serial connection of resistors:

4 lectric circuits PHY67 Spring 006 Serial and parallel resistors Serial connection of resistors: As the current I through each of serially connected resistors is the same, one can use Ohm s law and write...

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

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

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

Electric Current Chapter 17 Current and Resistance Sections: 1, 3, 4, 6, 7, 9 Whenever electric charges of like signs move, an electric current is said to exist The current is the rate at which the charge

### Circuits Capacitance of a parallel-plate capacitor : C = κ ε o A / d. (ρ = resistivity, L = length, A = cross-sectional area) Resistance : R = ρ L / A

k = 9.0 x 109 N m2 / C2 e = 1.60 x 10-19 C ε o = 8.85 x 10-12 C2 / N m2 Coulomb s law: F = k q Q / r2 (unlike charges attract, like charges repel) Electric field from a point charge : E = k q / r2 ( towards

### Electric Currents. Resistors (Chapters 27-28)

Electric Currents. Resistors (Chapters 27-28) Electric current I Resistance R and resistors Relation between current and resistance: Ohm s Law Resistivity ρ Energy dissipated by current. Electric power

### 1. How does a light bulb work?

AP Physics 1 Lesson 12.a Electric Current and Circuits Outcomes 1. Determine the resistance of a resistor given length, cross-sectional area and length. 2. Relate the movement of charge to differences

### 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

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

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

### Electricity & Optics

Physics 241 Electricity & Optics Lecture 12 Chapter 25 sec. 6, 26 sec. 1 Fall 217 Semester Professor Koltick Circuits With Capacitors C Q = C V V = Q C + V R C, Q Kirchhoff s Loop Rule: V I R V = V I R

### RC Circuits (32.9) Neil Alberding (SFU Physics) Physics 121: Optics, Electricity & Magnetism Spring / 1

(32.9) We have only been discussing DC circuits so far. However, using a capacitor we can create an RC circuit. In this example, a capacitor is charged but the switch is open, meaning no current flows.

### College Physics B - PHY2054C

Power College - PHY2054C and 09/15/2014 My Office Hours: Tuesday 10:00 AM - Noon 206 Keen Building PHY2054C Power First Mini-Exam this week on Wednesday!! Location: UPL 101, 10:10-11:00 AM Exam on chapters

### Class 8. Resistivity and Resistance Circuits. Physics 106. Winter Press CTRL-L to view as a slide show. Class 8. Physics 106.

and Circuits and Winter 2018 Press CTRL-L to view as a slide show. Last time we learned about Capacitance Problems Parallel-Plate Capacitors Capacitors in Circuits Current Ohm s Law and Today we will learn

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

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

### Review. Multiple Choice Identify the letter of the choice that best completes the statement or answers the question.

Review Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. When more devices are added to a series circuit, the total circuit resistance: a.

### Lesson 8 Electrical Properties of Materials. A. Definition: Current is defined as the rate at which charge flows through a surface:

Lesson 8 Electrical Properties of Materials I. Current I A. Definition: Current is defined as the rate at which charge flows through a surface: + + B. Direction: The direction of positive current flow

### PHY232 Spring 2008 Jon Pumplin (Original ppt courtesy of Remco Zegers) Direct current Circuits

PHY232 Spring 2008 Jon Pumplin http://www.pa.msu.edu/~pumplin/phy232 (Original ppt courtesy of Remco Zegers) Direct current Circuits So far, we have looked at systems with only one resistor PHY232 Spring

### Lab 10: DC RC circuits

Name: Lab 10: DC RC circuits Group Members: Date: TA s Name: Objectives: 1. To understand current and voltage characteristics of a DC RC circuit 2. To understand the effect of the RC time constant Apparatus:

### 2. In words, what is electrical current? 3. Try measuring the current at various points of the circuit using an ammeter.

PS 12b Lab 1a Fun with Circuits Lab 1a Learning Goal: familiarize students with the concepts of current, voltage, and their measurement. Warm Up: A.) Given a light bulb, a battery, and single copper wire,

### Capacitance. A different kind of capacitor: Work must be done to charge a capacitor. Capacitors in circuits. Capacitor connected to a battery

Capacitance The ratio C = Q/V is a conductor s self capacitance Units of capacitance: Coulomb/Volt = Farad A capacitor is made of two conductors with equal but opposite charge Capacitance depends on shape

### Direct-Current Circuits. Physics 231 Lecture 6-1

Direct-Current Circuits Physics 231 Lecture 6-1 esistors in Series and Parallel As with capacitors, resistors are often in series and parallel configurations in circuits Series Parallel The question then

### Physics 2112 Unit 11

Physics 2112 Unit 11 Today s oncept: ircuits Unit 11, Slide 1 Stuff you asked about.. what happens when one resistor is in parallel and one is in series with the capacitor Differential equations are tough

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

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

### Circuits Gustav Robert Kirchhoff 12 March October 1887

Welcome Back to Physics 1308 Circuits Gustav Robert Kirchhoff 12 March 1824 17 October 1887 Announcements Assignments for Thursday, October 18th: - Reading: Chapter 28.1-28.2, 28.4 - Watch Video: https://youtu.be/39vkt4cc5nu

Lights, sound systems, microwave ovens, and computers are all connected by wires to a battery or an electrical outlet. How and why does electric current flow through a wire? Chapter Goal: To learn how

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

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

### 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:

### Ch 28-DC Circuits! 1.) EMF & Terminal Voltage! 9.0 V 8.7 V 8.7 V. V =! " Ir. Terminal Open circuit internal! voltage voltage (emf) resistance" 2.

Ch 28-DC Circuits! 1.) EMF & Terminal Voltage! 9.0 V 8.7 V 8.7 V V =! " Ir Terminal Open circuit internal! voltage voltage (emf) resistance" 2.) Resistors in series! One of the bits of nastiness about

### Chapter 26 Current and Resistance

Chapter 26 Current and Resistance Electric Current Although an electric current is a stream of moving charges, not all moving charges constitute an electric current. If there is to be an electric current

### NORTHERN ILLINOIS UNIVERSITY PHYSICS DEPARTMENT. Physics 211 E&M and Quantum Physics Spring Lab #4: Electronic Circuits I

NORTHERN ILLINOIS UNIVERSITY PHYSICS DEPARTMENT Physics 211 E&M and Quantum Physics Spring 2018 Lab #4: Electronic Circuits I Lab Writeup Due: Mon/Wed/Thu/Fri, Feb. 12/14/15/16, 2018 Background The concepts

### Handout 10: Inductance. Self-Inductance and inductors

1 Handout 10: Inductance Self-Inductance and inductors In Fig. 1, electric current is present in an isolate circuit, setting up magnetic field that causes a magnetic flux through the circuit itself. This

### Chapter 27. Circuits

Chapter 27 Circuits 1 1. Pumping Chagres We need to establish a potential difference between the ends of a device to make charge carriers follow through the device. To generate a steady flow of charges,

### Name: Lab Partner: Section:

Chapter 6 Capacitors and RC Circuits Name: Lab Partner: Section: 6.1 Purpose The purpose of this experiment is to investigate the physics of capacitors in circuits. The charging and discharging of a capacitor

### LABORATORY 4 ELECTRIC CIRCUITS I. Objectives

LABORATORY 4 ELECTRIC CIRCUITS I Objectives to be able to discuss potential difference and current in a circuit in terms of electric field, work per unit charge and motion of charges to understand that

### University Physics (PHY 2326)

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

### Chapter 28. Direct Current Circuits

Chapter 28 Direct Current Circuits Electromotive Force An electromotive force device, or emf device, is a source of constant potential. The emf describes the work done per unit charge and has units of

### Physics 42 Exam 2 PRACTICE Name: Lab

Physics 42 Exam 2 PRACTICE Name: Lab 1 2 3 4 Conceptual Multiple Choice (2 points each) Circle the best answer. 1.Rank in order, from brightest to dimmest, the identical bulbs A to D. A. C = D > B > A

### Chapter 26 Examples : DC Circuits Key concepts:

Chapter 26 Examples : DC Circuits Key concepts: Internal resistance : battery consists of some idealized source of voltage (called the electromotive force, or EMF, which uses the symbol ξ) and an effective

### Turn in scantron You keep these question sheets

Exam 2 on OCT. 15. 2018 - Physics 106 R. Schad YOUR NAME ¼À Turn in scantron You keep these question sheets 1) This is to identify the exam version you have IMPORTANT Mark the A 2) This is to identify

### Physics 115. General Physics II. Session 24 Circuits Series and parallel R Meters Kirchoff s Rules

Physics 115 General Physics II Session 24 Circuits Series and parallel R Meters Kirchoff s Rules R. J. Wilkes Email: phy115a@u.washington.edu Home page: http://courses.washington.edu/phy115a/ 5/15/14 Phys

### Current Electricity. ScienceLinks 9, Unit 4 SciencePower 9, Unit 3

Current Electricity ScienceLinks 9, Unit 4 SciencePower 9, Unit 3 Current Electricity The flow of negative charges (electrons) through conductors Watch the BrainPOPs: Electricity Current Electricity Activity:

### Physics 102 Spring 2007: Final Exam Multiple-Choice Questions

Last Name: First Name: Physics 102 Spring 2007: Final Exam Multiple-Choice Questions 1. The circuit on the left in the figure below contains a battery of potential V and a variable resistor R V. The circuit

### Capacitors GOAL. EQUIPMENT. CapacitorDecay.cmbl 1. Building a Capacitor

PHYSICS EXPERIMENTS 133 Capacitor 1 Capacitors GOAL. To measure capacitance with a digital multimeter. To make a simple capacitor. To determine and/or apply the rules for finding the equivalent capacitance

### Lecture #3. Review: Power

Lecture #3 OUTLINE Power calculations Circuit elements Voltage and current sources Electrical resistance (Ohm s law) Kirchhoff s laws Reading Chapter 2 Lecture 3, Slide 1 Review: Power If an element is

### Chapter 27: Current and Resistance

Chapter 7: Current and esistance In this section of the course we will be studying the flow of electric charge, current, in a circuit. We have already seen electric current when we first discussed electric

### Chapter 27 Current and Resistance 27.1 Electric Current

Chapter 27 Current and esistance 27.1 Electric Current Electric current: dq dt, unit: ampere 1A = 1C s The rate at which charge flows through a surface. No longer have static equilibrium. E and Q can 0

### 2/25/2014. Circuits. Properties of a Current. Conservation of Current. Definition of a Current A. I A > I B > I C B. I B > I A C. I C D. I A E.

Circuits Topics: Current Conservation of current Batteries Resistance and resistivity Simple circuits 0.1 Electromotive Force and Current Conventional current is the hypothetical flow of positive charges