# Chapter 13 Electric Circuits

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 Chapter 13 Electric Circuits

2 What is Electric Current? How does it resemble the flow of water in a pipe?

3 Can you get a flashlight bulb to light, with a battery and a single wire?

4 Electric Circuits and Electric Current! A flashlight, an electric toaster, and a car s starting motor all involve electric circuits and electric current. "For the flashlight bulb to light, there must be a closed or complete path from the bulb to both ends of the battery. "Such a path is called a circuit.

5 Electric Circuits and Electric Current! A flashlight, an electric toaster, and a car s starting motor all involve electric circuits and electric current. "In this circuit, the battery is the energy source, using energy from chemical reactions to separate positive and negative charges. "This leads to a voltage difference, with an excess of positive charges at one end of the battery and an excess of negative charges at the other. "These charges will tend to flow from one terminal to the other if we provide an external conducting path (the circuit).

6 ! A flow of electric charge is an electric current: where I is electric current, q is charge, I = q t and t is time.! The standard unit for electric current is the ampere: 1 A = 1 C / s "For example, if 3 C of charge flow through a wire in 2 s, then the electric current I is 3 C / 2 s = 1.5 A. "Positive charges moving to the right have the same effect as negative charges moving to the left.

7 ! A flow of electric charge is an electric current: where I is electric current, q is charge, I = q t and t is time.! The standard unit for electric current is the ampere: 1 A = 1 C / s "The direction of current is defined as the direction that positive charges would flow. "In reality, the charge carriers in a metal wire are negatively charged electrons.

8 ! In addition to an energy source and a conducting path, a circuit also includes some resistance to the current. "In the flashlight bulb, a very thin wire filament restricts the current because of its very small crosssectional area. "The wire filament gets hot as charges are forced through this constriction. "Its high temperature makes it glow, and we have light.

9 Two arrangements of a battery, bulb, and wire are shown below. Which of the two arrangements will light the bulb? a) Arrangement (a) b) Arrangement (b) c) Both d) Neither The bulb will light in arrangement A in which the filament of the bulb is connected to the two sides of the battery for a closed circuit. In B there is no voltage across the filament and thus no current in the filament.

10 ! Water flowing in a pipe is similar to electric current flowing in a circuit. # The battery is like the pump. # The electric charge is like the water. # The connecting wires are like the thick pipe. # The filament is like the nozzle or narrow pipe. # The switch is like the valve.

11 ! In a water-flow system, a high pressure difference will produce a large rate of water flow or current. # High pressure can be produced by raising the storage tank: this pressure is related to the gravitational potential energy. # Likewise, a large difference in potential energy between the charges at the two ends of a battery is associated with a high voltage and a greater tendency for charge to flow.

12 In the circuit shown, the wires are connected to either side of a wooden block as well as to the light bulb. Will the light bulb light in this arrangement? a) Yes b) No c) Maybe d) Impossible to tell from the picture The bulb will not light since (dry) wood is a very poor conductor. The resistance will be so high that virtually no current is in the lamp circuit.

13 In the circuit shown, could we increase the brightness of the bulb by connecting a wire between points A and B? a) Yes b) No c) Maybe d) Impossible to tell from the picture No. Connecting A and B will provide a short circuit for the battery that will damage it while allowing virtually no current in the bulb.

14 Which of the two circuits shown will cause the light bulb to light? a) Arrangement (a) b) Arrangement (b) c) Both d) Neither Diagram B will allow the light bulb to light since there is a closed circuit providing current from the battery through the bulb. Whether the switch is open or closed is immaterial here since it is in parallel with another conductor. In diagram A no potential difference is in the closed circuit.

15 Suppose we use an uncoated metal clamp to hold the wires in place in the battery-and-bulb circuit shown. Will this be effective in keeping the bulb burning brightly? a) Yes b) No c) Maybe d) Impossible to tell from the picture No. The metal clamp will provide a conducting path across the battery causing the battery to discharge. If we want to use a clamp we can put insulating tape between one of its jaws and the electrical connection.

16 Ohm s Law and Resistance! The electric current flowing through a given portion of a circuit is directly proportional to the voltage difference across that portion and inversely proportional to the resistance: Ohm's Law : I = "V R # Resistance R is the ratio of the voltage difference to the current for a given portion of a circuit, and is in units of ohms: 1 ohm = 1! = 1 V / A. # The resistance of a wire is proportional to the length of the wire, inversely proportional to the cross-sectional area of the wire, and inversely proportional to the conductivity of the material. # It also depends on the temperature of the material.

17 Consider the two signs shown, located in different physics labs. Which of the two would be reason for greater concern? a) The one on the left. b) The one on the right. c) Both d) Neither We had better pay attention to the high voltage warning. The other is a practical joke. The danger to the body, and even to life, comes from electrical current in the body, which could occur if you accidentally make contact with a large potential difference across parts of your body. The effect of a high resistance is to limit current in a circuit if a voltage source is present; it is not dangerous at all.

18 ! If we know the resistance of a given portion of a circuit and the applied voltage, we can calculate the current through that portion of the circuit. "For example, consider a 1.5-V battery connected to a light bulb with a resistance of 20 ohms. "If the resistance of the battery itself is negligible, the current can be found by applying Ohm s Law: I = 1.5 V / 20! = A = 75 ma

19 ! However, we ignored the resistance of the battery itself, as well as the very small resistance of the connecting wires. # If the battery is fresh, its internal resistance is small and can often be neglected. # As the battery is used, its internal resistance gets larger. "The voltage of the battery, 1.5 V, is called the electromotive force!: the increase in potential energy per unit charge provided by the chemical reactions in the battery. "Loop equation:! = I R

20 "If the internal resistance of the battery is 5!, then the total resistance of the circuit is: R = R battery + R bulb = 5! + 20! = 25! "Then the total current in the circuit is: I =! / R = 1.5 V / 25! = 0.06 A = 60 ma "And the voltage difference across the light bulb is: "V = I R = (0.06 A)(20!) = 1.2 V "If we measure the voltage difference across the battery or the light bulb, we will get 1.2 V.

21 "If we disconnect the bulb and measure the voltage across the battery terminals, we will get 1.5 V again. "As a battery gets older, its internal resistance gets larger. "The total resistance of the circuit increases and reduces the current flowing through the circuit. "As the current gets smaller, the bulb gets dimmer. "In a dead battery, the internal resistance has become so large that the battery can no longer produce a measurable current. "A good voltmeter does not draw much current, so it can still measure approximately the electromotive force of the battery, even if the battery has too much internal resistance to produce a measurable current.

22 Series and Parallel Circuits! In a series circuit, there are no points in the circuit where the current can branch into secondary loops. # All the elements line up on a single loop. # The current that passes through one element must also pass through the others.

23 ! In a series combination of resistances, each resistance contributes to restricting the flow of current around the loop. # The total series resistance of the combination R series is the sum of the individual resistances: R series = R 1 + R 2 + R 3 # A common mistake is to think the current gets used up in passing through the resistances in a series circuit. # The same current must pass through each component much like the continuous flow of water in a pipe.

24 ! It is the voltage that changes as the current flows through the circuit. # Voltage decreases by Ohm s Law: "V = I R as the current passes through each resistor.! The total voltage difference across the combination is the sum of these individual changes. # If two light bulbs are connected in series with a battery, the current will be less than with a single bulb, because the total series resistance is larger. # The bulbs will glow less brightly.

25 Two resistors are connected in series with a battery as shown. R 1 is less than R 2. Which of the two resistors has the greater current flowing through it? a) R 1 b) R 2 c) Both d) Neither The current is the same in each, since it is a series circuit.

26 Two resistors are connected in series with a battery as shown. R 1 is less than R 2. Which of the two resistors has the greatest voltage difference across it? a) R 1 b) R 2 c) Both d) Neither The voltage difference is greater across R 2. According to Ohm's Law, V = IR, so for the same current, the larger the resistance the greater the potential difference.

27 In the circuit shown, the 1-! resistance is the internal resistance of the battery and can be considered to be in series with the battery and the 9-! load. What is the current flowing through the 9-! resistor? a) 0.1 A b) 0.3 A c) 0.9 A d) 3 A e) 10 A R series = 9 " + 1 " = 10 " I series = V total R series = 3 V 10 " = 0.3 A

28 In the circuit shown, the 1-! resistance is the internal resistance of the battery and can be considered to be in series with the battery and the 9-! load. What is the voltage across the 9-! resistor? a) 0.1 V b) 0.3 V c) 1.0 V d) 2.7 V e) 3.0 V since I 9" = I series : V 9" = I series R 9" = ( 0.3 A) ( 9 ") = 2.7 V

29 Three resistors are connected to a 6-V battery as shown. The internal resistance of the battery is negligible. What is the current through the 15-! resistance? a) 0.1 A b) 0.15 A c) 0.4 A d) 1.5 A e) 4.0 A R series = 15 " + 20 " + 25 " = 60 " I 15" = I series = V total R series = 6 V 60 " = 0.1 A

30 Does this same current flow through the 25-! resistance? a) Yes. b) No. c) It depends on various things. Yes. Since all the resistors are in series, the same current must flow through all three. There is no other path for the current through the 15-! resistor to follow, except to go through the 20-! resistor and then the 25-! resistor.

31 What is the voltage difference across the 25-! resistance? a) 0.1 V b) 2.5 V c) 6 V d) 25 V e) 60 V since I 25" = I series : V 25" = I series R 25" = ( 0.1 A) ( 25 ") = 2.5 V

32 ! In a parallel circuit, there are points at which the current can branch or split up into different paths. # The flow divides and later rejoins. # The total cross-sectional area the current (or water) flows through is increased, therefore decreasing the resistance to flow: 1 R parallel = 1 R R R 3

33 ! In a parallel combination of resistances, the voltage difference across each resistance is the same, since they are all connected between the same two points. # The currents can be different, since they divide: they add to give the total current through the combination. # A portion of the total current flows through each branch.

34 ! Parallel combinations decrease the resistance and increase the amount of current that will flow.! Increased current causes the bulbs to burn more brightly than in a series circuit but also depletes the batteries more quickly.! The energy available from the batteries is the same in either case.

35 Two 10-! light bulbs are connected in parallel to one another, and this combination is connected to a 6-V battery. What is the total current flowing around the loop? a) 0.6 A b) 1.2 A c) 6 A d) 12 A e) 60 A 1 R parallel = 1 R R 2 = 1 10 " " = 2 10 " = 1 5 " I = " R = 6 V 5 # = 1.2 A R parallel = 5 "

36 How much current passes through each light bulb? a) 0.6 A b) 1.2 A c) 6 A d) 12 A e) 60 A I = "V R = 6 V 10 # = 0.6 A

37 Three identical resistors, each 24!, are connected in parallel with one another as shown. The combination is connected to a 12-V battery whose internal resistance is negligible. What is the equivalent resistance of this parallel combination? a) ! b) 0.125! c) 8! d) 24! e) 72! 1 R parallel = 1 R R R 3 = 1 24 " " " = 3 24 " = 1 8 " R parallel = 8 "

38 What is the total current through the combination? a) 0.5 V b) 1.0 V c) 1.2 V d) 1.5 V e) 12 V I total = V total R parallel = 12 V 8 " = 1.5 V

39 How much current flows through each resistor in the combination? a) 0.5 V b) 1.0 V c) 1.2 V d) 1.5 V e) 12 V The resistors are identical and are in parallel, so the same current must flow through each resistor. The total current is plit into three identical parts : I one 24 -" resistor = 1 3 I total = 1 ( V ) = 0.5 V

40 In the circuit shown, R 3 is greater than R 2, and R 2 is greater than R 1.! is the electromotive force of the battery whose internal resistance is negligible. Which of the three resistors has the greatest current flowing through it? a) R 1 b) R 2 c) R 3 d) R 1 and R 2 are equal, and greater than R 3 e) They are all equal R 3 has the greatest current since the current in it is the sum of the currents in R 1 and R 2.

41 ! A voltmeter measures the voltage difference between two points in a circuit, or across an element in a circuit # It is inserted in parallel with the element whose voltage difference is being measured. # A voltmeter should have a large resistance, so that it does not divert much current from the component whose voltage is being measured.

42 In the circuit shown, the circle with a V in it represents a voltmeter. Which of the following statements is correct? a) The voltmeter is in the correct position for measuring the voltage difference across R. b) No current will flow through the meter, so it will have no effect. c) The meter will draw a large current. The correct statement is (a). A voltmeter is a highresistance device connected in parallel with whatever circuit element it is desired to measure the voltage across.

43 ! An ammeter measures the electric current flowing through a point in a circuit. # It is inserted in series into the circuit whose current is being measured, so that all the current flows through it. # An ammeter should have a small resistance, so that its effect on the current is small. # If you place an ammeter directly across the terminals of a battery, you could damage the meter and the battery.

44 In the circuit shown, the circle with an A in it represents an ammeter. Which of the following statements is correct? a) The meter is in the correct position for measuring the current through R. b) No current will flow through the meter, so it will have no effect. c) The meter will draw a significant current from the battery. The answer is (c). An ammeter is a low-resistance device and is to be placed in series in the circuit, just as a flowmeter is placed in a fluid circuit.

45 Electric Energy and Power! Energy is supplied to a water-flow system by the pump, which increases the gravitational potential energy of the water by lifting it up to a higher tank. "As the water flows down through pipes to a lower tank, gravitational potential energy is transformed into kinetic energy of the moving water. "Once the water comes to rest in the lower tank, the kinetic energy is dissipated by frictional or viscous forces which generate heat.

46 ! Similarly, in an electric circuit energy is supplied by a battery, which draws its energy from the potential energy stored in its chemical reactants. # The battery increases the potential energy of electric charges as it moves positive charges toward the positive terminal and negative charges toward the negative terminal. # When we provide an external conducting path from the positive to the negative terminal, charge flows from points of higher potential energy to points of lower potential energy. "As potential energy is lost, kinetic energy is gained by the electrons. "This kinetic energy is converted to heat by collisions with other electrons and atoms.

47 Energy source # potential energy # kinetic energy # heat! Since voltage is potential energy per unit charge, multiplying a voltage difference by charge yields energy.! Since current is the rate of flow of charge, multiplying a voltage difference by current yields power, the rate of energy use.! The power supplied by a source must equal the power dissipated in the resistances. P ="I = #VI; #V = IR \$ P = (IR)R = I 2 R "I = I 2 R

48 What is the power dissipated in a 20-! light bulb powered by two 1.5-V batteries in series? a) 0.15 W b) 0.45 W c) 3.0 W d) 6.67 W e) 60 W " =" 1 +" 2 = 3 V R = 20 # " = IR I = " R = 3 V 20 # = 0.15 A check : P ="I = I 2 R = (0.15 A) 2 (20 #) = 0.45 W P ="I = (3 V)(0.15 A) = 0.45 W

49 ! The ease with which electric power can be transmitted over considerable distances is one of its main advantages over other forms of energy. # The source of the energy might be gravitational potential energy of water, chemical potential energy stored in fossil fuels, or nuclear potential energy stored in uranium. # Power plants all use electric generators that convert mechanical kinetic energy produced by turbines to electric energy. # These generators are the source of the electromotive force.

50 ! The unit of energy commonly used to discuss electric energy is the kilowatt-hour, which is a unit of power (the kilowatt) multiplied by a unit of time (an hour). # 1 kilowatt equals 1000 watts # 1 hour = 3600 seconds # 1 kilowatt-hour equals 3.6 million joules! The kilowatt-hour is a much larger unit of energy than the joule, but it is a convenient size for the amounts of electrical energy typically used in a home.

51 How much does it cost to light a 100-watt light bulb for one day? Assume an average rate of cost of 10 cents per kilowatt-hour. a) 0.24 cents b) 2.4 cents c) 24 cents d) \$2.40 e) \$24 Energy used = power x time Cost = energy used x rate of cost = (100 W)(24 hr) = (2.4 kwh)(10 cents / kwh) = 2400 Wh = (2.4 kwh)(10 cents / kwh) = 2.4 kwh = 24 cents

52 Alternating Current and Household Circuits! The current we draw from a wall outlet is alternating current (ac) rather than direct current (dc). # Direct current implies that the current flows in a single direction from the positive terminal of a battery or power supply to the negative terminal # Alternating current continually reverses its direction -- it flows first in one direction, then in the other, then back again. # In North America the ac goes through 60 cycles each second (60 Hz).

53 ! The plot of electric current as a function of time for an alternating current is a sinusoidal curve. # The average value of an ordinary alternating current is zero. # The power dissipated in a resistance is proportional to the square of the current. # The effective current or rms current is obtained by squaring the current, averaging this value over time, and taking the square root of the result. # The effective current I eff is times the peak current I peak.

54 ! If we plot the voltage across an electrical outlet as a function of time, we get another sinusoidal curve. # The effective value of this voltage is typically between 110 and 120 volts in North America. # The standard household power supplied in this country is 115 volts, 60 hertz ac. # Household circuits are wired in parallel so that different appliances can be added to or removed from the circuit without affecting the voltage available.

55 A 60-W light bulb is designed to operate on 120 V ac. What is the effective current drawn by the bulb? a) 0.2 A b) 0. 5 A c) 2.0 A d) 72 A e) 7200 A P = 60 W "V effective = 120 V P = I"V # I = P "V = 60 W 120 V = 0.5 A

56 ! Household circuits are wired in parallel so that different appliances can be added to or removed from the circuit without affecting the voltage available. # As you add more appliances, the total current drawn increases, because the total effective resistance of the circuit decreases when resistances are added in parallel. # Since too large a current could cause the wires to overheat, a fuse or circuit breaker in series with one leg of the circuit will disrupt the circuit if the current gets too large. # Appliances with larger power requirements (stoves, clothes dryers, etc) are usually connected to a separate 220-V line.

### Magnets and the Magnetic Force

Magnets and the Magnetic Force We are generally more familiar with magnetic forces than with electrostatic forces. Like the gravitational force and the electrostatic force, this force acts even when the

### Chapter 13: Electric Circuits

Chapter 13: Electric Circuits 1. A household circuit rated at 120 Volts is protected by a fuse rated at 15 amps. What is the maximum number of 100 watt light bulbs which can be lit simultaneously in parallel

### Science AS90191 Describe Aspects of Physics.

Circuits and components Science AS90191 Describe Aspects of Physics. An electric current is the movement of electrons (negatively charged particles). A circuit is made up of components connected together

### Chapter 11- Electricity

Chapter 11- Electricity Course Content Definition of Electricity Circuit Diagrams Series and Parallel Circuits Calculating total resistances Measurement of Electricity Ammeters and Voltmeters Ohm s Law

### 7. What is the current in a circuit if 15 coulombs of electric charge move past a given point in 3 seconds? (1) 5 A (3) 18 A (2) 12 A (4) 45 A

1. Compared to the number of free electrons in a conductor, the number of free electrons in an insulator of the same volume is less the same greater 2. Most metals are good electrical conductors because

### Objectives 200 CHAPTER 4 RESISTANCE

Objectives Explain the differences among conductors, insulators, and semiconductors. Define electrical resistance. Solve problems using resistance, voltage, and current. Describe a material that obeys

### Electrostatics. Electrostatics Version 2

1. A 150-watt lightbulb is brighter than a 60.-watt lightbulb when both are operating at a potential difference of 110 volts. Compared to the resistance of and the current drawn by the 150-watt lightbulb,

### Series and Parallel Circuits

Series and Parallel Circuits Components in a circuit can be connected in series or parallel. A series arrangement of components is where they are inline with each other, i.e. connected end-to-end. A parallel

### Electrical Fundamentals Module 3: Parallel Circuits

Electrical Fundamentals Module 3: Parallel Circuits PREPARED BY IAT Curriculum Unit August 2008 Institute of Applied Technology, 2008 ATE310- Electrical Fundamentals 2 Module 3 Parallel Circuits Module

### The current that flows is determined by the potential difference across the conductor and the resistance of the conductor (Ohm s law): V = IR P = VI

PHYS1000 DC electric circuits 1 Electric circuits Electric current Charge can move freely in a conductor if an electric field is present; the moving charge is an electric current (SI unit is the ampere

### Chapter 5. Electrical Energy

Chapter 5 Electrical Energy Our modern technological society is largely defined by our widespread use of electrical energy. Electricity provides us with light, heat, refrigeration, communication, elevators,

### Ch. 20 Electric Circuits

Ch. 0 Electric Circuits 0. Electromotive Force Every electronic device depends on circuits. Electrical energy is transferred from a power source, such as a battery, to a device, say a light bulb. Conducting

### People s Physics Book

The Big Ideas: The name electric current is given to the phenomenon that occurs when an electric field moves down a wire at close to the speed of light. Voltage is the electrical energy density (energy

### Chapter 17 Study Questions Name: Class:

Chapter 17 Study Questions Name: Class: Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. 1. If two charges repel each other, the two charges

### CHAPTER 17 NOTES FOR EIGHTH GRADE PHYSICAL SCIENCE ALL MATTER IS COMPOSED OF VERY SMALL PARTICLES CALLED ATOMS.

CHAPTER 17 NOTES FOR EIGHTH GRADE PHYSICAL SCIENCE ALL MATTER IS COMPOSED OF VERY SMALL PARTICLES CALLED ATOMS. THE LAW OF ELECTRIC CHARGES STAES THAT LIKE CHARGES REPEL AND OPPOSITE CHARGES ATTRACT. BECAUSE

### EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 1 - D.C. CIRCUITS

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME - D.C. CIRCUITS Be able to use circuit theory to determine voltage, current and resistance in direct

### Q1. (a) The diagram shows the voltage-current graphs for three different electrical components.

Q. (a) The diagram shows the voltage-current graphs for three different electrical components. Which one of the components A, B or C could be a 3 volt filament lamp? Explain the reason for your choice...................

### PS-6.2 Explain the factors that determine potential and kinetic energy and the transformation of one to the other.

PS-6.1 Explain how the law of conservation of energy applies to the transformation of various forms of energy (including mechanical energy, electrical energy, chemical energy, light energy, sound energy,

### Chapter 18: Circuits and Circuit Elements 1. Schematic diagram: diagram that depicts the construction of an electrical apparatus

Chapter 18: Circuits and Circuit Elements 1 Section 1: Schematic Diagrams and Circuits Schematic Diagrams Schematic diagram: diagram that depicts the construction of an electrical apparatus Uses symbols

### Two kinds of electrical charges

ELECTRICITY NOTES Two kinds of electrical charges Positive charge Negative charge Electrons are negatively charged Protons are positively charged The forces from positive charges are canceled by forces

### How Does it Flow? Electricity, Circuits, and Motors

How Does it Flow? Electricity, Circuits, and Motors Introduction In this lab, we will investigate the behavior of some direct current (DC) electrical circuits. These circuits are the same ones that move

### Resistors in Series and Parallel

Resistors in Series and Parallel Bởi: OpenStaxCollege Most circuits have more than one component, called a resistor that limits the flow of charge in the circuit. A measure of this limit on charge flow

### I = V/r P = VI. I = P/V = 100 W / 6 V = 16.66 amps. What would happen if you use a 12-volt battery and a 12-volt light bulb to get 100 watts of power?

Volts, Amps and Ohms Measuring Electricity The three most basic units in electricity are voltage (V), current (I) and resistance (r). Voltage is measured in volts, current is measured in amps and resistance

### STUDY GUIDE: ELECTRICITY AND MAGNETISM

319 S. Naperville Road Wheaton, IL 60187 www.questionsgalore.net Phone: (630) 580-5735 E-Mail: info@questionsgalore.net Fax: (630) 580-5765 STUDY GUIDE: ELECTRICITY AND MAGNETISM An atom is made of three

1 ANSWERS to CIRCUITS 1. The speed with which electrons move through a copper wire is typically 10-4 m s -1. a. Explain why is it that the electrons cannot travel faster in the conductor? b. Explain why

### PHYSICS 111 LABORATORY Experiment #3 Current, Voltage and Resistance in Series and Parallel Circuits

PHYSCS 111 LABORATORY Experiment #3 Current, Voltage and Resistance in Series and Parallel Circuits This experiment is designed to investigate the relationship between current and potential in simple series

### Student Exploration: Circuits

Name: Date: Student Exploration: Circuits Vocabulary: ammeter, circuit, current, ohmmeter, Ohm s law, parallel circuit, resistance, resistor, series circuit, voltage Prior Knowledge Questions (Do these

### Circuits. PHY2049: Chapter 27 1

Circuits PHY2049: Chapter 27 1 What You Already Know Nature of current Current density Drift speed and current Ohm s law Conductivity and resistivity Calculating resistance from resistivity Power in electric

### Circuits and Resistivity

Circuits and Resistivity Look for knowledge not in books but in things themselves. W. Gilbert OBJECTIVES To learn the use of several types of electrical measuring instruments in DC circuits. To observe

### Electricity CHAPTER 12 12.1 ELECTRIC CURRENT AND CIRCUIT

CHAPTER 12 Electricity Electricity has an important place in modern society. It is a controllable and convenient form of energy for a variety of uses in homes, schools, hospitals, industries and so on.

### very small Ohm s Law and DC Circuits Purpose: Students will become familiar with DC potentiometers circuits and Ohm s Law. Introduction: P31220 Lab

Ohm s Law and DC Circuits Purpose: Students will become familiar with DC potentiometers circuits and Ohm s Law. Introduction: Ohm s Law for electrical resistance, V = IR, states the relationship between

### ELECTRICAL CIRCUITS. Electrical Circuits

Electrical Circuits A complete path, or circuit, is needed before voltage can cause a current flow through resistances to perform work. There are several types of circuits, but all require the same basic

### SIMPLE ELECTRIC CIRCUITS

-18- Preparatory Questions: (also read this guide sheet, which contains some of the answers!) 1. State Ohm s Law, defining every term in the equation. 2. If a bulb connected directly to a 6 V battery glows

### Solutions to Bulb questions

Solutions to Bulb questions Note: We did some basic circuits with bulbs in fact three main ones I can think of I have summarized our results below. For the final exam, you must have an understanding of

### Electric Potential Difference

Name: Electric Potential Difference Read from Lesson 1 of the Current Electricity chapter at The Physics Classroom: http://www.physicsclassroom.com/class/circuits/u9l1a.html http://www.physicsclassroom.com/class/circuits/u9l1b.html

### Question Bank. Electric Circuits, Resistance and Ohm s Law

Electric Circuits, Resistance and Ohm s Law. Define the term current and state its SI unit. Ans. The rate of flow of charge in an electric circuit is called current. Its SI unit is ampere. 2. (a) Define

### Series and Parallel Circuits

Series and Parallel Circuits Direct-Current Series Circuits A series circuit is a circuit in which the components are connected in a line, one after the other, like railroad cars on a single track. There

### 1) ASSOCIATE ELEMENTARY PARTICLES WITH THEIR ELECTRICAL CHARGE

Name Date STUDY GUIDE CHAPTER 5 ELECTRICITY AND MAGNETISM 1) ASSOCIATE ELEMENTARY PARTICLES WITH THEIR ELECTRICAL CHARGE Scientists now know that an atom is composed of even smaller particles of matter:

### Ohm's Law and Circuits

2. Conductance, Insulators and Resistance A. A conductor in electricity is a material that allows electrons to flow through it easily. Metals, in general, are good conductors. Why? The property of conductance

### Section B: Electricity

Section B: Electricity We use mains electricity, supplied by power stations, for all kinds of appliances in our homes, so it is very important to know how to use it safely. In this chapter you will learn

### Circuit symbol. Each of the cells has a potential difference of 1.5 volts. Figure 1. Use the correct answer from the box to complete the sentence.

Q.(a) Draw one line from each circuit symbol to its correct name. Circuit symbol Name Diode Light-dependent resistor (LDR) Lamp Light-emitting diode (LED) (3) Figure shows three circuits. The resistors

### Experiment #6, Series and Parallel Circuits, Kirchhoff s Laws

Physics 182 Spring 2013 Experiment #6 1 Experiment #6, Series and Parallel Circuits, Kirchhoff s Laws 1 Purpose Our purpose is to explore and validate Kirchhoff s laws as a way to better understanding

### Shining a Light. Design & Technology. Year 9. Structure of an electric torch. Shining a Light

Looking at electronic circuits and what is meant by current, voltage, and resistance. Shining a Light Have you ever taken an electric torch to pieces to find out how it works? Look at the diagram below

### AP1 Electricity. 1. A student wearing shoes stands on a tile floor. The students shoes do not fall into the tile floor due to

1. A student wearing shoes stands on a tile floor. The students shoes do not fall into the tile floor due to (A) a force of repulsion between the shoes and the floor due to macroscopic gravitational forces.

### Resistors in Series and Parallel

OpenStax-CNX module: m42356 1 Resistors in Series and Parallel OpenStax College This work is produced by OpenStax-CNX and licensed under the Creative Commons Attribution License 3.0 Abstract Draw a circuit

### Electricity Review-Sheet

Name: ate: 1. The unit of electrical charge in the MKS system is the. volt. ampere. coulomb. mho 2. Which sketch best represents the charge distribution around a neutral electroscope when a positively

### 101 BASICS SERIES LEARNING MODULE 2: FUNDAMENTALS OF ELECTRICITY. Cutler-Hammer

101 BASICS SERIES LEARNING MODULE 2: FUNDAMENTALS OF ELECTRICITY Cutler-Hammer WELCOME Welcome to Module 2, Fundamentals of Electricity. This module will cover the fundamentals of electricity in a practical

### Chapter 7 Direct-Current Circuits

Chapter 7 Direct-Current Circuits 7. Introduction...7-7. Electromotive Force...7-3 7.3 Resistors in Series and in Parallel...7-5 7.4 Kirchhoff s Circuit Rules...7-7 7.5 Voltage-Current Measurements...7-9

### CHAPTER 19: DC Circuits. Answers to Questions

HAPT 9: D ircuits Answers to Questions. The birds are safe because they are not grounded. Both of their legs are essentially at the same voltage (the only difference being due to the small resistance of

### Note-A-Rific: Characteristics

Note-A-Rific: Characteristics Any path along which electrons can flow is a circuit. For a continuous flow of electrons, there must be a complete circuit with no gaps. A gap is usually an electric switch

### Electrical Circuit Calculations

Electrical Circuit Calculations Series Circuits Many circuits have more than one conversion device in them (i.e. toaster. heater. lamps etc.) and some have more than one source of electrical energy. If

### Kirchhoff's Rules and Applying Them

[ Assignment View ] [ Eðlisfræði 2, vor 2007 26. DC Circuits Assignment is due at 2:00am on Wednesday, February 21, 2007 Credit for problems submitted late will decrease to 0% after the deadline has passed.

### Lecture Notes: ECS 203 Basic Electrical Engineering Semester 1/2010. Dr.Prapun Suksompong 1 June 16, 2010

Sirindhorn International Institute of Technology Thammasat University School of Information, Computer and Communication Technology Lecture Notes: ECS 203 Basic Electrical Engineering Semester 1/2010 Dr.Prapun

### Lab E1: Introduction to Circuits

E1.1 Lab E1: Introduction to Circuits The purpose of the this lab is to introduce you to some basic instrumentation used in electrical circuits. You will learn to use a DC power supply, a digital multimeter

### Experiment NO.3 Series and parallel connection

Experiment NO.3 Series and parallel connection Object To study the properties of series and parallel connection. Apparatus 1. DC circuit training system 2. Set of wires. 3. DC Power supply 4. Digital A.V.O.

### The diagram shows a negatively charged plastic rod held near to a thin stream of water. The water is attracted towards the rod.

Current electricity exam qs C grade Madeley High School Q.(a) The diagram shows a negatively charged plastic rod held near to a thin stream of water. The water is attracted towards the rod. Which one of

### Experiment #5, Series and Parallel Circuits, Kirchhoff s Laws

Physics 182 Summer 2013 Experiment #5 1 Experiment #5, Series and Parallel Circuits, Kirchhoff s Laws 1 Purpose Our purpose is to explore and validate Kirchhoff s laws as a way to better understanding

### Georgia Performance Standards Framework for Physical Science 8 th Grade. Powering Satellites

The following instructional plan is part of a GaDOE collection of Unit Frameworks, Performance Tasks, examples of Student Work, and Teacher Commentary. Many more GaDOE approved instructional plans are

### Experiment #3, Ohm s Law

Experiment #3, Ohm s Law 1 Purpose Physics 182 - Summer 2013 - Experiment #3 1 To investigate the -oltage, -, characteristics of a carbon resistor at room temperature and at liquid nitrogen temperature,

### Chapter 14 Magnets and

Chapter 14 Magnets and Electromagnetism How do magnets work? What is the Earth s magnetic field? Is the magnetic force similar to the electrostatic force? Magnets and the Magnetic Force! We are generally

### Student Content Brief Advanced Level

Student Content Brief Advanced Level Electric Circuits Background Information There are a variety of forces acting on the body of the Sea Perch. One important force is pushing electrons through the wires

### ELECTRICITY (E) So, what is this mysterious stuff that we call E? Where does it come from? Where does it go and why is it

ELECTRICITY (E) Electricity how it works, how we measure and pay for it. INTRODUCTION: HOW ELECTRICITY WORKS: E completely surrounds us. Modern life would be rather primitive without it. A few examples

### Unit 7: Electric Circuits

Multiple Choice Portion 1. The diagram below shows part of an electrical circuit. Unit 7: Electric Circuits 4. A 12 V battery supplies a 5.0 A current to two light bulbs as shown below. What are the magnitude

### ElectronicsLab2.nb. Electronics Lab #2. Simple Series and Parallel Circuits

Electronics Lab #2 Simple Series and Parallel Circuits The definitions of series and parallel circuits will be given in this lab. Also, measurements in very simple series and parallel circuits will be

### Forms of Energy. Freshman Seminar

Forms of Energy Freshman Seminar Energy Energy The ability & capacity to do work Energy can take many different forms Energy can be quantified Law of Conservation of energy In any change from one form

### Lab 3 - DC Circuits and Ohm s Law

Lab 3 DC Circuits and Ohm s Law L3-1 Name Date Partners Lab 3 - DC Circuits and Ohm s Law OBJECTIES To learn to apply the concept of potential difference (voltage) to explain the action of a battery in

### 1. The diagram below represents magnetic lines of force within a region of space.

1. The diagram below represents magnetic lines of force within a region of space. 4. In which diagram below is the magnetic flux density at point P greatest? (1) (3) (2) (4) The magnetic field is strongest

### AP Physics Electricity and Magnetism #4 Electrical Circuits, Kirchoff s Rules

Name Period AP Physics Electricity and Magnetism #4 Electrical Circuits, Kirchoff s Rules Dr. Campbell 1. Four 240 Ω light bulbs are connected in series. What is the total resistance of the circuit? What

### Temperature coefficient of resistivity

Temperature coefficient of resistivity ρ slope = α ρ = ρ o [ 1+ α(t To )] R = R o [1+ α(t T o )] T T 0 = reference temperature α = temperature coefficient of resistivity, units of (ºC) -1 For Ag, Cu, Au,

### Vocabulary Electrical Energy Negative charge Electric Field Conductor Insulator Voltage Current Circuit breaker Fuse. Chapter 17.

Introduction to Electricity Table of Contents Bellringer Write a definition for electric charge in your own words in your science journal. When do you experience electric charges most, in winter or in

### S E C T I O N O N E : I N T R O D U C T I O N

S E C T I O N O N E : I N T R O D U C T I O N What you will learn: What electricity is What an electrical current is How electricity is created How electricity is used to perform useful tasks The physical

### 13.10: How Series and Parallel Circuits Differ pg. 571

13.10: How Series and Parallel Circuits Differ pg. 571 Key Concepts: 5. Connecting loads in series and parallel affects the current, potential difference, and total resistance. - Using your knowledge of

### FREQUENTLY ASKED QUESTIONS October 2, 2012

FREQUENTLY ASKED QUESTIONS October 2, 2012 Content Questions Why do batteries require resistors? Well, I don t know if they require resistors, but if you connect a battery to any circuit, there will always

### Fig. 1 Analogue Multimeter Fig.2 Digital Multimeter

ELECTRICAL INSTRUMENT AND MEASUREMENT Electrical measuring instruments are devices used to measure electrical quantities such as electric current, voltage, resistance, electrical power and energy. MULTIMETERS

### Series and Parallel Circuits

Direct Current (DC) Direct current (DC) is the unidirectional flow of electric charge. The term DC is used to refer to power systems that use refer to the constant (not changing with time), mean (average)

### Physics 133: tutorial week 4 Ohm s law, electrical power, emf and internal resistance.

Physics 133: tutorial week 4 Ohm s law, electrical power, emf and internal resistance. 41. The heating element of a clothes drier has a resistance of 11Ïand is connected across a 240V electrical outlet.

### Introduction to Electricity & Magnetism. Dr Lisa Jardine-Wright Cavendish Laboratory

Introduction to Electricity & Magnetism Dr Lisa Jardine-Wright Cavendish Laboratory Examples of uses of electricity Christmas lights Cars Electronic devices Human body Electricity? Electricity is the presence

### Electronics. Basic Concepts. Yrd. Doç. Dr. Aytaç GÖREN Yrd. Doç. Dr. Levent ÇETİN

Electronics Basic Concepts Electric charge Ordinary matter is made up of atoms which have positively charged nuclei and negatively charged electrons surrounding them. Charge is quantized as the subtraction

### Answer, Key Homework 11 David McIntyre 1 1 A

nswer, Key Homework 11 avid Mcntyre 1 This print-out should have 36 questions, check that it is complete. Multiple-choice questions may continue on the next column or page: find all choices before making

### CHAPTER 28 ELECTRIC CIRCUITS

CHAPTER 8 ELECTRIC CIRCUITS 1. Sketch a circuit diagram for a circuit that includes a resistor R 1 connected to the positive terminal of a battery, a pair of parallel resistors R and R connected to the

### Chapter 7. DC Circuits

Chapter 7 DC Circuits 7.1 Introduction... 7-3 Example 7.1.1: Junctions, branches and loops... 7-4 7.2 Electromotive Force... 7-5 7.3 Electrical Energy and Power... 7-9 7.4 Resistors in Series and in Parallel...

### Basic Principles of. Electricity. Basic Principles of Electricity. by Prof. Dr. Osman SEVAİOĞLU Electrical and Electronics Engineering Department

Basic Principles of Electricity METU by Prof. Dr. Osman SEVAİOĞLU Electrical and Electronics Engineering Department EE 209 Fundamentals of Electrical and Electronics Engineering, Prof. Dr. O. SEVAİOĞLU,

### 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

### BUILDING A BASIC CIRCUIT

Teacher Information BUILDING A BASIC CIRCUIT NSES9-12.2 Physical Science: Interactions of Energy and Matter Adaptations Some adaptations and modifications that may assist a student with visual and/or other

### Objectives. Electric Current

Objectives Define electrical current as a rate. Describe what is measured by ammeters and voltmeters. Explain how to connect an ammeter and a voltmeter in an electrical circuit. Explain why electrons travel

### PHYSICS REFERENCE STUDY MATERIAL. for. Summative Assessment -I CLASS X 2014 15 CHAPTER WISE CONCEPTS, FORMULAS AND NUMERICALS INLCUDING HOTS PROBLEMS

PHYSICS REFERENCE STUDY MATERIAL for Summative Assessment -I CLASS X 2014 15 CHAPTER WISE CONCEPTS, FORMULAS AND NUMERICALS INLCUDING HOTS PROBLEMS Prepared by M. S. KUMARSWAMY, TGT(MATHS) M. Sc. Gold

### Section 1 Current and Circuits: Practice Problems

Section 1 Current and Circuits: Practice Problems 1. A car battery causes a current through a lamp and produces 12 V across it as shown in Figure 4. What is the power used by the lamp? P = IV = (2.0 A)(12

### Odyssey of the Mind Technology Fair. Simple Electronics

Simple Electronics 1. Terms volts, amps, ohms, watts, positive, negative, AC, DC 2. Matching voltages a. Series vs. parallel 3. Battery capacity 4. Simple electronic circuit light bulb 5. Chose the right

### GENERATORS AND MOTORS

GENERATORS AND MOTORS A device that converts mechanical energy (energy of motion windmills, turbines, nuclear power, falling water, or tides) into electrical energy is called an electric generator. The

### OHM S LAW AND RESISTANCE

OHM S LAW AND RESISTANCE Resistance is one of the basic principles of Ohm s law, and can be found in virtually any device used to conduct electricity. Georg Simon Ohm was a German physicist who conducted

### Resistance, Ohm s Law, and the Temperature of a Light Bulb Filament

Resistance, Ohm s Law, and the Temperature of a Light Bulb Filament Name Partner Date Introduction Carbon resistors are the kind typically used in wiring circuits. They are made from a small cylinder of

### Light Bulbs in Parallel Circuits

Light Bulbs in Parallel Circuits In the last activity, we analyzed several different series circuits. In a series circuit, there is only one complete pathway for the charge to travel. Here are the basic

### CAPACITIVE REACTANCE. We have already discussed the operation of a capacitor in a DC circuit, however let's just go over the main principles again.

Reading 13 Ron Bertrand VK2DQ http://www.radioelectronicschool.com CAPACITOR IN A DC CIRCUIT CAPACITIVE REACTANCE We have already discussed the operation of a capacitor in a DC circuit, however let's just

### Current, Resistance and Electromotive Force. Young and Freedman Chapter 25

Current, Resistance and Electromotive Force Young and Freedman Chapter 25 Electric Current: Analogy, water flowing in a pipe H 2 0 gallons/minute Flow Rate is the NET amount of water passing through a

### Series and Parallel Resistive Circuits Physics Lab VIII

Series and Parallel Resistive Circuits Physics Lab VIII Objective In the set of experiments, the theoretical expressions used to calculate the total resistance in a combination of resistors will be tested

### Schematic diagrams depict the construction of a circuit Uses symbols to represent specific circuit elements Documents how elements are connected so

Circuits Schematic diagrams depict the construction of a circuit Uses symbols to represent specific circuit elements Documents how elements are connected so that anyone reading diagram can understand the

### Voltage Drop (Single-Phase)

Voltage Drop (Single-Phase) To Find: To Find Voltage Drop Formula: 2 x K x L x I V.D. = ------------------- C.M. Variables: C.M. = Circular Mill Area (Chapter 9, Table 8) To Find Voltage Drop Percentage

### Power Ranger: Monitoring Electrical Appliances

Power Ranger: Monitoring Electrical Appliances Outcomes: 1. Understand how to use a power monitoring meter to measure line voltage, current, and power consumption. 2. Understand the difference between

### Electricity & Electronics 8: Capacitors in Circuits

Electricity & Electronics 8: Capacitors in Circuits Capacitors in Circuits IM This unit considers, in more detail, the charging and discharging of capacitors. It then investigates how capacitors behave