# 12. Transformers, Impedance Matching and Maximum Power Transfer

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 1 1. Transformers, Impedance Matching and Maximum Power Transfer Introduction The transformer is a device that takes AC at one voltage and transforms it into another voltage either higher or lower than the original voltage. Alternatively, a transformer can be used to do the same thing with current. Transformers only work with AC (and they do not work with DC) because they work on the principle of Faraday's law of induction which involves time varying magnetic flux. Transformers are useful in electronics because (for example) the voltage supplied by the electric utility is voltages while the voltage used by transistors and integrated circuits is typically a much lower (say 10-1 volts). Additionally transformers can be used to isolate a circuit from the ground in which case the transformer is called an "isolation transformer". Isolation transformer typically have the same number of turns in the primary and secondary coils since there is no need to increase or decrease the voltage when a transformer is used to isolate a circuit. Finally, transformers can also be used to "impedance match" a power supply with a load to maximize the power transferred to the load. Power supplies have an internal resistance and even something as simple as a battery has an internal resistance which dissipates part of the power generated. This power is wasted since it does not do anything useful. We will show that the maximum power a power supply to transfer to a load resistor is when the load resistance equals the internal resistance of the power supply. Unfortunately, often the load resistor does not equal the internal resistance of the power supply but a transformer can be used to make the effective resistance of the load equal to the power supply and maximum power transfer is achieved. The Results of Transformers Theory The basic transformer is two coils wound on an iron core like the diagram below:

2 One of the coils is connected to the AC source of voltage V p (or current I p ) and this coil is called the primary coil. Also suppose the primary coil has N p turns of wire. The load is attached to the secondary coil which we will assume has turns and the voltage across the secondary as measured by a voltmeter is Vs (or an ammeter will measure current Is ). The basic transformer equation is Vp Vs = (1) and this is easy to remember as the voltage is proportional to the number of turns. Equation (1) is a result of Faraday's law of induction and this is the reason transformers work only with AC. A transformers is called a "voltage step-up transformers" if the secondary voltage Vs is greater than the primary voltage V p. For Vs > V p the ratio of the turns is from equation (1) tells us that > N p. Similarly, a transformers is called a "voltage step-down transformers" if the secondary voltage Vs is less than the primary voltage V p. For Vs < V p the ratio of the turns is from equation (1) tells us that < N p. Transformer conserve energy and power (they do not make energy) if they are ideal. Since Power P=I V it follows that if a transformer is voltage step-up, then it must also be current step down. (Or if the transformer is voltage step-down, it is current step-up.) The equation for current corresponding to equation (1) is Ip Is = () So the current is inversely proportional to the number of turns. If we are lucky the manufacturer of a transformer publishes the ratio of turns for the transformer r = N p. For example, you might be given that r= or the primary has twice the turns as the secondary. Using this with equation (1) you get

3 3 Vp Vs = r (3) and thus Vs = Vp (4) r So for example, if Vp =10 volts the equation (4) tells us that Vs =10/=60 volts. If we are unlucky and we do not have r the ratio of the turns, we can measure the resistance of the primary R p and the resistance of the secondary Rs and assuming the length of the wire is proportional to the resistance and that the primary and secondary are the same kind of wire (have the same cross sectional area) we can conclude r= Rp (5) Rs The calculation of equation (3) and (4) follows as before. Mostly the transformers we use have the same kind of wire for the primary and secondary. In fact, the only thing that distinguishes the primary from the secondary of the transformer is which coil is connected to the voltage source (this will be the primary) and which coil is connected to the load (and this is called the secondary). For example, the source voltage and load can be reversed in the above transformer so that the ratio of turns r=1/ (instead of r=). Then using equation (3) and (4) with for example, 10 if Vp =10 volts, the equation (4) tells us that Vs = 0.5 = 10 =40 volts. Either or both the primary and secondary may be "center tapped" which means the primary coil has a wire running out of the center of the coil. This might be used in constructing certain power supplies like a full wave power supply. Laboratory Exercises PART A: You will be supplied with a transformer and using the resistance argument above together with equation (5), measure the ratio of turns r. Attach your SIGNAL GENERATOR in sine wave mode to the primary and set the amplitude say at 1 volts as measured on your oscilloscope. Attach a load resistor something like R=5,000 ohms to the secondary and measure the voltage across the load. Use equation (4) to calculate the secondary voltage. Your theoretical prediction should agree pretty much with the experiment. PART B: Reverse the voltage source and load as attached to the transformer of PART A. Measure the primary voltage and secondary voltage and see if the ratio agrees with your prediction from equation (4) and equation (5).

4 PART B: Reverse the voltage source and load as attached to the transformer of PART A. Measure the primary voltage and secondary voltage and see if the ratio agrees with your prediction from equation (4) and equation (5). PART C: One of the coils of your transformer is probably center-tapped. Measure the resistance from one end of the coil to the center and see if this is the same as the resistance from the other end to the center. If the two resistances are the same it is safe to assume the coil is divided into two equal parts having the same number of turns. Use the center tapped coil as the secondary and use only half of the coil (that use the part of the coil from one end to the center). Calculate the ratio of turns r using equation (5). Repeat PART A above with the only difference being that you are using only half of the secondary coil. PART D: Try to repeat PART A using the 1 volt DC power supply on your circuit box. What happens? The Use of a Transformer to Isolate a Circuit from Ground Consider a RLC circuit indicated below: The signal generator output has a ground as indicated above. This also grounds one side of the inductor L inadvertently. If you use an oscilloscope to measure the voltage across the inductor L, you must attached the center of the probe of the oscilloscope to the top of the inductor L since the outer conductor of the coaxial cable is automatically grounded. Therefore with only one wire attached from the oscilloscope, you measure the voltage across the inductor because the other wire need in the circuit is the ground. This arrangement is unsatisfactory since if you want to measure the voltage across the resistor R, you must interchange the resistor R and inductor L in the above circuit and then attach the oscilloscope probe to the top of the resistor. If you do not interchange the resistor R and inductor L if you attach the oscilloscope probe to the other side of the resistor, the voltage measured by the oscilloscope actually is the sum of the voltage across the resistor and the voltage across the inductor. 4

5 of the coaxial cable is automatically grounded. Therefore with only one wire attached from the oscilloscope, you measure the voltage across the inductor because the other wire need in the circuit is the ground. This arrangement is unsatisfactory since if you want to measure the voltage across the resistor R, you must interchange the resistor R and inductor L in the above circuit and then attach the oscilloscope probe to the top of the resistor. If you do not interchange the resistor R and inductor L if you attach the oscilloscope probe to the other side of the resistor, the voltage measured by the oscilloscope actually is the sum of the voltage across the resistor and the voltage across the inductor. The difficulty with the above circuit can be removed by using an isolation transformer as indicated by the circuit below: The ground of the oscilloscope and the ground of the signal generator are as indicated. Notice that until the outer coaxial cable of the probe of the oscilloscope is attached as indicated, the oscilloscope will NOT measure any voltage. Without the ground of the coaxial cable attached, there is not a complete circuit which is necessary to measure the voltage across the inductor. The isolation transformer isolates the ground of the signal generator from the ground of the oscilloscope. If you want to measure the voltage across the resistor, you now do NOT need the interchange the resistor R and inductor L in the above circuit. You need simply attach the oscilloscope leads across the resistor. Laboratory Exercise Build the above RLC circuit with the isolation transformer. Use the values of R, L, and C you used in Lab #11 on Resonance. Show that you can measure the voltage across the inductor L ONLY IF you attach the oscilloscope leads across the inductor L. Show that you can measure the voltage across the resistor R by attaching the oscilloscope leads across the resistor R. 5

6 6 Build the above RLC circuit with the isolation transformer. Use the values of R, L, and C you used in Lab #11 on Resonance. Show that you can measure the voltage across the inductor L ONLY IF you attach the oscilloscope leads across the inductor L. Show that you can measure the voltage across the resistor R by attaching the oscilloscope leads across the resistor R. The Maximum Power Transfer from a Power Supply to a Load Resistor Consider a power supply connected to a load resistor as indicated by the diagram below: The signal generator has an internal resistance as indicated and this is an intrinsic part of the power supply. The current in the above circuit is using Ohm's law I= V HRLoad + Rinternal (6) The power transferred to the load resistor from the power supply is PLoad = I RLoad (7) and the power dissipated by the internal resistance of the power supply is Pinternal = I Rinternal (8) Imagine you can adjust the load resistor until you get the maximum power transferred to the load. That is PL is a function of RL and we adjust RL until PL is a maximum. Calculus can be used to search for the value of RL that makes PL by taking the derivative

7 7 Imagine you can adjust the load resistor until you get the maximum power transferred to the load. That is PL is a function of RL and we adjust RL until PL is a maximum. Calculus can be used to search for the value of RL that makes PL by taking the derivative dpl d RL =0 (9) and solving for RL. Combine equation (6) in equation (7) and obtain PL = V (10) RL RL + RI Using Mathematica to compute the derivative yields (calling RL simply R and RI we call RI) V * R HR + RI L R - R V HR + RIL3 + V HR + RIL H-R + RIL V HR + RIL3 The solving for R yields SolveB H- R + RIL V HR + RIL3 Š 0, 8R<F 88R RI<< The solution to the equation is R=RI. What this says is that the power transferred to the load PL is a maximum when the load resistance R (or what we previously called RL ) is equal to RI (what we previously called RI the internal resistance). When R=RI half the power of the supply is transferred to the load resistor and but half the power is lost to the internal resistance. The maximum efficiency achieved by a power supply is 50% which is kind of disappointing but true. Rint = RL for maximum power transfer (11) Laboratory Exercise Attach a load resistor RLoad as indicated in the circuit above and measure the voltage of the signal generator and the voltage across the resistor using an oscilloscope. Start with a load resistor in the neighborhood of PL = VL RL. RLoad = 5, 000 W. Calculate the power transferred to the load resistor using Next pick a new load resistor say for example RLoad = 10, 000 W and measure the voltage across the load resistor and calculate the power transferred to the load resistor using PL = VL RL. Make sure the voltage provided by the signal generator is the same as before by attaching the oscilloscope across the

8 Attach a load resistor RLoad as indicated in the circuit above and measure the voltage of the signal generator and the voltage across the resistor using an oscilloscope. Start with a load resistor in the neighborhood of PL = VL RL. RLoad = 5, 000 W. Calculate the power transferred to the load resistor using Next pick a new load resistor say for example RLoad = 10, 000 W and measure the voltage across the load resistor and calculate the power transferred to the load resistor using PL = VL RL. Make sure the voltage provided by the signal generator is the same as before by attaching the oscilloscope across the signal generator. If the voltage of the signal generator has changed, adjust the output level of the signal generator. Repeat the above for increasing values of RL using 0,000W, 40,000W, 100,000 W and 1,000,000 W load resistor. Compute the power transferred to the load resistor in each case. Graph PL versus RL. Your graph should have a peak and that peak will occur when RL = Rint. This is a method of determining the internal resistance of a power supply. The Effective Resistance of a Load Resistance attached to a Transformer Consider a transformer connected between the load resistor and the power supply as indicated below: 8

9 9 Assume the transformer is ideal so that the resistance of the windings is small compared with the load resistor and internal resistance of the power supply. Suppose an ammeter is placed in the secondary circuit and Is is measured and a voltmeter (or oscilloscope since you are measuring AC) placed across the secondary reads Vs. Ohm's law holds for the secondary circuit so Vs = Is RLoad (1) A voltmeter (oscilloscope) attached across the primary coil would read V p and this is different from the voltage of the signal generator V0 because there is a voltage drop I p RI across the internal resistance. We can write V0 = Ip RI + Vp (13) The voltage of the primary V p is related to the voltage of the secondary Vs via equation (1) so Vp = Vs (14)

10 10 and using equation (11) for the voltage of the secondary Vs in equation (13) yields Vp = Is RLoad (15) However, the secondary current Is in equation (14) is related to the primary current I p via equation () so Is = Ip (16) Finally utilizing equation (15) in equation (14) yields Vp = (17) Ip RLoad which just seems like a complicated equation. However, if you use equation (16) to eliminate V p in equation (1) you obtain V0 = Ip RI + Ip RLoad (18) or more simply after factoring I p from both terms V0 = Ip RI + RLoad (19) Equation (18) should be interpreted as Ohm's law for the primary circuit where you have two resistors in series. One resistor is RI the internal resistance of the power supply (or signal generator). The other series resistor is effectively Reff = RLoad (0) so equation (18) appears simply V0 = Ip HRI + Reff L (1) What equation (19) and (0) are saying is that as far as the primary circuit is concerned, the load resistor RL has an effective resistance given by equation (18). We know from the maximum power transfer theorem that when RI = Reff the maximum power is transferred from the signal generator to the load resistor. In a practical situation RLoad is the resistance of a speaker or head phone or even the resistance of a light bulb and RLoad cannot be adjusted for the maximum power transfer since RLoad is an intrinsic property of the speaker, head phone, or light bulb. None-the-less maximum power can be transferred by using a transformer with the ratio of turns r=n p chosen properly. What this means is that for a given RL choose a transformer with a ratio r such that Reff calculate from equation (19) namely Reff = r RLoad is such that Rint = Reff. Then maximum power transfer to the load is achieved. This is called impedance (or resistance) matching since the load resistance is matched to the internal resistance using a transformer to achieve maximum power transfer.

11 Load Load property of the speaker, head phone, or light bulb. None-the-less maximum power can be transferred by using a transformer with the ratio of turns r=n p chosen properly. What this means is that for a given RL choose a transformer with a ratio r such that Reff calculate from equation (19) namely Reff = r RLoad is such that Rint = Reff. Then maximum power transfer to the load is achieved. This is called impedance (or resistance) matching since the load resistance is matched to the internal resistance using a transformer to achieve maximum power transfer. A Numerical Example of Impedance Matching Suppose your power supply has an internal resistance RInt = 0 W but you want to attach to a load resistor having resistance RLoad =, 000 W. (Think of your power supply as an amiplfier and the load resistance as headphones attached to your amplifier.) Design a transformer that will enable the maximum power to be trasferred to your head phones. ANSWER: You know from equation (11) that maximum power transfer occurs when Reff = Rint = 0 W. You also know from equation (19) that the effective resistance seen by the power supply is Reff = r RL = r 000 W. Combining these two equations yields 0W=Reff = r 000 W so solving for r we obtain r = 0 W 000 W=1/100 and r=1/10 is the turns ratio. 11

### Chapter 14. Transformers ISU EE. C.Y. Lee

Chapter 14 Transformers Objectives Explain mutual inductance Describe how a transformer is constructed and how it works Explain how a step-up and -down transformer works Discuss the effect of a resistive

### UNIVERSITY of PENNSYLVANIA DEPARTMENT of ELECTRICAL and SYSTEMS ENGINEERING ESE206 - Electrical Circuits and Systems II Laboratory.

UNIVERSITY of PENNSYLVANIA DEPARTMENT of ELECTRICAL and SYSTEMS ENGINEERING ESE06 - Electrical Circuits and Systems II Laboratory. Objectives: Transformer Lab. Comparison of the ideal transformer versus

### Questions. Question 1

Question 1 Questions Explain why transformers are used extensively in long-distance power distribution systems. What advantage do they lend to a power system? file 02213 Question 2 Are the transformers

### 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

### Circuits with inductors and alternating currents. Chapter 20 #45, 46, 47, 49

Circuits with inductors and alternating currents Chapter 20 #45, 46, 47, 49 RL circuits Ch. 20 (last section) Symbol for inductor looks like a spring. An inductor is a circuit element that has a large

### 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

### LRC Circuits. Purpose. Principles PHYS 2211L LAB 7

Purpose This experiment is an introduction to alternating current (AC) circuits. Using the oscilloscope, we will examine the voltage response of inductors, resistors and capacitors in series circuits driven

### Transformer circuit calculations

Transformer circuit calculations This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/,

### Magnetism and Electromagnetic Induction Generators and Transformers

PHSC 101 Lab Magnetism and Electromagnetic Induction Generators and Transformers Objectives: - Explore a magnetic field. - Demonstrate electromagnetic induction with a magnet and a coil of wire. - Demonstrate

### ElectronicsLab5.nb. Electronics Lab #5. Thevenin's Theorem

Electronics Lab #5 Thevenin's Theorem Often you deal with a complicated electronic circuit. It is often the case that the behavior of one particular component is crucial. For example, you could have an

### Transformers. What is a transformer?

Transformers What is a transformer? A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors the transformer's coils. A physical and

### Inductors in AC Circuits

Inductors in AC Circuits Name Section Resistors, inductors, and capacitors all have the effect of modifying the size of the current in an AC circuit and the time at which the current reaches its maximum

### PHYS 2426 Engineering Physics II (Revised July 7, 2011) AC CIRCUITS: RLC SERIES CIRCUIT

PHYS 2426 Engineering Physics II (Revised July 7, 2011) AC CIRCUITS: RLC SERIES CIRCUIT INTRODUCTION The objective of this experiment is to study the behavior of an RLC series circuit subject to an AC

### Magnetic Flux (primary) = Magnetic Flux (secondary) Eq 2

Transformers Electrical transformers are used to transform voltage or current. The basic arrangement is shown in Figure 1 and 2 below. The best a transformer can do is to transfer all of the electrical

### 13. Diode Rectifiers, Filters, and Power Supplies

1 13. Diode Rectifiers, Filters, and Power Supplies Introduction A power supply takes Alternating Current or A.C. power from your electric utility (Con Edison) and converts the A.C. electrical current

### BASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS LECTURE-4 SOME USEFUL LAWS IN BASIC ELECTRONICS

BASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS LECTURE-4 SOME USEFUL LAWS IN BASIC ELECTRONICS Hello everybody! In a series of lecture on basic electronics, learning by doing, we now

### RLC Series Resonance

RLC Series Resonance 11EM Object: The purpose of this laboratory activity is to study resonance in a resistor-inductor-capacitor (RLC) circuit by examining the current through the circuit as a function

### Electromagnetic Induction

Electromagnetic Induction "Concepts without factual content are empty; sense data without concepts are blind... The understanding cannot see. The senses cannot think. By their union only can knowledge

### Name Date Day/Time of Lab Partner(s) Lab TA

Name Date Day/Time of Lab Partner(s) Lab TA Objectives LAB 7: AC CIRCUITS To understand the behavior of resistors, capacitors, and inductors in AC Circuits To understand the physical basis of frequency-dependent

### Basic Electronics Prof. Dr. Chitralekha Mahanta Department of Electronic and Communication Engineering Indian Institute of Technology, Guwahati

Basic Electronics Prof. Dr. Chitralekha Mahanta Department of Electronic and Communication Engineering Indian Institute of Technology, Guwahati Module -5 Power Circuits and System Lecture - 2 Transformer

### Input and Output Impedances of Resistive Circuits

Input and Output Impedances of Resistive Circuits Last time we saw that according to Thevinin s Theorem and Norton s Theorem, any kind of signal source (which we have arbitrarily modeled as a network of

### Impedance Matching and Matching Networks. Valentin Todorow, December, 2009

Impedance Matching and Matching Networks Valentin Todorow, December, 2009 RF for Plasma Processing - Definition of RF What is RF? The IEEE Standard Dictionary of Electrical and Electronics Terms defines

### Ohm s Law. 1 Object. 2 Apparatus. 3 Theory. To study resistors, Ohm s law, linear behavior, and non-linear behavior.

Ohm s Law Object To study resistors, Ohm s law, linear behavior, and non-linear behavior. pparatus esistors, power supply, meters, wires, and alligator clips. Theory resistor is a circuit element which

### Application Note. So You Need to Measure Some Inductors?

So You Need to Measure Some nductors? Take a look at the 1910 nductance Analyzer. Although specifically designed for production testing of inductors and coils, in addition to measuring inductance (L),

### Properties of electrical signals

DC Voltage Component (Average voltage) Properties of electrical signals v(t) = V DC + v ac (t) V DC is the voltage value displayed on a DC voltmeter Triangular waveform DC component Half-wave rectifier

### Eðlisfræði 2, vor 2007

[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 31. Alternating Current Circuits Assignment is due at 2:00am on Wednesday, March 21, 2007 Credit for problems submitted late will decrease to 0% after the

### THE TRANSFORMER. REFERENCES: PASCO Transformer Notes Physics for Scientists and Engineers, Tipler, 4 th Ed., Vol. 2 INTRODUCTION.

THE TRANSFORMER LAB ELEC 7 REFERENCES: PASCO Transformer Notes Physics for Scientists and Engineers, Tipler, 4 th Ed., Vol. 2 NTRODUCTON Nearly all of today s electrical energy is produced as alternating

### 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)

### EE 221 Circuits II. Chapter 13 Magnetically Coupled Circuits

EE Circuits II Chapter 3 Magnetically Coupled Circuits Magnetically Coupled Circuits 3. What is a transformer? 3. Mutual Inductance 3.3 Energy in a Coupled Circuit 3.4 inear Transformers 3.5 Ideal Transformers

### Saturday X-tra X-Sheet: 19. Electric circuits

Saturday X-tra X-Sheet: 9 Key Concepts Electric circuits This lesson focuses on the following: Potential Difference Current The resistance of a conductor Ohm s Law and circuit calculations Terminology

### Coupled Inductors. Introducing Coupled Inductors

Coupled Inductors From power distribution across large distances to radio transmissions, coupled inductors are used extensively in electrical applications. Their properties allow for increasing or decreasing

### Chapter 3. Simulation of Non-Ideal Components in LTSpice

Chapter 3 Simulation of Non-Ideal Components in LTSpice 27 CHAPTER 3. SIMULATION OF NON-IDEAL COMPONENTS IN LTSPICE 3.1 Pre-Lab The answers to the following questions are due at the beginning of the lab.

### EXPERIMENT 4:- MEASUREMENT OF REACTANCE OFFERED BY CAPACITOR IN DIFFERENT FREQUENCY FOR R-C CIRCUIT

Kathmandu University Department of Electrical and Electronics Engineering BASIC ELECTRICAL LAB (ENGG 103) EXPERIMENT 4:- MEASUREMENT OF REACTANCE OFFERED BY CAPACITOR IN DIFFERENT FREQUENCY FOR R-C CIRCUIT

### INTRODUCTION SELF INDUCTANCE. Introduction. Self inductance. Mutual inductance. Transformer. RLC circuits. AC circuits

Chapter 13 INDUCTANCE Introduction Self inductance Mutual inductance Transformer RLC circuits AC circuits Magnetic energy Summary INTRODUCTION Faraday s important contribution was his discovery that achangingmagneticflux

### The full wave rectifier consists of two diodes and a resister as shown in Figure

The Full-Wave Rectifier The full wave rectifier consists of two diodes and a resister as shown in Figure The transformer has a centre-tapped secondary winding. This secondary winding has a lead attached

### Chapt ha e pt r e r 12 RL Circuits

Chapter 12 RL Circuits Sinusoidal Response of RL Circuits The inductor voltage leads the source voltage Inductance causes a phase shift between voltage and current that depends on the relative values of

### SINGLE PHASE TRANSFORMER MAGNETIC CIRCUIT AND ELECTRIC TRANSFORMER PART1: FAMILIARIZATION

Islamic University of Gaza Faculty of Engineering Electrical Engineering department Electric Machine Lab Eng. Omar A. Qarmout Eng. Amani S. Abu Reyala Experiment 3 SINGLE PHASE TRANSFORMER MAGNETIC CIRCUIT

### Chapter 2 Objectives

Chapter 2 Engr228 Circuit Analysis Dr Curtis Nelson Chapter 2 Objectives Understand symbols and behavior of the following circuit elements: Independent voltage and current sources; Dependent voltage and

### 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

### Charge and Discharge of a Capacitor

Charge and Discharge of a Capacitor INTRODUCTION Capacitors 1 are devices that can store electric charge and energy. Capacitors have several uses, such as filters in DC power supplies and as energy storage

### Student Name Instructor Name. High School or Vocational Center Grade. COMPETENCY RECORD FOR ARTICULATION Muskegon Community College Electronics

Student Name Instructor Name High School or Vocational Center Grade COMPETENCY RECORD FOR ARTICULATION Muskegon Community College Electronics Please check below each skill the student has mastered as described,

### MAGNETISM MAGNETISM. Principles of Imaging Science II (120)

Principles of Imaging Science II (120) Magnetism & Electromagnetism MAGNETISM Magnetism is a property in nature that is present when charged particles are in motion. Any charged particle in motion creates

### Electrical Resonance

Electrical Resonance (R-L-C series circuit) APPARATUS 1. R-L-C Circuit board 2. Signal generator 3. Oscilloscope Tektronix TDS1002 with two sets of leads (see Introduction to the Oscilloscope ) INTRODUCTION

### Circuits. Page The diagram below represents a series circuit containing three resistors.

Name: Circuits Date: 1. Which circuit segment has an equivalent resistance of 6 ohms? 4. The diagram below represents a series circuit containing three resistors. 2. Base your answer to the following question

### Faraday s and Lenz s Law: Induction

Lab #18 Induction page 1 Faraday s and Lenz s Law: Induction Reading: Giambatista, Richardson, and Richardson Chapter 20 (20.1-20.9). Summary: In order for power stations to provide electrical current

### Single phase, uncontrolled rectification (conversion)

Single phase, uncontrolled rectification (conversion) J Charles Lee Doyle C12763425 29 October 2015 Abstract An experiment investigating full wave rectification, for the purposes of producing a steady

### CURRENT ELECTRICITY INTRODUCTION TO RESISTANCE, CAPACITANCE AND INDUCTANCE

CURRENT ELECTRICITY INTRODUCTION TO RESI STANCE, CAPACITANCE AND INDUCTANCE P R E A M B L E This problem is adapted from an on-line knowledge enhancement module for a PGCE programme. It is used to cover

### Direct versus Alternating Current Things We Can Measure

Phil Sherrod W4PHS Direct versus Alternating Current Things We Can Measure Direct Current (DC) Alternating Current (AC) Voltage Voltage (peak, RMS) Current Current (peak, effective) Power True power, Apparent

### Laboratory #2: AC Circuits, Impedance and Phasors Electrical and Computer Engineering EE University of Saskatchewan

Authors: Denard Lynch Date: Aug 30 - Sep 28, 2012 Sep 23, 2013: revisions-djl Description: This laboratory explores the behaviour of resistive, capacitive and inductive elements in alternating current

### PHY 101 Lab 7 on Electric circuits: Direct current circuits Your name: Other team members:

PHY 101 Lab 7 on Electric circuits: Direct current circuits Your name: Other team members: Goals: To explore the basic principles of electric circuits, and how to measure them. Materials: Electrical resistors

### PROCEDURE: 1. Measure and record the actual values of the four resistors listed in Table 10-1.

The answer to two questions will help you identify a series or parallel connection: (1) Will the identical current go through both components? f the answer is yes, the components are in series. (2) Are

### 3_given a graph of current_voltage for a resistor, determine the resistance. Three resistance R1 = 1.0 kω, R2 = 1.5 kω, R3 = 2.

Ohm s Law Objectives: 1_measure the current_voltage curve for a resistor 2_construct a graph of the data from objective 1 3_given a graph of current_voltage for a resistor, determine the resistance Equipment:

### 2. TRANSFORMERS. The main learning objectives for this chapter are listed below. Use equivalent circuits to determine voltages and currents.

. TRANSFORMERS Transformers are commonly used in applications which require the conversion of AC voltage from one voltage level to another. There are two broad categories of transformers: electronic transformers,

### WHY DIFFERENTIAL? instruments connected to the circuit under test and results in V COMMON.

WHY DIFFERENTIAL? Voltage, The Difference Whether aware of it or not, a person using an oscilloscope to make any voltage measurement is actually making a differential voltage measurement. By definition,

### ELECTRICITY & ELECTROMAGNETISM TRANSFORMERS + ETC

Circuitry, Formulas & Electricity Ch5 Bushong RT 244 12 Lect # 3 1 RT 244 WEEK 10 rev 2012 2 LECTURE # 3 ELECTRICITY & ELECTROMAGNETISM TRANSFORMERS + ETC BUSHONG CH. 4 & 5 REF: CARLTONS CH 3, 4 & 5 &

### Voltage Transformers. VT Types

Voltage Transformers VT - Voltage Transformer, also know as Potential Transformer (PT) CVT - Capacitive Voltage Transformer also know as CCVT (Capacitive Coupled VT) BPD - Bushing Potential Device also

### Basic Electrical Theory

Basic Electrical Theory Impedance PJM State & Member Training Dept. PJM 2014 10/24/2013 Objectives Identify the components of Impedance in AC Circuits Calculate the total Impedance in AC Circuits Identify

### Practice Problems - Chapter 33 Alternating Current Circuits

Multiple Choice Practice Problems - Chapter 33 Alternating Current Circuits 4. A high-voltage powerline operates at 500 000 V-rms and carries an rms current of 500 A. If the resistance of the cable is

### physics 112N electromagnetic induction

physics 112N electromagnetic induction experimental basis of induction! seems we can induce a current in a loop with a changing magnetic field physics 112N 2 magnetic flux! useful to define a quantity

### ECE 2201 PRELAB 2 DIODE APPLICATIONS

ECE 2201 PRELAB 2 DIODE APPLICATIONS P1. Review this experiment IN ADVANCE and prepare Circuit Diagrams, Tables, and Graphs in your notebook, prior to coming to lab. P2. Hand Analysis: (1) For the zener

### CIRCUITS AND SYSTEMS LABORATORY EXERCISE 6 TRANSIENT STATES IN RLC CIRCUITS AT DC EXCITATION

CIRCUITS AND SYSTEMS LABORATORY EXERCISE 6 TRANSIENT STATES IN RLC CIRCUITS AT DC EXCITATION 1. DEVICES AND PANELS USED IN EXERCISE The following devices are to be used in this exercise: oscilloscope HP

### EE 1202 Experiment #4 Capacitors, Inductors, and Transient Circuits

EE 1202 Experiment #4 Capacitors, Inductors, and Transient Circuits 1. Introduction and Goal: Exploring transient behavior due to inductors and capacitors in DC circuits; gaining experience with lab instruments.

### Eðlisfræði 2, vor 2007

[ Assignment View ] [ Print ] Eðlisfræði 2, vor 2007 30. Inductance Assignment is due at 2:00am on Wednesday, March 14, 2007 Credit for problems submitted late will decrease to 0% after the deadline has

### 1) 10. V 2) 20. V 3) 110 V 4) 220 V

1. The diagram below represents an electric circuit consisting of a 12-volt battery, a 3.0-ohm resistor, R 1, and a variable resistor, R 2. 3. What is the total resistance of the circuit 1) 6.6 Ω 2) 10

### STUDY OF IDEAL TRANSFORMER AND PRACTICAL TRANSFORMER

STUDY OF IDEAL TRANSFORMER AND PRACTICAL TRANSFORMER RUBY DHANKAR, SAPNA KAMRA,VISHAL JANGRA Abstract- This paper proposes the study of real and ideal transformer. It also explains load, no-load conditions

### PH102 Lab: Mutual Inductance. Consider two coaxial solenoids, one inside the other, a situation we discussed recently in lecture:

Group member s names: For this lab, you will need: PH10 Lab: Mutual Inductance 1 - function generator 1 - hand-held multimeter 1 - pair of coaxial solenoids 4 - banana cables 1 - male BNC to banana plug

### 45. The peak value of an alternating current in a 1500-W device is 5.4 A. What is the rms voltage across?

PHYS Practice Problems hapters 8- hapter 8. 45. The peak value of an alternating current in a 5-W device is 5.4 A. What is the rms voltage across? The power and current can be used to find the peak voltage,

### Lecture 24. Inductance and Switching Power Supplies (how your solar charger voltage converter works)

Lecture 24 Inductance and Switching Power Supplies (how your solar charger voltage converter works) Copyright 2014 by Mark Horowitz 1 Roadmap: How Does This Work? 2 Processor Board 3 More Detailed Roadmap

### Rectifier Circuits. A. Half-wave (HW) Rectifier. By: Al Christman Grove City College 100 Campus Drive Grove City, PA

Rectifier Circuits By: Al Christman Grove City College 100 Campus Drive Grove City, PA Rectifiers are used to convert AC to pulsating DC, and can be combined with various types of filters to form power

### The Ideal Transformer. Description and Circuit Symbol

The Ideal Transformer Description and Circuit Symbol As with all the other circuit elements, there is a physical transformer commonly used in circuits whose behavior can be discussed in great detail. However,

### Basic Electrical Theory

Basic Electrical Theory Power Principles and Phase Angle PJM State & Member Training Dept. PJM 2014 10/24/2013 Objectives At the end of this presentation the learner will be able to; Identify the characteristics

### ε: Voltage output of Signal Generator (also called the Source voltage or Applied

Experiment #10: LR & RC Circuits Frequency Response EQUIPMENT NEEDED Science Workshop Interface Power Amplifier (2) Voltage Sensor graph paper (optional) (3) Patch Cords Decade resistor, capacitor, and

### Chapter 5 TRANSFORMERS

Chapter 5 TRANSFORMERS Objective Understand the transformer nameplate Describe the basic construction features of a transformer. Explain the relationship between voltage, current, impedance, and power

### Lab 1: DC Circuits. Student 1, student1@ufl.edu Partner : Student 2, student2@ufl.edu

Lab Date Lab 1: DC Circuits Student 1, student1@ufl.edu Partner : Student 2, student2@ufl.edu I. Introduction The purpose of this lab is to allow the students to become comfortable with the use of lab

### RADIO AMATEUR EXAM GENERAL CLASS

RAE-Lessons by 4S7VJ 1 RADIO AMATEUR EXAM GENERAL CLASS By 4S7VJ CHAPTER- 3 3.1 REACTANCE (X) When a.c. voltage applied to a capacitor or an inductor the current (r.m.s.) is proportional to the voltage

### EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 4 - ALTERNATING CURRENT 4 Understand single-phase alternating current (ac) theory Single phase AC

10. A ircuits* Objective: To learn how to analyze current and voltage relationships in alternating current (a.c.) circuits. You will use the method of phasors, or the vector addition of rotating vectors

### Goals. Introduction R = DV I (7.1)

Lab 7. Ohm s Law Goals To understand Ohm s law, used to describe the behavior of electrical conduction in many materials and circuits. To calculate the electrical power dissipated as heat in electrical

### Chapter 11. Inductors. Objectives

Chapter 11 Inductors Objectives Describe the basic structure and characteristics of an inductor Discuss various types of inductors Analyze series inductors Analyze parallel inductors Analyze inductive

### Transformer Calculations

Transformer Calculations Transformers Transformers are one of the most basic yet practical devices used today. No matter where you are there is always a transformer nearby. They are used throughout alternating-current

### Electric Circuits Review

Electric Circuits Review 1. Which of the following statements are true about electric current? Circle all that apply. a. Electric current is measured in units of Amperes. b. Electric current is defined

### Ohms Law I--DC Circuits with Light Bulbs PhET Lab I with Ammeters and Voltmeters

Ohms Law I--DC Circuits with Light Bulbs PhET Lab I with Ammeters and Voltmeters by Dr. James E. Parks Department of Physics and Astronomy 401 Nielsen Physics Building The University of Tennessee Knoxville,

### Electricity. Voltage and current transformation with a transformer. LD Physics Leaflets P Electromagnetic induction Transformer

Electricity Electromagnetic induction Transformer LD Physics Leaflets Voltage and current transformation with a transformer P3.4.5. Objects of the experiment g Measuring the secondary voltage of an unloaded

### Teacher s Guide Physics Labs with Computers, Vol C P52: LRC Circuit. Teacher s Guide - Activity P52: LRC Circuit (Voltage Sensor)

Teacher s Guide Physics Labs with Computers, Vol. 2 012-06101C P52: LRC Circuit Teacher s Guide - Activity P52: LRC Circuit (Voltage Sensor) Concept DataStudio ScienceWorkshop (Mac) ScienceWorkshop (Win)

### Diodes have an arrow showing the direction of the flow.

The Big Idea Modern circuitry depends on much more than just resistors and capacitors. The circuits in your computer, cell phone, Ipod depend on circuit elements called diodes, inductors, transistors,

### Circuits-Circuit Analysis

Base your answers to questions 1 through 3 on the information and diagram below. 4. A 9-volt battery is connected to a 4-ohm resistor and a 5-ohm resistor as shown in the diagram below. A 3.0-ohm resistor,

### Lab 3. Transistor and Logic Gates

Lab 3. Transistor and Logic Gates Laboratory Instruction Today you will learn how to use a transistor to amplify a small AC signal as well as using it as a switch to construct digital logic circuits. Introduction

### 15. Transistor Amplifier Design and Measurement

1 15. Transistor Amplifier Design and Measurement Introduction The previous module was devoted to measuring the characteristics of a transistor. In particular, you measured the amplification parameter

### POWER AMPLIFIERS 15.1 INTRODUCTION-DEFINITONS AND AMPLIFIER TYPES

POWER AMPLIFIERS 15.1 INTRODUCTION-DEFINITONS AND AMPLIFIER TYPES An Amplifier receives a signal from some pickup transducer or other input source and provides a larger version of the signal to some output

### Current and resistance

Current and resistance Electrical resistance Voltage can be thought of as the pressure pushing charges along a conductor, while the electrical resistance of a conductor is a measure of how difficult it

### Extra Questions - 1. 1. What current will flow in a 20Ω resistor when it is connected to a 50V supply? a) 0.4A b) 1.6A c) 2.5A

Extra Questions - 1 1. What current will flow in a 20Ω resistor when it is connected to a 50V supply? a) 0.4A b) 1.6A c) 2.5A 2. A current of 500mA flows in a resistance of 12Ω. What power is dissipated

### Section 4. Ohm s Law: Putting up a Resistance. What Do You See? What Do You Think? Investigate. Learning Outcomes

Section 4: Ohm s Law: Putting up a Resistance Section 4 Ohm s Law: Putting up a Resistance What Do You See? Learning Outcomes In this section, you will Calculate the resistance of an unknown resistor given

### Transformer Basics Information Guide

Property of Motion Laboratories, Inc. Transformer Basics Information Guide 2014 Motion Laboratories, Inc. Created By: Jim Herrick / Michael Shaw Approved By: Peter Herrmann Page: 1 Transformer Definition

### Experiment 3 ~ Ohm's Law, Measurement of Voltage, Current and Resistance

Experiment 3 ~ Ohm's Law, Measurement of Voltage, Current and Resistance Objective: In this experiment you will learn to use the multi-meter to measure voltage, current and resistance. Equipment: Bread

### Lab #4 Capacitors and Inductors. Capacitor and Inductor Transient Response

Capacitor and Inductor Transient Response Capacitor Theory Like resistors, capacitors are also basic circuit elements. Capacitors come in a seemingly endless variety of shapes and sizes, and they can all

### R A _ + Figure 2: DC circuit to verify Ohm s Law. R is the resistor, A is the Ammeter, and V is the Voltmeter. A R _ +

Physics 221 Experiment 3: Simple DC Circuits and Resistors October 1, 2008 ntroduction n this experiment, we will investigate Ohm s Law, and study how resistors behave in various combinations. Along the

### Ohm s Law & Series Circuit

Open the TI-Nspire document Ohms_Law_&_Series_Circuit.tns. We all use and rely on electric circuits every day by flipping a switch, turning up the volume, or operating a computer or calculator. Even the

### Lab 3 Rectifier Circuits

ECET 242 Electronic Circuits Lab 3 Rectifier Circuits Page 1 of 5 Name: Objective: Students successfully completing this lab exercise will accomplish the following objectives: 1. Learn how to construct