# 6/06 Ampere's Law. Ampere's Law. Andre-Marie Ampere in France felt that if a current in a wire exerted a magnetic

Save this PDF as:

Size: px
Start display at page:

Download "6/06 Ampere's Law. Ampere's Law. Andre-Marie Ampere in France felt that if a current in a wire exerted a magnetic"

## Transcription

1 About this lab: Ampere's Law Andre-Marie Ampere in France felt that if a current in a wire exerted a magnetic force on a compass needle, two such wires also should interact magnetically. Beginning within a year of Oersted's discovery, in a series of ingenious experiments he showed that this interaction was simple and fundamental --parallel (straight) currents attract, anti-parallel currents repel. The force between two long straight parallel currents was inversely proportional to the distance between them and proportional to the intensity of the current flowing in each. (See below on Ampere.) Today, we posit a magnetic field force intermediary, which is produced by currents (macroscopic or microscopic) and which, in turn, exerts force on other currents. The experimental properties of magnetic fields differ in a fundamental way from those found for electric fields the simplest magnetic field pattern is dipole, whereas the simplest electric field pattern is monopole (i.e., radial). The magnetic dipole is irreducible cutting a bar magnet does not produce separate + and magnetic monopoles, but rather two dipoles. Ampere's result for a long, straight current carrying wire implies a corresponding magnetic field which is concentric around the wire, proportional to the generating current and falling off inversely with distance. It is easy to see that the line integral along any one of these circles is proportional to the current within (2p r) * (1/r) remains constant, the sign depending on the current sign. It follows, with a little more work, that the line integral is not changed by path distortion. And, since the magnetic fields produced by several currents are the (vector) sum of those produced separately, the (algebraic) total current within a closed loop governs the line integral, independent of path. Apparatus: Solenoid and path integral board, DC power supply, cables, Hall Effect magnetic sensor, multimeter (two), meter stick, Graphical Analysis program References: Cutnell & Johnson: Physics, 6 th Ch. 21 Serway & Beichner: Physics for Scientists and Engineers, 5 th v2 Ch. 30

2 Figure 1 Magnetic field lines from two long straight parallel wires, carrying equal currents in opposite directions. B dl = 0 around the rectangle because there is no net current through the rectangular loop. But, for a loop encircling only one of the wires, B dl 0 From: mples.html

3 Figure 2 Magnetic field lines from two long straight parallel wires, carrying equal currents in opposite directions. B dl 0 because there is net current through the rectangular loop.

4 Figure 3 Magnetic field lines from a coil of N = 4 circular turns. A closed loop that passes through the coil will have B dl = 0 x 4I Tesla-meters, where I is the coil current in amperes. From A closed loop not passing through the loop will have B dl = 0. Introduction Ampere's Law states that the line integral of B and dl over a closed path is 0 current enclosed in that loop: times the B dl = 0 I enclosed µ 0 = 4π x 10-7 Tesla-meters/ampere For a long straight wire, the magnetic field is given by: B long straight wire = 0 I 2 R

5 (For a long straight wire carrying current I the B field line direction is tangent to centered circles. Along those circles, B is constant, so we can pull it out of the integral. The remaining integral is simply the circumference of the circle, which is 2 R, s o B long straight wire x ( 2 R )= 0 I. In your experiment, I must be understood as NI multimeter since each single coil wire of the solenoid contributes I to the enclosed current: B dl = 0 N I = 0 N I multimeter in general. Equation 1 where the dot denotes parallel component. If there is no net current within the closed path, the closed line integral is zero. This does not necessarily mean there is no B field present along the line integral, or no currents enclosed. Rather it means that the differential B dl elements sum to zero. Note that Up and down currents through the enclosed surface must be assigned opposite signs. Think of two adjacent wires with equal and opposite currents. The closed line integral surrounding them both is zero. If the closed line integral is not zero, you know that there is a net current within the closed path which is generating a magnetic field. In this lab you could actually sum up the contributions of B dl over such a path around a solenoid, to check if their sum does indeed equal 0 times the current enclosed by your path, if we knew the number N of solenoid turns (which we don't). Instead, you will assume the correctness of Ampere's Law and calculate N. The magnetic field around the solenoid will be determined by a magnetic sensor (which needs magnetic field calibration and voltage offset determination). You will measure the output voltage of the sensor (which is proportional to B after offset subtraction) using one multimeter. The current I through the solenoid will be measured directly by another multimeter.

6 Figure 4 Apparatus board with solenoid of (unknown) turns N, integration paths and calibration compass rose, power supplies and meters Some solenoid properties An application of Ampere s Law involves a solenoid (a wire coil wound on a cylinder) with: N = number of turns of solenoid (dimensionless) R = radius of coil (meters) I multimeter = current through solenoid (amperes) L = length of solenoid (meters). Point B field intensities are calculated to be: B C = 0 N I ammeter 4R 2 L 2 Equation 2 at the middle of the solenoid (on axis)

7 B E = 0 N I ammeter 2 R 2 L 2 Equation 3 at the end of the solenoid (on axis) N can thus be determined from these point values of B (since we can measure all other parameters), as well as from the line integral of tangential B along any loop passing through the coil. HALL EFFECT A magnetic field can be measured with a Hall Effect sensor. In the diagram below, a current, I, is transmitted through a silicon semiconductor. The potential between the top and bottom points is zero until a perpendicular magnetic field is applied which exerts a force on the moving charges. If the current consists of positive charged carriers, a positive charge will accumulate at the lower end of the conductor. Negative carrier flowing in the same direction as I will induce a negative charge at the lower end. Thus, the Hall Effect can distinguish the charge of the carrier! (In this figure, the convention that current is a flow of positive carriers is shown.) In any case, a small but measurable potential is induced by the magnetic field. If the field is reversed, so is the polarity of the induced voltage. Figure 5 Generation of a Hall voltage from a current flow in a magnetic field. Voltage sense depends on sign of charge carriers. You will use a Hall Effect magnetic field detector to measure the magnetic field. The detector is mounted at one end of a clear plastic block that can be oriented in a magnetic field. The output is amplified and recorded by a sensitive voltmeter. Evaluation of the line integral of the B-field s parallel components for two or more closed paths through a solenoid will determine the number of solenoid turns N, by application of Equation 1. In evaluation of the line integral we will approximate infinitesimal line elements dl by finite elements l :

8 0 N I ammeter = B dl B l = B l cos l for every contribution is simply the distance between the line segment markings. The angle in the dot product is always 0 degrees, since we are always orienting the black line along the path, so the above equation reduces to: 0 N I ammeter = B l This assumes that the loop passes through the solenoid, not around it. Do not reverse the direction of circulation around the loop during your summation. Keep magnetic material (steel watch bands, bracelets, etc.) away from the experiment. Besides the solenoid, currents in power supplies, computers, etc. produce magnetic fields Procedure SAVE GA FILES FREQUENTLY FOR CRASH RECOVERY Preliminary 1: Hall probe zero offset determination The Hall probe operation does not allow it to read zero for zero solenoid current. We need the zero current Hall probe reading value, V 0. We can turn off the solenoid current, but we can't turn off the earth's field, so we will measure V Hall for several solenoid currents I (+ and -), making the earth field contribution negligible, then plot and extrapolate V Hall readings to zero current to obtain the offset V Connect the red cable into the variable side of the power supply and turn the black knob fully counterclockwise (current is a minimum); this will allow a current to flow through the solenoid. Place the Hall sensor holder inside the center of the solenoid, oriented along the its length (9 o'clock compass direction). See figure below.

9 Figure 6 Finding the Hall voltage offset correction 2. Turn on the Keithley multimeter and set it to ammeter mode. This will enable you to measure the current through the solenoid. Keeping the Hall sensor fixed and motionless, measure V solenoid current as a function of current I as you increase the current from 0.04 A to 0.18A (approximate values). Reverse the power supply (variable side) leads. (Don't turn solenoid current supply off Hall probe voltage should remain on to maintain stabilization.) Record from A to A. B Open the Graphical Analysis program Ampere.GA3. Enter your data on Page 5 and observe the plot on page 6. Do a linear curve fit: V (solenoid current) = ax+b, then V 0 = b. Equation 4 b is V 0, the zero current value of Hall probe voltage ( zero offset correction). Preliminary 2: Magnetic Field Calibration of Hall Probe Voltage Calibrate the Hall sensor by using the Earth s magnetic field so that we can convert the Hall voltage (V-V 0 ) to a magnetic field (Tesla). Note that the Hall sensor measures the component of any magnetic field along the black line inscribed on the clear plastic sensor holder. It does not necessarily measure magnetic field- If you aim it

10 perpendicular to a strong magnetic field, it will give zero (after V 0 offset correction.) Since we do not know the direction of the horizontal field of the earth, the sensor will be rotated 360 degrees to determine the effective zero reading for the sensor. The sensor will register the highest voltage (magnetic field) when it is oriented towards the Earth's North Magnetic Pole and the lowest voltage (magnetic field) when it is pointed towards the Earth's South Magnetic Pole, which should be 180 degrees from North. At angles in between them the voltage will register some intermediate value, but never zero. The earth's field is a vector so the shape of V compass vs. compass angle θ should be sinusoidal V compass = A*sin(B*θ+C)+D The amplitude A (volts) of the compass curve sine fit yields a proportionality constant k in terms of the assumed horizontal component of the earth's field: k = B horizontal (Tesla)/Amplitude (volts), where B horizontal = 0.3x10-4 Tesla, in Piscataway. k = 0.3x10-4 /Amplitude Equation 5 The offset value D of the sinusoidal fit also determones V 0. We won't use this (the value you obtained previously is more accurate), but you could compare with the previous V 0 value. Enter V compass vs. angle (degrees) in the GA data columns on Page 5 and observe the graph on Page 6. Fit the sine and determine k from Equation 5. Enter your k and V 0 values in the three GA B calculated column definitions on Page 5 (for loops A, B and C), substituting for the placeholder values. Finally, after you enter your values, Graphical Analysis will calculate tangential B field components as B tangential = k (V Hall V 0 ). (This assumes that you orient the Hall probe correctly.) Field calibration in more detail: 1. Make sure the red cable is disconnected from the variable side of the power supply so that the solenoid has no current going through it. The regulated side of the power supply (5 V) powers the Hall sensor, which should always be on during the experiment

11 in order to maintain stability. Turn on the multimeter and set it to measure DC voltage - This will read the Hall sensor voltage which is related to magnetic field. Hall voltage readings should be zero before the power supply is turned on, since the power supply not only supplies the solenoid current; it also powers the Hall sensor. 2. Turn on the power supply. The Hall voltmeter should now register a voltage around 2.4 V. Place the Hall sensor, mounted on the clear plastic holder, on the ZERO FIELD COMPASS flat on the path integral board with the black cable. Rotate the holder and watch the voltage vary - which direction is Earth Magnetic North (golf course, ARC building, Physics Lecture Hall, Davidson)? 3. Take voltage data V compass as you rotate the sensor holder through 360 degrees, from 12 o'clock to 11 o'clock. See figures below. Fit a sine; calculate and record field calibration factor k as specified above (Equation 5). (The fit offset should be approximately your previously determined V 0 obtained by varying the solenoid current.) Figure 7 Mapping the earth's horizontal field component. C. Closed line integral enclosing non-zero net current (Loop B) Do this first.

12 Figure 8 Measuring a tangential magnetic field component Check the default dl values for each loop in the appropriate GA data columns on Page 5. If you plan on using different segment lengths, reset. Default values are set as 0.02 meters for loops B and C, and 0.01 meters for loop A, as marked on the solenoid board. Set the power supply so that it puts out ~ 0.15 A to the solenoid coil. Maintain this solenoid current for the remainder of the lab. Place the Hall sensor holder on Loop B, putting the tip (the sensor itself) right at the labeled starting point. Follow the path along the arrows indicated, taking voltage readings at each 1 or 2-centimeter line segment marking. Make sure the black line on the sensor holder is oriented along the path at every point. Enter your voltage data vs. Segment # in Ampere.GA3 ( Vb raw data ). Remember not to measure the start position twice. Examine the bar graph for Loop B. Use the Analyze-Integral function to sum up the B.dl contributions ( B dl B l ) and record. From Equation 1, calculate and record the number of turns N Loop B in the coil.

13 Figure 9 Entering parameters in a Graphical Analysis calculated column definition for Loop-A B-field tangential component. Remove and replace placeholder values of V 0 and k with your own values. D. Closed line integral enclosing zero net current (Loop C) Repeat above for Loop C (zero net current enclosed). Use same solenoid current. E. Comparison of end and center solenoid field strengths 1. Measure the length and radius (average) of the solenoid using the meter stick. Use mks units. 2. Measure axial values of the magnetic field, with the sensor holder oriented along the solenoid axis (lengthwise), at the center and at the end of the solenoid (these are clearly marked on the part of the path inside the solenoid). Record. Keep in mind that the sensor is at the tip of the sensor holder. 3. From each measurement, calculate N: N center and N end. Compare with N Loop B. F. Closed line integral enclosing zero net current (Loop A)

14 If time permits, repeat again, this time for Loop A (zero net current enclosed). Use same solenoid current as previously. Report You have all the data to plot and compare the line integral differentials for Loops A, B and C. You may view all of your line integral loop data simultaneously on Page 4. A bar graph would be confusing ; it is de-selected and point protectors substituted. Print a Page 1 bar graph for Loop B. Annotate it to explain relative signs and changes in terms of the path followed and of changes in Hall probe orientation. (Print additional graphs as directed.) On it, give your calibration parameter values of k (Tesla/volt) and V 0 (volts), your coil current I (amperes), your line integrals for loops A, B, C (Teslameters), line integral ratios C:B and A:B, your three values for N (solenoid turns): N Loop B, N center, N end. Give point B values (Tesla): B center and B end. Show any calculations on back. Look at the coil and estimate the # N of windings (estimate (number of layers) x (turns per layer). Is agreement w/ampere's Law reasonable? Record and discuss. Ampere and Electromagnetism Hans Christian Oersted was a professor of science at Copenhagen University. In 1820 he arranged in his home a science demonstration to friends and students. He planned to demonstrate the heating of a wire by an electric current, and also to carry out demonstrations of magnetism, for which he provided a compass needle mounted on a wooden stand. While performing his electric demonstration, Oersted noted to his surprise that every time the electric current was switched on, the compass needle moved. He kept quiet and finished the demonstrations, but in the months that followed worked hard trying to make sense out of the new phenomenon. But he couldn't! The needle was neither attracted to the wire nor repelled from it. Instead, it tended to stand at right angles.. In the end he published his findings (in Latin!) without any explanation.

15 Andre-Marie Ampere in France felt that if a current in a wire exerted a magnetic force on a compass needle, two such wires also should interact magnetically. Beginning within a year of Oersted's discovery, in a series of ingenious experiments he showed that this interaction was simple and fundamental --parallel (straight) currents attract, anti-parallel currents repel. The force between two long straight parallel currents was inversely proportional to the distance between them and proportional to the intensity of the current flowing in each. {Only for those pursuing the math: this is not the basic force formula. Given two short parallel currents I 1 and I 2, flowing in wire segements of length L 1 and L 1 and separated by a distance R, the basic formula gives the force between them as proportional to I 1 I 2 L 1 L 2 /R 2 ( It gets further complicated if the currents flow in directions inclined to each other by some angle). To find then the force between wires of complicated shape that carry electrical currents, all these little bitty contributions to the force must be added up, i.e. integrated.

16 For two straight wires, the final result is as above--a force inversely proportional to R, not to R 2.} There thus existed two kinds of forces associated with electricity--electric and magnetic. In 1864 James Clerk Maxwell demonstrated theoretically a subtle connection between the two types of force, unexpectedly involving the velocity of light. From this connection sprang the idea that light was an electric phenomenon, the discovery of radio waves, the theory of relativity and a great deal of present-day physics.

### Ampere's Law. Introduction. times the current enclosed in that loop: Ampere's Law states that the line integral of B and dl over a closed path is 0

1 Ampere's Law Purpose: To investigate Ampere's Law by measuring how magnetic field varies over a closed path; to examine how magnetic field depends upon current. Apparatus: Solenoid and path integral

### Chapter 14: Magnets and Electromagnetism

Chapter 14: Magnets and Electromagnetism 1. Electrons flow around a circular wire loop in a horizontal plane, in a direction that is clockwise when viewed from above. This causes a magnetic field. Inside

### Chapter 5. Magnetic Fields and Forces. 5.1 Introduction

Chapter 5 Magnetic Fields and Forces Helmholtz coils and a gaussmeter, two of the pieces of equipment that you will use in this experiment. 5.1 Introduction Just as stationary electric charges produce

### Physics 221 Experiment 5: Magnetic Fields

Physics 221 Experiment 5: Magnetic Fields August 25, 2007 ntroduction This experiment will examine the properties of magnetic fields. Magnetic fields can be created in a variety of ways, and are also found

### 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

### 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

### Magnetism. ***WARNING: Keep magnets away from computers and any computer disks!***

Magnetism This lab is a series of experiments investigating the properties of the magnetic field. First we will investigate the polarity of magnets and the shape of their field. Then we will explore the

### Chapter 19 Magnetism Magnets Poles of a magnet are the ends where objects are most strongly attracted Two poles, called north and south Like poles

Chapter 19 Magnetism Magnets Poles of a magnet are the ends where objects are most strongly attracted Two poles, called north and south Like poles repel each other and unlike poles attract each other Similar

### Magnetic Fields and Their Effects

Name Date Time to Complete h m Partner Course/ Section / Grade Magnetic Fields and Their Effects This experiment is intended to give you some hands-on experience with the effects of, and in some cases

### Magnetic Forces and Magnetic Fields

1 Magnets Magnets are metallic objects, mostly made out of iron, which attract other iron containing objects (nails) etc. Magnets orient themselves in roughly a north - south direction if they are allowed

### The purposes of this experiment are to test Faraday's Law qualitatively and to test Lenz's Law.

260 17-1 I. THEORY EXPERIMENT 17 QUALITATIVE STUDY OF INDUCED EMF Along the extended central axis of a bar magnet, the magnetic field vector B r, on the side nearer the North pole, points away from this

### Fall 12 PHY 122 Homework Solutions #8

Fall 12 PHY 122 Homework Solutions #8 Chapter 27 Problem 22 An electron moves with velocity v= (7.0i - 6.0j)10 4 m/s in a magnetic field B= (-0.80i + 0.60j)T. Determine the magnitude and direction of the

### CHARGE TO MASS RATIO OF THE ELECTRON

CHARGE TO MASS RATIO OF THE ELECTRON In solving many physics problems, it is necessary to use the value of one or more physical constants. Examples are the velocity of light, c, and mass of the electron,

### Chapter 19: Magnetic Forces and Fields

Chapter 19: Magnetic Forces and Fields Magnetic Fields Magnetic Force on a Point Charge Motion of a Charged Particle in a Magnetic Field Crossed E and B fields Magnetic Forces on Current Carrying Wires

### Lab 11: Magnetic Fields Name:

Lab 11: Magnetic Fields Name: Group Members: Date: TA s Name: Objectives: To measure and understand the magnetic field of a bar magnet. To measure and understand the magnetic field of an electromagnet,

### Magnetic Fields. I. Magnetic Field and Magnetic Field Lines

Magnetic Fields I. Magnetic Field and Magnetic Field Lines A. The concept of the magnetic field can be developed in a manner similar to the way we developed the electric field. The magnitude of the magnetic

### Magnetic Fields Lab. Station #1 à Determining Magnetic Flux Lines

Magnetic Fields Lab Regents Physics Name Mr. Putnam Station #1 à Determining Magnetic Flux Lines You must FIRST FIND WHICH END of your compass needle that points Geographic North. THIS WILL BE THE NORTH

### Chapter 27 Magnetic Field and Magnetic Forces

Chapter 27 Magnetic Field and Magnetic Forces - Magnetism - Magnetic Field - Magnetic Field Lines and Magnetic Flux - Motion of Charged Particles in a Magnetic Field - Applications of Motion of Charged

### 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

### Date: Deflection of an Electron in a Magnetic Field

Name: Partners: Date: Deflection of an Electron in a Magnetic Field Purpose In this lab, we use a Cathode Ray Tube (CRT) to measure the effects of an electric and magnetic field on the motion of a charged

### ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES

ELECTRIC FIELD LINES AND EQUIPOTENTIAL SURFACES The purpose of this lab session is to experimentally investigate the relation between electric field lines of force and equipotential surfaces in two dimensions.

### Lab 6: The Earth s Magnetic Field

ab 6: The Earth s Magnetic Field 1 Introduction Direction of the magnetic dipole moment m The earth just like other planetary bodies has a magnetic field. The purpose of this experiment is to measure the

### Physics 41, Winter 1998 Lab 1 - The Current Balance. Theory

Physics 41, Winter 1998 Lab 1 - The Current Balance Theory Consider a point at a perpendicular distance d from a long straight wire carrying a current I as shown in figure 1. If the wire is very long compared

### Magnetism. d. gives the direction of the force on a charge moving in a magnetic field. b. results in negative charges moving. clockwise.

Magnetism 1. An electron which moves with a speed of 3.0 10 4 m/s parallel to a uniform magnetic field of 0.40 T experiences a force of what magnitude? (e = 1.6 10 19 C) a. 4.8 10 14 N c. 2.2 10 24 N b.

### MAGNETIC EFFECTS OF ELECTRIC CURRENT

CHAPTER 13 MAGNETIC EFFECT OF ELECTRIC CURRENT In this chapter, we will study the effects of electric current : 1. Hans Christian Oersted (1777-1851) Oersted showed that electricity and magnetism are related

### Force on Moving Charges in a Magnetic Field

[ Assignment View ] [ Eðlisfræði 2, vor 2007 27. Magnetic Field and Magnetic Forces Assignment is due at 2:00am on Wednesday, February 28, 2007 Credit for problems submitted late will decrease to 0% after

### Objectives for the standardized exam

III. ELECTRICITY AND MAGNETISM A. Electrostatics 1. Charge and Coulomb s Law a) Students should understand the concept of electric charge, so they can: (1) Describe the types of charge and the attraction

### PHY 212 LAB Magnetic Field As a Function of Current

PHY 212 LAB Magnetic Field As a Function of Current Apparatus DC Power Supply two D batteries one round bulb and socket a long wire 10-Ω resistor set of alligator clilps coil Scotch tape function generator

### Eðlisfræði 2, vor 2007

[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 28. Sources of Magnetic Field Assignment is due at 2:00am on Wednesday, March 7, 2007 Credit for problems submitted late will decrease to 0% after the deadline

### 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

### The Magnetic Field in a Slinky

V mv The Magnetic Field in a Slinky Experiment 29 A solenoid is made by taking a tube and wrapping it with many turns of wire. A metal Slinky is the same shape and will serve as our solenoid. When a current

### LAB 8: Electron Charge-to-Mass Ratio

Name Date Partner(s) OBJECTIVES LAB 8: Electron Charge-to-Mass Ratio To understand how electric and magnetic fields impact an electron beam To experimentally determine the electron charge-to-mass ratio.

### Magnetic Field of a Circular Coil Lab 12

HB 11-26-07 Magnetic Field of a Circular Coil Lab 12 1 Magnetic Field of a Circular Coil Lab 12 Equipment- coil apparatus, BK Precision 2120B oscilloscope, Fluke multimeter, Wavetek FG3C function generator,

### Question Bank. 1. Electromagnetism 2. Magnetic Effects of an Electric Current 3. Electromagnetic Induction

1. Electromagnetism 2. Magnetic Effects of an Electric Current 3. Electromagnetic Induction 1. Diagram below shows a freely suspended magnetic needle. A copper wire is held parallel to the axis of magnetic

### Physics Notes for Class 12 Chapter 4 Moving Charges and Magnetrism

1 P a g e Physics Notes for Class 12 Chapter 4 Moving Charges and Magnetrism Oersted s Experiment A magnetic field is produced in the surrounding of any current carrying conductor. The direction of this

### Experiment 7: Forces and Torques on Magnetic Dipoles

MASSACHUSETTS INSTITUTE OF TECHNOLOY Department of Physics 8. Spring 5 OBJECTIVES Experiment 7: Forces and Torques on Magnetic Dipoles 1. To measure the magnetic fields due to a pair of current-carrying

### Experiment 9: Biot -Savart Law with Helmholtz Coil

Experiment 9: Biot -Savart Law with Helmholtz Coil ntroduction n this lab we will study the magnetic fields of circular current loops using the Biot-Savart law. The Biot-Savart Law states the magnetic

### Physics 12 Study Guide: Electromagnetism Magnetic Forces & Induction. Text References. 5 th Ed. Giancolli Pg

Objectives: Text References 5 th Ed. Giancolli Pg. 588-96 ELECTROMAGNETISM MAGNETIC FORCE AND FIELDS state the rules of magnetic interaction determine the direction of magnetic field lines use the right

### Charged Particles Moving in an Magnetic Field

rev 12/2016 Charged Particles Moving in an Magnetic Field Equipment for Part 1 Qty Item Parts Number 1 Magnetic Field Sensor CI-6520A 1 Zero Gauss Chamber EM-8652 1 Dip Needle SF-8619 1 Angle Indicator

### Lesson 3 DIRECT AND ALTERNATING CURRENTS. Task. The skills and knowledge taught in this lesson are common to all missile repairer tasks.

Lesson 3 DIRECT AND ALTERNATING CURRENTS Task. The skills and knowledge taught in this lesson are common to all missile repairer tasks. Objectives. When you have completed this lesson, you should be able

### Faraday's Law and Inductance

Page 1 of 8 test2labh_status.txt Use Internet Explorer for this laboratory. Save your work often. NADN ID: guest49 Section Number: guest All Team Members: Your Name: SP212 Lab: Faraday's Law and Inductance

### Chapter 22: Electric motors and electromagnetic induction

Chapter 22: Electric motors and electromagnetic induction The motor effect movement from electricity When a current is passed through a wire placed in a magnetic field a force is produced which acts on

### Module 3 : Electromagnetism Lecture 13 : Magnetic Field

Module 3 : Electromagnetism Lecture 13 : Magnetic Field Objectives In this lecture you will learn the following Electric current is the source of magnetic field. When a charged particle is placed in an

### 6/2016 E&M forces-1/8 ELECTRIC AND MAGNETIC FORCES. PURPOSE: To study the deflection of a beam of electrons by electric and magnetic fields.

6/016 E&M forces-1/8 ELECTRIC AND MAGNETIC FORCES PURPOSE: To study the deflection of a beam of electrons by electric and magnetic fields. APPARATUS: Electron beam tube, stand with coils, power supply,

### Experiment A5. Hysteresis in Magnetic Materials

HYSTERESIS IN MAGNETIC MATERIALS A5 1 Experiment A5. Hysteresis in Magnetic Materials Objectives This experiment illustrates energy losses in a transformer by using hysteresis curves. The difference betwen

### 1 of 7 4/13/2010 8:05 PM

Chapter 33 Homework Due: 8:00am on Wednesday, April 7, 2010 Note: To understand how points are awarded, read your instructor's Grading Policy [Return to Standard Assignment View] Canceling a Magnetic Field

### FORCE ON A CURRENT IN A MAGNETIC FIELD

7/16 Force current 1/8 FORCE ON A CURRENT IN A MAGNETIC FIELD PURPOSE: To study the force exerted on an electric current by a magnetic field. BACKGROUND: When an electric charge moves with a velocity v

### Chapter 22 Magnetism

22.6 Electric Current, Magnetic Fields, and Ampere s Law Chapter 22 Magnetism 22.1 The Magnetic Field 22.2 The Magnetic Force on Moving Charges 22.3 The Motion of Charged particles in a Magnetic Field

### Chapter 29. Magnetic Fields

Chapter 29 Magnetic Fields A Partial History of Magnetism 13 th century BC Chinese used a compass 800 BC Uses a magnetic needle Probably an invention of Arabic or Indian origin Greeks Discovered magnetite

### BASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS

BASIC ELECTRONICS PROF. T.S. NATARAJAN DEPT OF PHYSICS IIT MADRAS LECTURE-11 TRANSISTOR BIASING (Common Emitter Circuits, Fixed Bias, Collector to base Bias) Hello everybody! In our series of lectures

### Lab 9 Magnetic Interactions

Lab 9 Magnetic nteractions Physics 6 Lab What You Need To Know: The Physics Electricity and magnetism are intrinsically linked and not separate phenomena. Most of the electrical devices you will encounter

### Electromagnetic Induction - A

Electromagnetic Induction - A APPARATUS 1. Two 225-turn coils 2. Table Galvanometer 3. Rheostat 4. Iron and aluminum rods 5. Large circular loop mounted on board 6. AC ammeter 7. Variac 8. Search coil

### LABORATORY VI ELECTRICITY FROM MAGNETISM

LABORATORY VI ELECTRICITY FROM MAGNETISM In the previous problems you explored the magnetic field and its effect on moving charges. You also saw how magnetic fields could be created by electric currents.

### Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil

MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2006 Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil OBJECTIVES 1. To learn how to visualize magnetic field lines

### AP Physics C Chapter 23 Notes Yockers Faraday s Law, Inductance, and Maxwell s Equations

AP Physics C Chapter 3 Notes Yockers Faraday s aw, Inductance, and Maxwell s Equations Faraday s aw of Induction - induced current a metal wire moved in a uniform magnetic field - the charges (electrons)

### ANALYTICAL METHODS FOR ENGINEERS

UNIT 1: Unit code: QCF Level: 4 Credit value: 15 ANALYTICAL METHODS FOR ENGINEERS A/601/1401 OUTCOME - TRIGONOMETRIC METHODS TUTORIAL 1 SINUSOIDAL FUNCTION Be able to analyse and model engineering situations

### My lecture slides are posted at Information for Physics 112 midterm, Wednesday, May 2

My lecture slides are posted at http://www.physics.ohio-state.edu/~humanic/ Information for Physics 112 midterm, Wednesday, May 2 1) Format: 10 multiple choice questions (each worth 5 points) and two show-work

### Name: Date: Regents Physics Mr. Morgante UNIT 4B Magnetism

Name: Regents Physics Date: Mr. Morgante UNIT 4B Magnetism Magnetism -Magnetic Force exists b/w charges in motion. -Similar to electric fields, an X stands for a magnetic field line going into the page,

### Level 2 Physics: Demonstrate understanding of electricity and electromagnetism

Level 2 Physics: Demonstrate understanding of electricity and electromagnetism Static Electricity: Uniform electric field, electric field strength, force on a charge in an electric field, electric potential

### E/M Experiment: Electrons in a Magnetic Field.

E/M Experiment: Electrons in a Magnetic Field. PRE-LAB You will be doing this experiment before we cover the relevant material in class. But there are only two fundamental concepts that you need to understand.

### 1. Units of a magnetic field might be: A. C m/s B. C s/m C. C/kg D. kg/c s E. N/C m ans: D

Chapter 28: MAGNETIC FIELDS 1 Units of a magnetic field might be: A C m/s B C s/m C C/kg D kg/c s E N/C m 2 In the formula F = q v B: A F must be perpendicular to v but not necessarily to B B F must be

### Magnetic Field and Magnetic Forces

Chapter 27 Magnetic Field and Magnetic Forces PowerPoint Lectures for University Physics, Thirteenth Edition Hugh D. Young and Roger A. Freedman Lectures by Wayne Anderson Goals for Chapter 27 To study

### * Biot Savart s Law- Statement, Proof Applications of Biot Savart s Law * Magnetic Field Intensity H * Divergence of B * Curl of B. PPT No.

* Biot Savart s Law- Statement, Proof Applications of Biot Savart s Law * Magnetic Field Intensity H * Divergence of B * Curl of B PPT No. 17 Biot Savart s Law A straight infinitely long wire is carrying

### PSS 27.2 The Electric Field of a Continuous Distribution of Charge

Chapter 27 Solutions PSS 27.2 The Electric Field of a Continuous Distribution of Charge Description: Knight Problem-Solving Strategy 27.2 The Electric Field of a Continuous Distribution of Charge is illustrated.

### Electromagnetic Induction: Faraday's Law

1 Electromagnetic Induction: Faraday's Law OBJECTIVE: To understand how changing magnetic fields can produce electric currents. To examine Lenz's Law and the derivative form of Faraday's Law. EQUIPMENT:

### The DC Motor. Physics 1051 Laboratory #5 The DC Motor

The DC Motor Physics 1051 Laboratory #5 The DC Motor Contents Part I: Objective Part II: Introduction Magnetic Force Right Hand Rule Force on a Loop Magnetic Dipole Moment Torque Part II: Predictions Force

### Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil

MASSACHUSETTS INSTITUTE OF TECHNOLOGY Department of Physics 8.02 Spring 2009 Experiment 3: Magnetic Fields of a Bar Magnet and Helmholtz Coil OBJECTIVES 1. To learn how to visualize magnetic field lines

### Q28.1 A positive point charge is moving to the right. The magnetic field that the point charge produces at point P (see diagram below) P

Q28.1 A positive point charge is moving to the right. The magnetic field that the point charge produces at point P (see diagram below) P r + v r A. points in the same direction as v. B. points from point

### Force on a square loop of current in a uniform B-field.

Force on a square loop of current in a uniform B-field. F top = 0 θ = 0; sinθ = 0; so F B = 0 F bottom = 0 F left = I a B (out of page) F right = I a B (into page) Assume loop is on a frictionless axis

### Experiment 6: Magnetic Force on a Current Carrying Wire

Chapter 8 Experiment 6: Magnetic Force on a Current Carrying Wire 8.1 Introduction Maricourt (1269) is credited with some of the original work in magnetism. He identified the magnetic force centers of

### 5. Measurement of a magnetic field

H 5. Measurement of a magnetic field 5.1 Introduction Magnetic fields play an important role in physics and engineering. In this experiment, three different methods are examined for the measurement of

### PHY222 Lab 7 - Magnetic Fields and Right Hand Rules Magnetic forces on wires, electron beams, coils; direction of magnetic field in a coil

PHY222 Lab 7 - Magnetic Fields and Right Hand Rules Magnetic forces on wires, electron beams, coils; direction of magnetic field in a coil Print Your Name Print Your Partners' Names You will return this

### MAG Magnetic Fields revised July 24, 2012

MAG Magnetic Fields revised July 24, 2012 (You will do two experiments; this one (in Rock 402) and the Magnetic Induction experiment (in Rock 403). Sections will switch rooms and experiments half-way through

### 2. B The magnetic properties of a material depend on its. A) shape B) atomic structure C) position D) magnetic poles

ame: Magnetic Properties 1. B What happens if you break a magnet in half? A) One half will have a north pole only and one half will have a south pole only. B) Each half will be a new magnet, with both

### Electromagnetism Laws and Equations

Electromagnetism Laws and Equations Andrew McHutchon Michaelmas 203 Contents Electrostatics. Electric E- and D-fields............................................. Electrostatic Force............................................2

### Chapter 14 Magnets and Electromagnetism

Chapter 14 Magnets and Electromagnetism Magnets and Electromagnetism In the 19 th century experiments were done that showed that magnetic and electric effects were just different aspect of one fundamental

### 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

### 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

### Chapter 33. The Magnetic Field

Chapter 33. The Magnetic Field Digital information is stored on a hard disk as microscopic patches of magnetism. Just what is magnetism? How are magnetic fields created? What are their properties? These

### Chap 21. Electromagnetic Induction

Chap 21. Electromagnetic Induction Sec. 1 - Magnetic field Magnetic fields are produced by electric currents: They can be macroscopic currents in wires. They can be microscopic currents ex: with electrons

### Chapter 27 Magnetic Field an Magnetic Forces Study magnetic forces. Consider magnetic field and flux

Chapter 27 Magnetic Field an Magnetic Forces Study magnetic forces Consider magnetic field and flux Explore motion in a magnetic field Consider magnetic torque Apply magnetic principles and study the electric

### Teacher Content Brief

Teacher Content Brief Electric Motors Introduction Motors convert electric energy into mechanical energy. This mechanical energy turns the propellers on your Sea Perch. But what makes a motor spin? To

### Pearson Physics Level 30 Unit VI Forces and Fields: Chapter 12 Solutions

Concept Check (top) Pearson Physics Level 30 Unit VI Forces and Fields: Chapter 1 Solutions Student Book page 583 Concept Check (bottom) The north-seeking needle of a compass is attracted to what is called

### I d s r ˆ. However, this law can be difficult to use. If there. I total enclosed by. carrying wire using Ampere s Law B d s o

Physics 241 Lab: Solenoids http://bohr.physics.arizona.edu/~leone/ua/ua_spring_2010/phys241lab.html Name: Section 1: 1.1. A current carrying wire creates a magnetic field around the wire. This magnetic

### Magnetostatics (Free Space With Currents & Conductors)

Magnetostatics (Free Space With Currents & Conductors) Suggested Reading - Shen and Kong Ch. 13 Outline Review of Last Time: Gauss s Law Ampere s Law Applications of Ampere s Law Magnetostatic Boundary

### 33. Magnetic Field: Permanent Magnet

Name Period Date 33. Magnetic Field: Permanent Magnet Driving Question How do you think the strength of the magnetic field of a permanent magnet changes as you get farther away from the magnet. Background

### Magnetic Fields; Sources of Magnetic Field

This test covers magnetic fields, magnetic forces on charged particles and current-carrying wires, the Hall effect, the Biot-Savart Law, Ampère s Law, and the magnetic fields of current-carrying loops

### Moving Charge in Magnetic Field

Chapter 1 Moving Charge in Magnetic Field Day 1 Introduction Two bar magnets attract when opposite poles (N and S, or and N) are next to each other The bar magnets repel when like poles (N and N, or S

### Physics 30 Worksheet #10 : Magnetism From Electricity

Physics 30 Worksheet #10 : Magnetism From Electricity 1. Draw the magnetic field surrounding the wire showing electron current below. x 2. Draw the magnetic field surrounding the wire showing electron

### Multiple Choice Questions for Physics 1 BA113 Chapter 23 Electric Fields

Multiple Choice Questions for Physics 1 BA113 Chapter 23 Electric Fields 63 When a positive charge q is placed in the field created by two other charges Q 1 and Q 2, each a distance r away from q, the

### Magnets. We have all seen the demonstration where you put a magnet under a piece of glass, put some iron filings on top and see the effect.

Magnets We have all seen the demonstration where you put a magnet under a piece of glass, put some iron filings on top and see the effect. What you are seeing is another invisible force field known as

### Nowadays we know that magnetic fields are set up by charges in motion, as in

6 Magnetostatics 6.1 The magnetic field Although the phenomenon of magnetism was known about as early as the 13 th century BC, and used in compasses it was only in 1819 than Hans Oersted recognised that

### 5 Magnets and electromagnetism

Magnetism 5 Magnets and electromagnetism n our modern everyday life, the phenomenon of magnetism is associated with iron that is attracted by permanent magnets that can also be made of iron compounds.

### 2015 Pearson Education, Inc. Section 24.5 Magnetic Fields Exert Forces on Moving Charges

Section 24.5 Magnetic Fields Exert Forces on Moving Charges Magnetic Fields Sources of Magnetic Fields You already know that a moving charge is the creator of a magnetic field. Effects of Magnetic Fields

### Eðlisfræði 2, vor 2007

[ Assignment View ] [ Pri Eðlisfræði 2, vor 2007 29a. Electromagnetic Induction Assignment is due at 2:00am on Wednesday, March 7, 2007 Credit for problems submitted late will decrease to 0% after the

### Chapter 26 Magnetism

What is the fundamental hypothesis of science, the fundamental philosophy? [It is the following:] the sole test of the validity of any idea is experiment. Richard P. Feynman 26.1 The Force on a Charge

### Lecture PowerPoints. Chapter 20 Physics: Principles with Applications, 7 th edition Giancoli

Lecture PowerPoints Chapter 20 Physics: Principles with Applications, 7 th edition Giancoli This work is protected by United States copyright laws and is provided solely for the use of instructors in teaching

### 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