# CHARGE TO MASS RATIO OF THE ELECTRON

Save this PDF as:

Size: px
Start display at page:

## Transcription

1 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, m e. Fundamental physical constants are universal since their values are believed to be the same regardless of the time or place in the Universe. Some constants can be measured individually, but usually experiments yield only the values of combinations; for example e/m e, e/hc, or m e c 2. The individual values are obtained by equating and canceling among the combinations. In this experiment, you will measure the combination e/m e. The technique involves the motion of charged particles in a magnetic field. It should be noted that the value for e/m e is very precisely known: ( ± ) x coulomb/kg. The magnetic field used in this lab is far less precisely known, nevertheless, you should be able to obtain the first few decimal places. MOTION OF A CHARGED PARTICLE IN A MAGNETIC FIELD A charged particle moving in a magnetic field experiences a force known as the Lorentz force, which in vector notation is given by F = qv B (1) where q is the charge on the particle, v is the vector velocity, and B is the vector magnetic field. This vector cross product equation is a shorthand way of saying the following: (a) The force is perpendicular to both the velocity of the particle v and the direction of the magnetic field B. The direction of the force on a positive charge is given by a right-hand rule: F is in the direction of your thumb if the fingers of your right hand curl from v to B through the smaller angle. F is into the page in the sketch below if the charge is positive and out of the page if the charge is negative. v Particle Path θ B Magnetic Field (b) The magnitude of the force varies as the sine of the angle, θ, between the direction of motion and the direction of the field. (c) The magnitude of the force is proportional to q, v, and B. Hence, F = qvb sinθ (2)

2 A corollary of the above is that the magnetic field cannot speed up or slow down a charged particle because the force is always perpendicular to its direction of motion. The Lorentz force will only cause the particle's path to curve. With this in mind, you should be able to convince yourself of the following: (a) If the particle has its velocity vector parallel to the magnetic field direction, it will move in a straight line unaffected by the field. This is useful for finding the direction of a magnetic field. (b) If the particle is launched perpendicular to the field direction, it will move in a circle with the Lorentz force at a maximum. (c) If the particle is launched in any other direction, its path will be a helix. In measuring the charge to mass ratio e/m e in this experiment, the apparatus is arranged so that the force will be perpendicular to v and B. Then the charged particle will move in a curved path in a plane perpendicular to B. The velocity will change direction but not magnitude. In this case θ = 90 and from Equation (2) F = qvb (3) Recall from mechanics that a mass which experiences a constant force perpendicular to its velocity will move in a circle such that the force is directed toward its center. From Newton's Second Law for uniform circular motion F radial = mv 2 R (4) where R is the radius of the circular motion. In the situation where the only net force is the Lorentz force given by Equation (3), qvb = mv 2 R. (5) This expression can be simplified to give the charge to mass ratio as q m = v RB (6) In the case of the electron, q = e and m = mass of the electron, m e. Thus, the objective of this experiment is to produce electrons of known velocity v moving in a known magnetic field, B, and to measure the radius, R, of their circular motion. METHOD The apparatus consists of a cathode ray tube (CRT) mounted between a set of Helmholtz coils which produce the magnetic field. The CRT contains an electron gun which shoots out a stream of electrons along the axis of the CRT as shown in Figure 1. The

3 electrons are accelerated inside the gun by a potential difference, V, which is applied to the CRT by a power supply. The kinetic energy, 1 / 2 m e v 2, gained by an electron (charge = e) passing through a potential difference, V, is equal to ev. Hence, ev = 1 2 m e v 2 or v 2 = 2Ve m e (7) The stream of electrons passes a phosphorescent screen which makes a luminous line along the path of the electrons. The magnetic field of the Helmholtz coils is perpendicular to the screen and causes the path of the electrons to be an arc of a circle. The (x,y) grid markings on the screen are used to determine the radius of the electron path. Cathode Ray Tube A=(0,0) y x E Electron Beam B = (x,y) R R B is into page O Figure 1. Schematic of Cathode Ray Tube (CRT). Refer to Figure 1 to follow the geometry used to convert (x,y) values along the electron s path into its radius. Assume the electron enters the magnetic field at point A with coordinates (0,0) and exits at point B with coordinates (x,y). From the figure, the length of line OE = R -y and the length of line EB = x. Hence for the right triangle OEB, R 2 = x 2 + (R - y) 2 which reduces to R = x 2 2y + y 2 (8)

4 Combining Equations (6), (7) and (8) yields e m = 2 V e B 2 x 2 2 y + y 2 2 (9) where B is the magnetic field of the Helmholtz coils, e and m e are the electron s charge and mass, V is the potential applied to the CRT, and (x,y) are selected coordinates of the electron s path on the CRT grid. In SI units, B will be in tesla, x and y in meters, and V in volts. A schematic of the Helmholtz coil geometry is shown in Figure 2. As current passes through the Helmholtz coils, a magnetic field is generated. The field in a region near the center is uniform if the separation of the coils is equal to half of their diameter. Such an arrangement is named after its inventor, Helmholtz. Although the magnetic field strength decreases with distance along the axis from one coil, the sum of the fields from the two coils is nearly constant in the region between them. Variation in the field off the axis may produce some error (perhaps 10-30%) in your results. The magnetic field in tesla at the center of these particular Helmholtz coils is given by B = I (10) where I is current through the coils in amperes. For an electron path measured near the center of the coils, this value is sufficiently accurate. The magnetic field strength can be changed by adjusting the current passing through the coils. The magnetic field direction can be reversed by reversing the direction of the current. Experimental Zone Magnetic Field B d 2 d Figure 2. The Helmholtz Geometry (end view of coils).

5 APPARATUS Helmholtz coils e/m tube High voltage power supply 35V power supply DPDT switch Multimeter PROCEDURE 1. Examine your apparatus and check the Helmholtz geometry. Are the coils aligned parallel with each other? Do they have the correct separation, i.e. 1/2 the coil diameter? If not, loosen the plastic knobs at the coil bases, align, and re-tighten the knobs to hold coils in position. 2. Connect the Helmholtz coils, ammeter, current direction switch, and the TEL 800 power supply (select dc) as shown in Figure 3. Be sure the switch is wired as shown. Since you want the current in both coils to be in the same direction, make sure that the A and Z connections are wired properly. The Keithley multimeter (not power supply) should be used as the ammeter in this circuit to obtain accurate current readings. Digital Multimeter A Helmholtz Coils Low Voltage Power Supply AC + A Z V A A Z Direction Switch Figure 3. Wiring Diagram for Helmholtz Coils 3. Connect the CRT and TEL 813 high voltage power supply as shown in Figure 4. The 6.3 V connection provides the heat required for electron emission from the tube filament. Be sure to use a high voltage wire (white) in connecting the (+) HV terminal to the CRT. Do not use the Center Tap (CT) terminal. The two ( ) terminals (-HV and -6.3 V) of the TEL 813 power supply should be connected together and to the ( ) side of the CRT

6 filament. In applying high voltage to the CRT, always start low and increase slowly until the electron beam becomes visible. Watch the meter on the supply and do not exceed 3.5 kv or you may damage the CRT. Keep the high voltage set at minimum except when making measurements. Filament Voltage High Voltage High Voltage Power Supply { { V ac - V dc + HV Wire +HV HV CRT Figure 4. CRT-Power Supply Connections. 4. Have the T.F. check your circuit wiring before proceeding. Turn on the TEL 813 high voltage supply and increase the voltage (CRT potential, V) until the electron beam is visible. The Helmholtz coils should be off for now. Is the beam exactly horizontal? Why or why not? If there is some magnetic field causing a deviation, what is its approximate direction relative to the electron beam direction? Make a sketch. Do not change the orientation of the CRT on the lab table from this point onward. 5. You will need to compensate for any deviation of the beam from horizontal by taking two measurements with the Helmholtz coil magnetic field reversed. Turn on the TEL 800 power supply connected to the Helmholtz coils. Increase the current in the coils until the electron beam passes exactly through a convenient point (x,y) on the CRT grid. A coordinate around (10, 2) works well, but you may find a different point more convenient. Record the CRT potential, V; the current in the Helmholtz coils, I, measured with the Keithley meter; and your selected (x,y) coordinate. Now change the direction of the current in the Helmholtz coils and thus the magnetic field direction by reversing the current direction switch. Do not change the CRT potential. Does the electron beam pass exactly through the corresponding point, e.g. (x,-y), on the opposite half of the grid? If not adjust the current until it does. Record this current. Use the average of your 2 currents above for the determination of the Helmholtz coil magnetic field given in Equation Change the CRT potential (without exceeding 3.5 kv). Adjust the Helmholtz coil current until the electron beam passes exactly through the same (x,y) point used above. Record the current, CRT potential, and (x,y). Now reverse the current and use the same procedure as in Step 5 to determine the average current for use in Equation (10) for the magnetic field. Make additional measurements until you have values for 5 different CRT potentials.

7 7. For a given CRT potential (e.g., 2.0 kv), adjust the Helmholtz coil current so that the electron beam passes through some (x,y) point. Vary the current until you have 4 or more values for (x,y). Reverse the current direction as before for each of your (x,y) values. For each case, calculate the average current and the corresponding values of the magnetic field. Make a plot of B vs. 1/R. ANALYSIS AND QUESTIONS Use your data to calculate the values of the electron path radius, R; the magnetic field strength, B; and the electron charge to mass ratio, e/m e. Fill in the table on the data sheet. Determine your average value for e/m e and compare it to the accepted value. How well did you do? Discuss the possible sources of systematic error in your measurement of e/m e. Does reversing the current and averaging the values compensate for the effect of the Earth s magnetic field? Refer to your sketch from Step 4 and make a diagram to explain. Assume the Earth s field is constant. Make a plot of B vs. 1/R from the data obtained in Step 7 above. What is the functional dependence of the curve? What does it represent? If the electron s velocity were relativistic, (> 10 8 m/s), the equations derived for this experiment would not be valid. Using the highest CRT potential that you used, calculate the electron s velocity from Equation 7. Is it relativistic? How would you arrange the CRT and Helmholtz coils to cause the electron beam to undergo a helical (or spiral) motion? Draw a sketch of your proposed arrangement showing the directions of v, B, and F.

8 DATA SHEET e/me TA [ ] NAME: INSTRUCTOR: PARTNER: SECTION: DATE: Data for a fixed (x,y) or (x,-y) location: x = y = R = CRT Potential Coil Reversed Average Magnetic Field e/m e Average value for e/m e = Data for a fixed CRT Potential: V = Coil Reversed Average x y R Magnetic Field e/m e Average value for e/m e = Make plots and sketches on separate pages.

### 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.

### The Charge to Mass Ratio (e/m) Ratio of the Electron. NOTE: You will make several sketches of magnetic fields during the lab.

The Charge to Mass Ratio (e/m) Ratio of the Electron NOTE: You will make several sketches of magnetic fields during the lab. Remember to include these sketches in your lab notebook as they will be part

### 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.

### Modern Physics Laboratory e/m with Teltron Deflection Tube

Modern Physics Laboratory e/m with Teltron Deflection Tube Josh Diamond & John Cummings Fall 2010 Abstract The deflection of an electron beam by electric and magnetic fields is observed, and the charge

### Physics 19. Charge to Mass Ratio of the Electron

Physics 19 Charge to Mass Ratio of the Electron Revised 9/2012, ABG Theory Elementary particle physics has as its goal to know the properties of the many atomic and subatomic particles (mesons, quarks,

### 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

### qv x B FORCE: ELECTRONS IN A MAGNETIC FIELD

qv x B Force 9-1 qv x B FORCE: ELECTRONS IN A MAGNETIC FIELD Objectives: To see the effect of a magnetic field on a moving charge directly. To also measure the specific charge of electrons i.e. the ratio

### Measurement of Charge-to-Mass (e/m) Ratio for the Electron

Measurement of Charge-to-Mass (e/m) Ratio for the Electron Experiment objectives: measure the ratio of the electron charge-to-mass ratio e/m by studying the electron trajectories in a uniform magnetic

### Lab 5 - Electron Charge-to-Mass Ratio

Lab 5 Electron Charge-to-Mass Ratio L5-1 Name Date Partners Lab 5 - Electron Charge-to-Mass Ratio OBJECTIVES To understand how electric and magnetic fields impact an electron beam To experimentally determine

### 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,

### J. J. Thomson's Measurement of e/m for the electron

Physics 165 Laboratory J. J. Thomson's Measurement of e/m for the electron In 1897, the cathode ray tube or CRT, which is now a part of most TV sets, was the last word in advanced laboratory instrumentation

### EXPERIMENT IV. FORCE ON A MOVING CHARGE IN A MAGNETIC FIELD (e/m OF ELECTRON ) AND. FORCE ON A CURRENT CARRYING CONDUCTOR IN A MAGNETIC FIELD (µ o )

1 PRINCETON UNIVERSITY PHYSICS 104 LAB Physics Department Week #4 EXPERIMENT IV FORCE ON A MOVING CHARGE IN A MAGNETIC FIELD (e/m OF ELECTRON ) AND FORCE ON A CURRENT CARRYING CONDUCTOR IN A MAGNETIC FIELD

### 4.1.Motion Of Charged Particles In Electric And Magnetic Field Motion Of Charged Particles In An Electric Field

4.1.Motion Of Charged Particles In Electric And Magnetic Field 4.1.1. Motion Of Charged Particles In An Electric Field A charged particle in an electric field will experience an electric force due to the

### THE MAGNETIC FIELD. 9. Magnetism 1

THE MAGNETIC FIELD Magnets always have two poles: north and south Opposite poles attract, like poles repel If a bar magnet is suspended from a string so that it is free to rotate in the horizontal plane,

### Charge to mass ratio of the electron

1. Introduction Charge to mass ratio of the electron Julia Velkovska September 2006 In this lab you will repeat a classic experiment which was first performed by J.J. Thomson at the end of the 19 th century.

### 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

### SPH4U UNIVERSITY PHYSICS

SPH4U UNIVERSITY PHYSICS GRAVITATIONAL, ELECTRIC, &... FIELDS L Magnetic Force on Moving Charges (P.386-391) Particle Accelerators As was stated earlier, the ability to accelerate charged particles with

### Study the effects of electric and magnetic fields on a charged particle and measure the charge-to-mass ratio (e/m) of the electron.

Experiment 2 The Ratio e/m for Electrons 2.1 Objective Study the effects of electric and magnetic fields on a charged particle and measure the charge-to-mass ratio (e/m) of the electron. 2.2 Theory In

### MAGNETISM LAB: The Charge-to-Mass Ratio of the Electron

Physics 9 Charge-to-mass: e/m p. 1 NAME: SECTION NUMBER: TA: LAB PARTNERS: MAGNETISM LAB: The Charge-to-Mass Ratio of the Electron Introduction In this lab you will explore the motion of a charged particle

### 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

### Lab 4: Magnetic Force on Electrons

Lab 4: Magnetic Force on Electrons Introduction: Forces on particles are not limited to gravity and electricity. Magnetic forces also exist. This magnetic force is known as the Lorentz force and it is

### 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

### 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

### 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

### 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

### Motion of Charges in Combined Electric and Magnetic Fields; Measurement of the Ratio of the Electron Charge to the Electron Mass

Motion of Charges in Combined Electric and Magnetic Fields; Measurement of the Ratio of the Electron Charge to the Electron Mass Object: Understand the laws of force from electric and magnetic fields.

### 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

### 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

### 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

### Handout 7: Magnetic force. Magnetic force on moving charge

1 Handout 7: Magnetic force Magnetic force on moving charge A particle of charge q moving at velocity v in magnetic field B experiences a magnetic force F = qv B. The direction of the magnetic force is

### 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

### 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

### Electron Charge to Mass Ratio Matthew Norton, Chris Bush, Brian Atinaja, Becker Steven. Norton 0

Electron Charge to Mass Ratio Matthew Norton, Chris Bush, Brian Atinaja, Becker Steven Norton 0 Norton 1 Abstract The electron charge to mass ratio was an experiment that was used to calculate the ratio

### Chapter 21. Magnetic Forces and Magnetic Fields

Chapter 21 Magnetic Forces and Magnetic Fields 21.1 Magnetic Fields The needle of a compass is permanent magnet that has a north magnetic pole (N) at one end and a south magnetic pole (S) at the other.

### 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

### CHARGED PARTICLES & MAGNETIC FIELDS - WebAssign

Name: Period: Due Date: Lab Partners: CHARGED PARTICLES & MAGNETIC FIELDS - WebAssign Purpose: Use the CP program from Vernier to simulate the motion of charged particles in Magnetic and Electric Fields

### 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

### Electron Charge to Mass Ratio e/m

Electron Charge to Mass Ratio e/m J. Lukens, B. Reid, A. Tuggle PH 35-001, Group 4 18 January 010 Abstract We have repeated with some modifications an 1897 experiment by J. J. Thompson investigating the

### 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

### 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

### 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

### 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

### Magnetic Field Strength: Force on a Moving Charge in a Magnetic Field

Magnetic Field Strength: Force on a Moving Charge in a Magnetic Field Bởi: OpenStaxCollege What is the mechanism by which one magnet exerts a force on another? The answer is related to the fact that all

### 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

### Charge and Mass of the Electron

PHY 19 Charge and Mass of the Electron 1 Charge and Mass of the Electron Motivation for the Experiment The aim of this experiment is to measure the charge and mass of the electron. The charge will be measured

### 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,

### Deflection of Electrons in an Electric Field

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

### mv = ev ebr Application: circular motion of moving ions In a uniform magnetic field: The mass spectrometer KE=PE magnitude of electron charge

1.4 The Mass Spectrometer Application: circular motion of moving ions In a uniform magnetic field: The mass spectrometer mv r qb mv eb magnitude of electron charge 1 mv ev KEPE v 1 mv ebr m v e r m B m

### 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

### Section 9: Magnetic Forces on Moving Charges

Section 9: Magnetic Forces on Moving Charges In this lesson you will derive an expression for the magnetic force caused by a current carrying conductor on another current carrying conductor apply F = BIL

### Magnetic Fields ild and Forces

Magnetic Fields ild and Forces Physics 1 Facts about Magnetism Magnets have 2 poles (north and south) Like poles repel Unlike poles attract Magnets create a MAGNETIC FIELD around them Magnetic Field A

### 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

### Test - A2 Physics. Primary focus Magnetic Fields - Secondary focus electric fields (including circular motion and SHM elements)

Test - A2 Physics Primary focus Magnetic Fields - Secondary focus electric fields (including circular motion and SHM elements) Time allocation 40 minutes These questions were ALL taken from the June 2010

### 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

### Lesson 12: Magnetic Forces and Circular Motion!

Lesson 12: Magnetic Forces and Circular Motion If a magnet is placed in a magnetic field, it will experience a force. Types of magnets: Direction of the force on a permanent magnet: Direction of the force

### Module 3 : MAGNETIC FIELD Lecture 15 : Biot- Savarts' Law

Module 3 : MAGNETIC FIELD Lecture 15 : Biot- Savarts' Law Objectives In this lecture you will learn the following Study Biot-Savart's law Calculate magnetic field of induction due to some simple current

### Physics 2B. Lecture 29B

Physics 2B Lecture 29B "There is a magnet in your heart that will attract true friends. That magnet is unselfishness, thinking of others first. When you learn to live for others, they will live for you."

### PHYS 345 Laboratory: Charge to Mass Ratio of the Electron

PHYS 345 Laboratory: Charge to Mass Ratio of the Electron Purpose: Apparatus: To determine the charge to mass ratio of the electron and compare it with the accepted value. CENCO e/m apparatus (electron

### J.J. Thomson, Cathode Rays and the Electron

Introduction Voltage source Experimenters had noticed that sparks travel through rarefied (i.e. low pressure) air since the time of Franklin. The basic setup was to have two metal plates inside a glass

### Electron Diffraction

1. Introduction Electron Diffraction Julia Velkovska, Oct 2006 In this experiment you will explore the wave-particle duality. You will do so by observing electron diffraction. The goal will be to test

### Rotational Motion. Description of the motion. is the relation between ω and the speed at which the body travels along the circular path.

Rotational Motion We are now going to study one of the most common types of motion, that of a body constrained to move on a circular path. Description of the motion Let s first consider only the description

### EXPERIMENT #4 Charge to Mass ratio of the Electron

EXPERIMENT #4 Charge to Mass ratio of the Electron GOALS Physics Measure the charge-to-mass ratio e/m for electrons of a given kinetic energy moving in a magnetic field. Technique A low pressure Hg gas

### 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

### 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

### Pre-lab Quiz/PHYS 224 Magnetic Force and Current Balance. Your name Lab section

Pre-lab Quiz/PHYS 224 Magnetic Force and Current Balance Your name Lab section 1. What do you investigate in this lab? 2. Two straight wires are in parallel and carry electric currents in opposite directions

### Physics 104 Exam 2 Name

1. An electron moves with a velocity of 7.0 x 10 6 m/s due west in a uniform magnetic field of magnitude 4.0 T at an angle of 30 ast of orth. At the same point an electric field of magnitude 9.0 x 10 6

### HSC Physics SAMPLE LECTURE SLIDES

HSC SAMPLE LECTURE SLIDES HSC Exam Preparation Programs 4October2015 c 2015 Sci School TM.Allrightsreserved. Overview By the 1850 s vacuum pumps had become efficient enough to reduce the pressure inside

### Magnetic Forces cont.

Magnetic Fields Magnetism Magnets can exert forces on each other. The magnetic forces between north and south poles have the property that like poles repel each other, and unlike poles attract. This behavior

### 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

### Worked solutions Chapter 9 Magnets and electricity

9.1 Fundamentals of magnetism 1 A magnetic field exists at any point in space where a magnet or magnetic material (e.g. iron, nickel, cobalt) will experience a magnetic force. 2 C. The magnetic force between

### Chapter 20. Magnetic Forces and Magnetic Fields

Chapter 20 Magnetic Forces and Magnetic Fields The Motion of a Charged Particle in a Magnetic Field The circular trajectory. Since the magnetic force always remains perpendicular to the velocity, if a

### Homework #8 203-1-1721 Physics 2 for Students of Mechanical Engineering. Part A

Homework #8 203-1-1721 Physics 2 for Students of Mechanical Engineering Part A 1. Four particles follow the paths shown in Fig. 32-33 below as they pass through the magnetic field there. What can one conclude

### 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

### Magnetism Conceptual Questions. Name: Class: Date:

Name: Class: Date: Magnetism 22.1 Conceptual Questions 1) A proton, moving north, enters a magnetic field. Because of this field, the proton curves downward. We may conclude that the magnetic field must

### PHYS 155: Final Tutorial

Final Tutorial Saskatoon Engineering Students Society eric.peach@usask.ca April 13, 2015 Overview 1 2 3 4 5 6 7 Tutorial Slides These slides have been posted: sess.usask.ca homepage.usask.ca/esp991/ Section

### This Set o Slides - Day 20, Friday, Feb 19

This Set o Slides - Day 20, Friday, Feb 19 Magnetic Field of Moving Charge or Current Biot-Savart Law Cross Product. Biot-Savart Law as cross product. More right hand rules. Three total! Similar but different!

### Chapter 20. Magnetic Forces and Magnetic Fields

Chapter 20 Magnetic Forces and Magnetic Fields Magnetic Fields The most familiar example of magnetism for most people is a magnet. Every magnet has two poles, North and South --> called this since if the

### Electron Diffraction

Electron Diffraction Do moving electrons display wave nature? To answer this question you will direct a beam of electrons through a thin layer of carbon and analyze the resulting pattern. Theory Louis

### MAGNETIC FORCE ON AN ELECTRIC CHARGE

DO PHYSICS ONLINE MOTORS AND GENERATORS MAGNETIC ORCE ON AN ELECTRIC CHARGE Experiments show that moing electric charges are deflected in magnetic fields. Hence, moing electric charges experience forces

### Conceptual: 1, 3, 5, 6, 8, 16, 18, 19. Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65. Conceptual Questions

Conceptual: 1, 3, 5, 6, 8, 16, 18, 19 Problems: 4, 6, 8, 11, 16, 20, 23, 27, 34, 41, 45, 56, 60, 65 Conceptual Questions 1. The magnetic field cannot be described as the magnetic force per unit charge

### 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.

### MOVING CHARGES AND MAGNETISM

MOVING CHARGES AND MAGNETISM 1. A circular Coil of 50 turns and radius 0.2m carries of current of 12A Find (a). magnetic field at the centre of the coil and (b) magnetic moment associated with it. 3 scores

### Concept Review. Physics 1

Concept Review Physics 1 Speed and Velocity Speed is a measure of how much distance is covered divided by the time it takes. Sometimes it is referred to as the rate of motion. Common units for speed or

### 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

### HW 7 Q 14,20,20,23 P 3,4,8,6,8. Chapter 7. Rotational Motion of the Object. Dr. Armen Kocharian

HW 7 Q 14,20,20,23 P 3,4,8,6,8 Chapter 7 Rotational Motion of the Object Dr. Armen Kocharian Axis of Rotation The radian is a unit of angular measure The radian can be defined as the arc length s along

### 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

### 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

### 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.

### 5.Magnetic Fields due to Currents( with Answers)

5.Magnetic Fields due to Currents( with Answers) 1. Suitable units for µ. Ans: TmA -1 ( Recall magnetic field inside a solenoid is B= µ ni. B is in tesla, n in number of turn per metre, I is current in

### 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 Magnets

### 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

### ConcepTest PowerPoints

ConcepTest PowerPoints Chapter 20 Physics: Principles with Applications, 6 th edition Giancoli 2005 Pearson Prentice Hall This work is protected by United States copyright laws and is provided solely for

### Experiment #8: Magnetic Forces

Experiment #8: Magnetic Forces Purpose: To study the nature of magnetic forces exerted on currents. Equipment: Magnet Assembly and Stand Set of Current Loop PC oards Triple-Arm Pan alance 0 15 V dc Variable

### 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

### 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

### 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

### Chapter 19 Magnetism. National High Magnetic Field Laboratory Tallahassee, Florida. Maglev Train

Maglev Train Chapter 19 Magnetism Magnetic ield Electric Current and Magnetic field orce on an Electric Current in a Magnetic ield orce on an Moving Electric Charge in a Magnetic ield More than 30 magnets

### 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