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

Save this PDF as:

Size: px
Start display at page:

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

## Transcription

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

2 Norton 1 Abstract The electron charge to mass ratio was an experiment that was used to calculate the ratio of the electron s charge to its mass. A beam of electrons was used that was subjected to a magnetic field that caused it to shift direction. This experiment was one of the first experiments to attempt to find the charge or mass of an electron. After the charge to mass ratio was found, all someone would have to do was to find the charge or mass of an electron, and the other value would be known. It was found that the electron charge to mass ratio when the voltage was held constant, was and when the current was held constant, the charge to mass ratio was Overall, the most accurate charge to mass ratio that was found was ± C/kg. Introduction When a particle with a charge q moves through a region that has a magnetic and an electric field, the force on the particle is given by, (1) where E is the electric fields and B is the magnetic field. In performing this experiment, an electron source, a heated tungsten filament and an electrode, and Helmholtz coils are used to create the magnetic field. The electron beam source and the electrode are in a container that has a small amount of mercury vapor. A near vacuum is necessary because if there were too many ions in the sealed vessel, they would be attracted to the positive and negative terminals and therefore neutralize the terminals. The gas in the sealed vessel is ionized and its electrons achieve an excited state. When these electrons return to their normal energy level, photons are released and thus, producing light. If the electron beam were to be in a complete vacuum, it would not be visible since it needs the other gas in the tube to become visible. Inside the container are five

3 Norton 2 pins that allow the diameter of the electron beam diameter. The values of the diameter of the pins are, 0.065, 0.078, 0.090, 0.103, and m. JJ The electron beam observed is a cathode rays. Cathode rays are streams of electrons that are observed in vacuum tubes. Thomson used cathode rays to find the wave-particle duality of light. JJ Thomson came to his conclusion about the wave-particle duality of cathode rays when he took two cylinders with a slit in them and put them inside of each other with the outer one grounded and the inner one attached to a measuring device. Thomson found that the cathode rays would not enter the slits unless a magnet acted upon them. Once the cathode rays entered the cylinders, a negative charge built up on the inner cylinder. Helmholz coils produce the magnetic field that is used to control the beam of electrons. Helmholtz coils have a mean radius, R and they are separated by a distance of R. A magnetic field is formed and it is given by, (2) which can be simplified to (3) where N is the number of turns in the coils, which is 72 for the setup that was used, and µ 0 is the permeability of free space, 4π 10-7 WB/A-m. Equation (3) is valid near the center of the coils. On the plane that is halfway between the coils with a small displacement in the z direction, the magnetic field is given by, (4)

4 Norton 3 where r is the distance from the z-axis. The magnetic field through the Helmholtz coils is shown in figure 1 1. Fig. 1. Magnetic field for Helmholtz coils In the center of the coils, there is a region that has a nearly uniform magnetic field in all directions. In order to find the equation that will allow for the calculation of e/m, one starts with the kinetic field of an electron that is accelerated through an electric potential, V, which is given by, (5) 1 Taken from

5 Norton 4 Where V is the anode potential and e is the charge of an electron. The equation's right-hand side is the familiar kinetic energy of a particle of mass, m, and speed, v. The scalar form of equation (1) is needed because there is no electric field Since the electron beam is traveling in a circle, one must also consider the centripetal force for an electron with a mass, m, following a circular path with a radius of r, with a speed of v. (6) (7) However, equations (6) and (7) are describing the same thing so (8) Equation (8) can be simplified to This equation contains the velocity v, which one can eliminate by using equation (5). By rewriting equation (5), one finds (9) (10) By substituting equation 10 into equation 9, and then by squaring both sides, one obtains (11) By simplifying equation (11), one achieves the desired result, the charge to mass ratio of the electron

6 Norton 5 (12) The accepted value for the charge to mass ratio is C/kg. Experimental Procedure Initially the direction of the earth s magnetic field, then the apparatus was aligned to the earth s north-south axis. The apparatus was then inclined an angle of 28º in an attempt to cancel the earths magnetic field so that it would have a negligible affect on the experiment. Each group member measured to the diameter of the Helmholtz coils. The mean diameter of the inner diameter was 0.644±0.005m and the mean diameter of the outer diameter was 0.678± In performing the calculations, the inner diameter was used because the inner diameter describes the distance that the coils were from the electron beam. The outer diameter was not used because it added over 0.03m onto the calculations and added 0.03m on the coils that did not contribute to the magnetic field. The measurement of the diameter was done using a one-meter stick that had an uncertainty of ±0.005m. The meter stick was held perpendicular the rings and the diameter was measured. The Helmholtz coils used in this experiment were not circular. The measurements of the diameter varied as much as 0.017m. Therefore, one must conclude that the Helmholtz rings used in the experiment were not circular. The distance between the Helmholtz coils was measured in a similar fashion. The mean inner distance was.0310m and the mean outer distance was 0.349± The inner distance was again used due to the reason stated before in why the inner diameter was used. The distance between the coils varied the same as the diameter of the coils did, 0.017m. The distance between the coils is approximately equal to the radius; however, there is enough variance in the measure

7 Norton 6 of the distance to create some doubt that the distance between the coils equaled the radius of the coils. Figure 2 is the circuit diagram for the Helmholtz ring, Figure 3 is the circuit diagram for the filament, and Figure 4 is the circuit diagram for the anode. Ring Ammeter Fig. 2. Circuit diagram for Helmholtz rings Filament Fig. 3. Circuit diagram for filament V Anode Fig. 4. Circuit diagram for anode

8 Norton 7 Notice that the circuits in figures 3 and 4 are both grounded; they are grounded to a common ground. The ground is needed to allow for accurate measurements in the anode and filament circuits, because otherwise it would not be possible to take useable measurements because there would be no common reference point between the circuits. When the coil current is varied, the beam of electrons starts out slightly more than 90º from the pins. Then as the current is increased, the beam of electrons curls in towards the pins and eventually intercepts each pin. When the anode voltage was varied, a similar behavior was noticed, however, it was not possible to make the electron beam intercept all the pins for higher amperages in the Helmholtz coils. When the direction of the current in the Helmholtz coils was reversed, the electron beam curled the opposite way. In an another attempt to find out how the electron beam was affected by the presence of a magnetic field, the electron beam was set such that it intersected the third pin. A bar magnet was used to affect the electron beam. It is possible to use a bar magnet to form a helix with the electron beam. If the north end of the magnet is on the underside of the apparatus, with the magnet held horizontal to the table, the north end of the magnet pulls the electron beam in while the south end of the magnet pulls it away, thus producing a helix. The apparatus was set to an anode voltage of 30V. The beam was not initially straight; therefore, the current through the coils was increased until the beam was straight. This current was recorded and then was subtracted from the values of the current at each pin to correct for the earth s magnetic field. The current is increased until it intercepts the outermost pin and then the other four pins. This procedure was repeated for voltages of 40, 50, and 60V. Table 1 shows the data for the twenty measurements of the potential.

9 Norton 8 V = 30.0 V = 40.1 I I I I I I I I I I I I V = 50.0 V = 60.0 I I I I I I I I I I I I Table 1. Data taken at fixed anode potential The experiment was then repeated with the current through the Helmholtz currents held constant and the voltage through the anode potential. This method is less reliable because the setup that was used did not allow the voltage to be increased to the point where the electron beam would intercept the inner pins, therefore, that data was not available to be used to calculate the electron charge to mass ratio. Table 2 shows this data Amp = 2.5 Amp = 3.0 V V 1 V V V V V V V V Amp = 3.5 Amp = 4.5 V 1 V 1 V 2 V 2 V 3 V 3 V V 4 V V Table 2. Data taken at fixed Helmholtz current

10 Norton 9 It is possible to determine the electron charge to mass ratio for each current and voltage value. Table 3 shows the data for the values for the charge to mass ratio for each measured value of voltage or amperage. 1.65E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E E+11 Table 3. Electron charge to mass ratio for each measurement made, each in C/kg Figure 5 shows a histogram of the results for the electron charge to mass ratio. Fig. 5. Histogram of electron charge to mass ratio The average value for electron charge to mass ratio was C/kg with a standard deviation of If the extraneous value, e/m= C/kg, is removed, the mean

11 Norton 10 electron charge to mass ratio is C/kg with a standard deviation of The percent difference between all the values and accepted value is 8.81% and the percent difference with the extraneous value removed is 6.16%. However, the values for the charge to mass ratio with constant current should be excluded from the calculations. Since the Helmholtz coils were not perfectly circular and the distance between the coils was not equal to the radius of the coils, the constant current through the Helmholtz coils did not produce the desired result. The Helmholtz coils were not set up correctly, therefore, the magnetic field created by the coils is not constant. When the voltage was held constant the current was changing and thus the magnetic field was changing, therefore, the changes in the magnetic field were cancelled out over many measurements. Since the assumption is made that the magnetic field is constant when calculating the charge to mass ration using the values for a constant current is false, the values for the charge to mass ratio calculated for those values should be ignored because they are based upon highly unreliable sources. If the values of charge to mass ratio are used with excluding the values for the constant current, the mean of the values is C/kg with a standard deviation of The percent difference between this value and the accepted value is 2.47%. Figure 6 shows the histogram for these values of the charge to mass ratio. Notice how the counts all together when the constant voltage data was used. There is no point that is off by itself that is a factor of ten off from the other ones. One should also consider the amount that the beam had to be offset to make it appear straight. This amount should be able to be found without measuring it. However, a graph of the data does not appear to give any information about I 0. Figure 7 shows the graph of each set of data versus the distance it is from the electron beam source.

12 Norton 11 Fig. 6. Histogram for electron charge to mass ratio for only the data from the constant current Figure 7. Current vs. 1 / distance from electron beam source

13 Norton 12 Notice that the y-intercept for a voltage of 30.0V is 0.20 and the measured value is This is the only y-intercept that is close to I 0 value. Therefore, there should be no correlation between the y-intercept and the I 0 values. The I 0 value is the correction for imperfections in the Helmholtz coils and the earth s magnetic field that was not cancelled out by tilting the apparatus. Another way to examine the problem is to look at the graph of the voltage versus the magnetic field multiplied by the pin distance, quantity squared. Figure 8 shows this graph. Fig. 8. Voltage vs. (Br) 2 Notice how one point is way off and does not fit the general trend. This skews the curve fit of the data. The slope of a linear least squares fit line on this graph, voltage over the magnetic filed multiplied by the pin distance, quantity squared. This is equal to one-half of electron charge to mass ratio, equation (13) shows this,

14 Norton 13 (13) The slope of the linear least square line of the graph is , which is almost half of what the value should be. However, in the earlier, there was one point that was off by a factor of ten from the other values. If this point is again removed from the calculations, a better fit was obtained. Figure 9 shows this graph. Fig. 9. Voltage vs. (Br) 2 with the erroneous point removed The value for the slop of this line is very close to the expected value of one-half of the electron charge to mass ratio, it was , which has a percent error of 7.51%. If one considers only the values from the constant current experiment again, the slope of the line is This has

15 Norton 14 a percent error of 1.13% also, if one were to consider more than the allowed significant digits, percent difference between the two percent errors is, of the order 10-4, which is beyond the ability of the significant digits that are required. Therefore, there is no difference between the values for the electron charge to mass ratio from the slop of the line are more reliable then calculating a value for the ratio for each value and then taking the mean of the values. This data helps to show that the calculated values for the electron charge to mass ratio are precise and can be considered accurate. There were several apparent systemic errors apparent in this experiment. It is difficult to account for all the factors that could have produced error in this experiment. There is the error that could have resulted from the earth s magnetic field. The earth s magnetic field may have affected the results from the experiment. There may have also been environmental factors involved with the experiment; it is unknown if the temperature of the room affected the electron beam or if the size of the Helmholtz coils varied slightly from changes in temperature. In addition, it is unknown if the angle that the apparatus was held at was held constant, it may have slipped slightly over the course of the experiment. There is also the parallax that occurred during the measurement of the diameter of the Helmholtz rings and the distance between them. While there were methods took to minimize the parallax errors, it is almost impossible to get rid of it completely. There was also some instrument drift, in this experiment; the value of the voltage would shift between two or three values. The current measured by the ammeter would also increase over time. There was also hysteresis when voltage or current was changed. There were uncertainties related to every step in the calculations of the electron charge to mass ratio. The uncertainty in the voltmeter was ±0.1V. The uncertainty of the ammeter was ±0.01 Amps. The uncertainty of the meter stick is technically ±0.0005m, but it was

16 Norton 15 considered±0.001m to account for any parallax in the measurements. After performing an uncertainty analysis, it was found that the electron charge to mass ratio is most accurately reported as ± C/kg. Conclusion This experiment was designed to discover the electron charge to mass ratio. This experiment was designed to allow for an analysis of the errors involved in performing an experiment. In performing this experiment, the best estimate of the electron charge to mass ratio was C/kg with a standard deviation of the best percent error obtained was 2.47%. However, slope of the best-fit line from equation (13) produced the estimate of the electron charge to mass ratio, C/kg, which has a percent error of 1.19%. This experiment could have been improved by redesigning the apparatus to allow it to follow designs more precisely. It was found that the Helmholtz coils were not circular in addition; the distance between the Helmholtz coils was not equal to the radius of the Helmholtz coils. Moreover, a lecture on the process of performing uncertainty calculations over many steps in a calculation. Answers to Questions 1.) The magnetic field from the apparatus varied from T to T. This is within an order of ten from the earth s magnetic field. Therefore, the earth s magnetic field, which is approximately T, is close enough that it could interfere with the experiment. However, several steps were taken to minimize its affects on the apparatus; however, the earth s magnetic field most likely had an affect, negligible as it may be, may have been a factor in the error in this experiment. 2.) Equation (3) uses the difference current because there must be a correction for the fact that the electron beam did not initially come straight out perpendicular the pins of the apparatus. If

17 Norton 16 this corrected value were not used, the calculated value for the electron charge to mass ratio would be a too small, and thus inaccurate. 3.) Since a no-zero y-intercept was observed in figure 7, there must be some improvements made to the experiment. The best way to facilitate this would be to redesign the apparatus to allow for the correct dimensions. In addition, there might have been greater measures taken cancel out the earth s magnetic field, such as increasing the inclination of the apparatus. 4.) The shape of the Helmholtz coils affected the experiment since they were not circular; the magnetic field was not uniform as it was expected to be. Therefore, the fact that the Helmholtz rings were more of an oval than a circle, the result of this experiment was slightly skewed. 5.) J.J. Thomson measured the charge-to-mass ratio of the cathode rays by measuring how much they were deflected by a magnetic field and how much energy they carried. He found that the charge to mass ratio was over a thousand times higher than that of a proton, suggesting either that the particles were very light or very highly charged. Thomson's conclusions were bold: cathode rays were indeed made of particles, which he called corpuscles, and these corpuscles came from within the atoms of the electrodes, themselves, meaning they were in fact divisible. Thomson imagined the atom as being made up of these corpuscles swarming in a sea of positive charge; this was his plum pudding model of the atom. Another attempt to find e/m can be done by Dunnington's Method, which involves the angular momentum and deflection due to a perpendicular magnetic field. In addition, The Magnetron Method- Using a GRD7 Valve (Ferranti valve), electrons are expelled from a hot tungsten wire filament towards an anode. The electron is then deflected using a solenoid. From the current in the solenoid and the current in the Ferranti Valve, e/m can be calculated. Another method is the fine beam Tube Method- Electrons are accelerated from a cathode to a cap shaped anode. The electron is then expelled into a helium

18 Norton 17 filled ray tube, producing a luminous circle. From the radius of this circle, e/m is calculated. Thomson measured v by using the Schuster's estimate. In addition, in a lecture, Wiechert stated that he tried to find the electron s velocity by comparing the time taken by the cathode rays to pass along the tube with the time of swing of an electrical oscillation of the Hertzian type. The apparatus used in the experiment is similar to Thompson s design, except for that it can be aligned with the earth s magnetic field to minimize its affects on the expect. Therefore, our apparatus is better than Thompson s design. 6.) I have not performed the Millikan oil drop experiment, however, the accepted value for the charge of an electron, C can be used to find the mass of the electron. which has a percent error of 1.10% of the theoretical value of kg?

### 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.

### 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.

### 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

### 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

### 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,

### 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

### 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

### 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

### 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

### 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

### 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.

### 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

### 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

### 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

### 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,

### 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.

### Review Questions PHYS 2426 Exam 2

Review Questions PHYS 2426 Exam 2 1. If 4.7 x 10 16 electrons pass a particular point in a wire every second, what is the current in the wire? A) 4.7 ma B) 7.5 A C) 2.9 A D) 7.5 ma E) 0.29 A Ans: D 2.

### 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

### 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. 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

### 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

### 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

### 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

### 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

### 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

### 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.

### 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

### 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

### 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

### 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

### Millikan Oil Drop Experiment Matthew Norton, Jurasits Christopher, Heyduck William, Nick Chumbley. Norton 0

Millikan Oil Drop Experiment Matthew Norton, Jurasits Christopher, Heyduck William, Nick Chumbley Norton 0 Norton 1 Abstract The charge of an electron can be experimentally measured by observing an oil

### 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

### 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,

### 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

### 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

### Physics 126 Practice Exam #3 Professor Siegel

Physics 126 Practice Exam #3 Professor Siegel Name: Lab Day: 1. Which one of the following statements concerning the magnetic force on a charged particle in a magnetic field is true? A) The magnetic force

### 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

### 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

### 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

### 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

### Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION ( )

a. Using Faraday s law: Experimental Question 1: Levitation of Conductors in an Oscillating Magnetic Field SOLUTION The overall sign will not be graded. For the current, we use the extensive hints in the

### Physics 112 Homework 5 (solutions) (2004 Fall) Solutions to Homework Questions 5

Solutions to Homework Questions 5 Chapt19, Problem-2: (a) Find the direction of the force on a proton (a positively charged particle) moving through the magnetic fields in Figure P19.2, as shown. (b) Repeat

### 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

### ** Can skip to Problems: 6, 7, 9, 15, 19, 28, 29, 35, 36, 39, 42 **

Walker, Physics, 3 rd Edition Chapter 22 ** Can skip to Problems: 6, 7, 9, 15, 19, 28, 29, 35, 36, 39, 42 ** Conceptual Questions (Answers to odd-numbered Conceptual Questions can be found in the back

### Physics 1653 Exam 3 - Review Questions

Physics 1653 Exam 3 - Review Questions 3.0 Two uncharged conducting spheres, A and B, are suspended from insulating threads so that they touch each other. While a negatively charged rod is held near, but

### Graphical Presentation of Data

Graphical Presentation of Data Guidelines for Making Graphs Titles should tell the reader exactly what is graphed Remove stray lines, legends, points, and any other unintended additions by the computer

### 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

### 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

### 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

### 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

### 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

### 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

### My Website:

PH203 Recitation Week 09 Problem Set Spring 2015 Ryan Scheirer Email: scheirer@onid.orst.edu My Website: http://people.oregonstate.edu/~scheirer/ph203_rec.html Problem 01 For the following questions, use

### 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

### Charged Particle in a Magnetic Field

Charged Particle in a Magnetic Field Consider a particle moving in an external magnetic field with its velocity perpendicular to the field The force is always directed toward the center of the circular

### 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

### 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

### 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

### 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

### A METHOD OF CALIBRATING HELMHOLTZ COILS FOR THE MEASUREMENT OF PERMANENT MAGNETS

A METHOD OF CALIBRATING HELMHOLTZ COILS FOR THE MEASUREMENT OF PERMANENT MAGNETS Joseph J. Stupak Jr, Oersted Technology Tualatin, Oregon (reprinted from IMCSD 24th Annual Proceedings 1995) ABSTRACT The

### 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

### People s Physics book

The Big Idea Quantum Mechanics, discovered early in the 20th century, completely shook the way physicists think. Quantum Mechanics is the description of how the universe works on the very small scale.

### Cathode Ray Tube. Introduction. Functional principle

Introduction The Cathode Ray Tube or Braun s Tube was invented by the German physicist Karl Ferdinand Braun in 897 and is today used in computer monitors, TV sets and oscilloscope tubes. The path of the

### 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

### 1.2 ERRORS AND UNCERTAINTIES Notes

1.2 ERRORS AND UNCERTAINTIES Notes I. UNCERTAINTY AND ERROR IN MEASUREMENT A. PRECISION AND ACCURACY B. RANDOM AND SYSTEMATIC ERRORS C. REPORTING A SINGLE MEASUREMENT D. REPORTING YOUR BEST ESTIMATE OF

### 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

### Lab 7: Rotational Motion

Lab 7: Rotational Motion Equipment: DataStudio, rotary motion sensor mounted on 80 cm rod and heavy duty bench clamp (PASCO ME-9472), string with loop at one end and small white bead at the other end (125

### 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 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

### Magnetic Fields and Forces. AP Physics B

Magnetic ields and orces AP Physics acts about Magnetism Magnets have 2 poles (north and south) Like poles repel Unlike poles attract Magnets create a MAGNETIC IELD around them Magnetic ield A bar magnet

### 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

### AP1 Oscillations. 1. Which of the following statements about a spring-block oscillator in simple harmonic motion about its equilibrium point is false?

1. Which of the following statements about a spring-block oscillator in simple harmonic motion about its equilibrium point is false? (A) The displacement is directly related to the acceleration. (B) The

### 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

### Radioactivity. PC1144 Physics IV. 1 Purpose. 2 Equipment. 3 Theory

PC1144 Physics IV Radioactivity 1 Purpose Investigate the analogy between the decay of dice nuclei and radioactive nuclei. Determine experimental and theoretical values of the decay constant λ and the

### Linear Centripetal Tangential speed acceleration acceleration A) Rω Rω 2 Rα B) Rω Rα Rω 2 C) Rω 2 Rα Rω D) Rω Rω 2 Rω E) Rω 2 Rα Rω 2 Ans: A

1. Two points, A and B, are on a disk that rotates about an axis. Point A is closer to the axis than point B. Which of the following is not true? A) Point B has the greater speed. B) Point A has the lesser

### How did scientists determine the structures that are inside an atom?

Chapter 4 Atomic Structure 4.1 Defining the Atom 4.2 Structure of the Nuclear Atom 4.3 Distinguishing Among Atoms 1 Copyright Pearson Education, Inc., or its affiliates. All Rights Reserved. CHEMISTRY

### 2.4 Early Experiments to Characterize the Atom

2.4 Early Experiments to Characterize the Atom Early Experiments to Characterize the Atom J. J. Thomson (1856-1940) - postulated the existence of negatively charged particles called electrons using cathode

### Calculate the centripetal acceleration of the boot just before impact

(ii) alculate the centripetal acceleration of the boot just before impact....... (iii) iscuss briefly the radial force on the knee joint before impact and during the impact................. (4) (Total

### 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

### 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

### A2 Physics Unit 7 Magnetic Fields. Mr D Powell

A Physics Unit 7 Magnetic Fields Mr D Powell Chapter Map Circumference circle = r Distance trav = ¼ * r WD = Fd = d*mv /r Sub in eq to give B B 7.1 Current-carrying conductors in a magnetic field Specification

### Physics 42 Lab 4 Fall 2012 Cathode Ray Tube (CRT)

Physics 42 Lab 4 Fall 202 Cathode Ray Tube (CRT) PRE-LAB Read the background information in the lab below and then derive this formula for the deflection. D = LPV defl 2 SV accel () Redraw the diagram

### physics 112N magnetic fields and forces

physics 112N magnetic fields and forces bar magnet & iron filings physics 112N 2 bar magnets physics 112N 3 the Earth s magnetic field physics 112N 4 electro -magnetism! is there a connection between electricity

### Lab 5: Conservation of Energy

Lab 5: Conservation of Energy Equipment SWS, 1-meter stick, 2-meter stick, heavy duty bench clamp, 90-cm rod, 40-cm rod, 2 double clamps, brass spring, 100-g mass, 500-g mass with 5-cm cardboard square

### The structure of atoms

The structure of atoms Atomic models The Rutherford experiment Bohr's theory of the hidrogen atom The Frank-Hertz experiment Atomic models arly ideas One of the most intriguing questions, to which already

### 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

### Chapter 19 Magnetic Forces and Fields

Chapter 19 Magnetic Forces and Fields Student: 3. The magnetism of the Earth acts approximately as if it originates from a huge bar magnet within the Earth. Which of the following statements are true?

### 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

### 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

### The History of the Atom

The History of the Atom Timeline: 400 BC Scientist: Democritus (Greek Philosopher) Democritus was a Greek philosopher who was the first person to use the term atom (atomos: meaning indivisible). atom.

### VELOCITY, ACCELERATION, FORCE

VELOCITY, ACCELERATION, FORCE velocity Velocity v is a vector, with units of meters per second ( m s ). Velocity indicates the rate of change of the object s position ( r ); i.e., velocity tells you how

### 1. Separation is easy with a magnet (try it and be amazed!).

EXERCISES 1. Separation is easy with a magnet (try it and be amazed!). 2. All magnetism originates in moving electric charges. For an electron there is magnetism associated with its spin about its own

### Physics Spring Experiment #8 1 Experiment #8, Magnetic Forces Using the Current Balance

Physics 182 - Spring 2012 - Experiment #8 1 Experiment #8, Magnetic Forces Using the Current Balance 1 Purpose 1. To demonstrate and measure the magnetic forces between current carrying wires. 2. To verify

### BASANT S SCIENCE ACADEMY STUDY MATERIAL MAGNETIC EFFECT OF CURRENT

BASANT S SCIENCE ACADEMY Why does a compass needle get deflected when brought near a bar magnet? A compass needle is a small bar magnet. When it is brought near a bar magnet, its magnetic field lines interact

### Angular velocity. Angular velocity measures how quickly the object is rotating. Average angular velocity. Instantaneous angular velocity

Angular velocity Angular velocity measures how quickly the object is rotating. Average angular velocity Instantaneous angular velocity Two coins rotate on a turntable. Coin B is twice as far from the axis

### Magnetic Force on a Current-Carrying Wire

Title: Original Version: Revision: Authors: Appropriate Level: Abstract: Time Required: NY Standards Met: AP Physics Learning Objective: Magnetic Force on a Current-Carrying Wire 11 November 2006 24 June

### 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

### 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