Experiment 6 the chargetomass ratio of the electron ucla. The electron chargetomass ratio equipment the experiment and. Experiment q1 electron chargetomass ratio abstract the ratio em for electrons is determined by measuring the radius of curvature of the path followed by electrons of known velocity as they move in a known magnetic field. A beam of electrons was used that was subjected to a magnetic field that caused it to shift direction. Thomsons experiment and the chargetomass ratio of the electron. A particle of mass m and charge e moving in a magnetic induction field b will. Chargetomass ratio for the electron u of t physics. Charge to mass ratio of the electron vanderbilt university. Describe or make a rough sketch of the path of an electron traveling into a region with a constant bfield. Chargetomass ratio of the electron october 30, 2015 name. The magnetic field generated by a single loop charged particle in constant magnetic field.
Thompson discovered the first elementary particle, the electron, by measuring the ratio of its charge to mass in a manner similar to the experiment that we will. Motivation and history of the first em measurement consequences thomsons experiment the physics behind the experiment. The quantity representing the ratio of an electrons charge to its mass was experimentally sought after for the first time by j. Notice that there are two sheets tabs for this file at bottom. Simulation of thomsons experiment to measure the charge to mass ratio of an electron, with calculations. Experiment 6 the chargetomass ratio of the electron. Simulation of thomsons experiment to find charge to mass. The masstocharge ratio mq is a physical quantity that is most widely used in the electrodynamics of charged particles, e. They are same in charge and have the same physical properti. Chapter 1 measurement of chargetomass em ratio for the electron experiment objectives. Charge and mass of the electron michigan state university. Specific charge of the electron em related topics cathode rays, lorentz force, electron in crossed fields, electron mass, electron charge.
Fortunately, the ratio of these two fundamental constants can be determined easily and precisely from the radius of. If a uniform magnetic field b is perpendicular to the initial direction of motion of an electron beam, the electrons will be deflected by a force that is always. Chapter 1 measurement of chargetomass em ratio for the. Charge to mass ratio of the electron ryerson university. J j thomsons experiment to determine the charge to mass ratio of an electron. This experiment was one of the first experiments to attempt to. This experiment investigates the path of an electron in a magnetic field. Determination of the specific charge of the electron em from the path of an electron beam. Wesley odom, leif peterson, joshua williams, elena gregg phd the department of engineering oral roberts university introduction theory experimental setup results conclusion the charge tomass ratio of an electron was measured using a method similar to. Name the 2 forces that are equated in order to derive the charge to mass ratio relationship. Combine your results from steps 6 and 9 to write a formula which relates the radius of the electrons path rto. Lets imagine, we have the nucleus of protium and deuterium. In this experiment you will be measuring the charge to mass ratio, em, of the electron.
Determining the charge to mass ratio of the electron. The value of the ratio of the absolute value of the charge to mass em is computed from the relationships between the measured accelerating potential difference, v, the magnetic field, b, and the radius of the circular path which the electron beam describes, r. Use this physical model to design an experiment to measure the charge to mass ratio of an electron as well as the. The electron charge to mass ratio was an experiment that was used to calculate the ratio of the electrons charge to its mass. Charge to mass ratio of an electron new york university. Electron charge and mass quantity symbol value units mass me 9. His experimental apparatus is not very di erent from the one which you will use in this lab, and he was later awarded the nobel prize for his discovery.
Thomsons 1897 experiment in which he discovered the electron. Ratio of charge to mass em for the electron in this experiment we observe the motion of free electrons in a vacuum tube. Introduction and theory around the turn o f the century, two dramatic experiments established the existence of the electron, a charged particle that is very much smaller than an atom in size and in mass. Electron chargetomass ratio name partners prelab you are required to finish this section before coming to lab. Lab 5 electron chargetomass ratio l53 if one uses two coaxial coils of radius r that are a distance d apart, as shown in figure 5. Thomson had found a charged particle that had a specific. The magnetic force on an electron is given by f ev b. Ratio of mass to charge for an electron ksu physics kansas. References reese, university physics, brookscole, 2000. Simulation of jj thomsons experiment to find the charge to mass ratio of an electron. The first part of the experiment required varying circular helium electron paths with a constant accelerating voltage of 280 v.
Now focus on the motion of the electron in the magnetic eld. So people mistook the positive particle produced in the experiments to be protons exclusively. Joseph john thomson performed an experiment, in which he successfully. Thus in the nonrelativistic approximation, ev 1 2 mv2 3 combining eqs. It appears in the scientific fields of electron microscopy, cathode ray tubes, accelerator physics, nuclear physics, auger electron spectroscopy, cosmology and mass spectrometry. We will then determine the electron s charge to mass ratio em experimentally and compare it to theoretical calculations using equation 8. In this experiment, you will measure em, the ratio of the electrons charge e to its mass m. Quantities which are directly measurable in this lab are the accelerating voltage v, radius of the electrons path r, and the magnetic eld b. In this experiment you will use the relative positions of the emission lines of hydrogen and deuterium to the protonelectron mass ratio. Given that it is also possible to perform a measurement of e alone the millikan oil drop experiment, it is possible to obtain the value of the mass of the electron, a very.
Charge to mass ratio of electron new york university. In measuring the charge to mass ratio eme in this experiment, the apparatus is arranged. Experiment q1 electron chargetomass ratio abstract. Physua 72 intro to exp physics ii charge to mass ratio of electron from left to right in fig. The charge to mass ratio em for the electron introduction in 1897 j. Students will observe the interaction between a magnetic field and an electron beam, and measure the charge to mass ratio of the electron. Measuring separately the electric charge \e\ and the rest mass \m\ of an electron is a difficult task because both quantities are extremely small \e\ 1. Measurement of chargetomass em ratio for the electron experiment objectives. Hydrogendetermine e simplest of atomic, th systems, has an emission spectrum which is consistent with an elementary theory derived from. The charge to mass ratio of the electron 1 introduction in this exercise we will measure the charge to mass ratio of the electron by accelerating an electron beam through a known potential and measuring the radius of curvature of the beam in a known magnetic. Introduction in this lab you will repeat a classic experiment which was first performed by j. He conducted a series of revolutionary experiments with cathode ray tubes. Charge to mass ratio of electron was found out using the jj thomson experiment. In this experiment, the electron originates from the cathode with a negligible initial velocity.
Charge to mass ratio of an electron 2 theory let the mass, charge, radius, velocity, and acceleration of an electron be given by m, e, r, v, and v2rrespectively. Why is the charge of the mass ratio of an electron the. Charge to mass ratio of electron ohio wesleyan university. 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.
From their response to electric and magnetic fields the ratio of charge to mass for the electron can be determined. By measuring the deflection that a magnetic field produces on a beam of electrons having a known energy, you will deduce a value for the charge to mass ratio of electrons. The setup consists of an evacuated except for a low pressure of he gas cathode ray tube which produces a beam of electrons of variable energy. The he apparatus consists of an electron gun, a helium filled vacuum tube.
It is known that a current running through a solenoid creates a. The first is the experiment of joseph john thomson, who first demonstrated that atoms are actually composed of aggregates of charged particles. In this experiment, you will perform a modification of thomsons original work. Thomson first determined the specific charge charge to mass ratio em of the electron in 1887. Lab 5 electron chargetomass ratio university of virginia. Are there experiments where the charge to mass ratio for protons have been determined in the same way as in thompsons experiments where he determined the charge to mass ratio of electron but with protons instead of electrons. Millikan 18681953 was able to measure the charge of the electron 1. Fundamental physics experiments charge to mass ratio of. 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, me. This lab consists of two parts using one electron gun. Thomsons experiment and the charge tomass ratio of the electron. The value of the ratio of charge to mass em is computed from the relationships between the measured accelerating potential difference, the magnetic flux density, and the diameter of the circular path which the electron beam describes. Now your problem is to find the mass difference between these two nucleus. In this experiment, electrons are \boiled o of a hot lament.
This is a variation of the original experiment carried out by j. The nominal value for the apparatus you will be using is 1. Given that it is also possible to perform a measurement of e alone the millikan oil drop experiment, it is possible to obtain the. Abstract the classen em experiment performed was intended to demonstrate how the charge to mass ratio of an electron can be determined by allowing a current run through an apparatus known as the helmholtz coil. Electron charge to mass ratio matthew norton, chris bush. Charge to mass ratio of the electron julia velkovska september 2006 1.
Measurement of chargetomass em ratio for the electron. The importance of the masstocharge ratio, according. The negative terminal of the 500 v supply, the positive terminal of. He is also credited with the discovery of the electron itself. Chargetomass ratio for the electron introduction this is a variation of the original experiment carried out by j. Initially when experiments were conducted to find out the ratio,neutrons were yet to be discovered.
Youre guided through the simulation and the calculations. In this experiment you will measure em, the ratio of charge e to mass m of the electron. As vis perpendicular to b by experimental design, in terms of. P31220 lab 1 charge to mass ratio of the electron purpose. The specific charge of the electron is determined from the. They are the two notable isotopes of hydrogen atom. Physics 19 charge to mass ratio of the electron revised 92012, abg theory elementary particle physics has as its goal to know the properties of the many atomic and subatomic particles mesons, quarks, lambda particles, etc and to understand their place in nature.
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