Charge to mass ratio, of electron

J. J. Thomson Plum pudding model charge-to-mass ratio of electron Work with cathode rays discovered the positive and negative nature of the atom also determined the charge-to-mass ratio for electrons... 

Figure 2.6 J. J. Thomson calculated the charge to mass ratio of electrons. He used results from experiments with electrons in cathode-ray tubes.

Thomson s momentous discovery of the electron 100 years ago this year is a story familiar to anyone who has enrolled in an undergraduate chemistry course. His experiments with cathode-ray tubes allowed him to determine the charge-to-mass ratio of the electron—with a mass some 1,000 times less than the smallest particle previously found—and to establish that it was a component of all matter. Thus Thomson earned a place in the annals of physics—and the honor of a centenary. We might also, however, take note of another contribution Thomson made, one that is not so widely known. 

The charge and mass of an electron are often denoted by the letters e and m, respectively. In 1897, J. J. Thomson calculated the e/m ratio for an electron, and for this he was awarded a Nobel prize in 1905. In this activity, you will follow in Thomson s footsteps and determine the charge to mass ratio of an electron. 

Walter Kanfmarm also reported the determination of the charge-to-mass ratio of cathode rays (abont 10 emu g- ) in a paper he submitted in April 1897 (7). Kanfmarm also based his result on magnetic deflection measurements however, he concluded that the hypothesis of cathode rays as emitted particles could not explain his data. (One of the outstanding questions in the study of cathode rays in the late 1890s was whether they were particles or electromagnetic waves. Thomson and Kanfmarm were typical of their coimtrymen most British researchers leaned toward the particulate hypothesis and most Germans toward waves.) Today Kanfmarm is better known for his careful measurements of the velocity-dependent mass of the electron published over several years beginning in 1901 these results were later explained by special relativity. 

The stationary sedimentation velocity of a particle is an experimentally accessible quantity for some systems, so item 4 summarizes much of our interest in sedimentation. Unfortunately, it is the ratio (m/f) rather than m alone that is obtained from sedimentation velocity in the general case of particles of unspecified geometry. The situation is comparable to the result of the classical experiment of J. J. Thomson in which the charge-to-mass ratio of the electron was determined. 

Anomalous electron moment correction Atomic mass unit Avogadro constant Bohr magneton Bohr radius Boltzmann constant Charge-to-mass ratio for electron Compton wavelength of electron... 

The determination of the g factor thus requires a measurement of the Larmor and the cyclotron frequency. The electrons cyclotron frequency may conveniently be replaced by w /u> x w, where uj, is the ions cyclotron frequency. This is of advantage because the cyclotron frequency of the ion and the Larmor precession frequency can measured at the same particle. The ratio ujec/ujlc is the charge to mass ratio of the ion to the electron. For the case of Carbon it has been determined in Penning trap experiments by van Dyck and coworkers [16],... 

Explain how J. J. Thomson s determination of the charge-to-mass ratio of the electron led to the conclusion that atoms were composed of subatomic particles. 

An a particle is the nucleus of a He atom, (a) How many protons and neutrons are in an a particle (b) What force holds the protons and neutrons together in the a particle (c) What is the charge on an a particle in rmits of electronic charge (d) The charge-to-mass ratio of an a particle is 4.8224 x 10 C/g. Based on the charge on the particle, calculate its mass in grams and in amu. (e) By using the data in Table 2.1, compare your answer for part (d) with the sum of the masses of the individual subatomic particles. Can you explain the difference in mass ... 

The effect of electric current on nanohber morphology investigated using a held emission scanning electron microscopy (EE-SEM). Charge-to-mass ratio of a highly conducting liquid on nanohber uniformity also studied. 

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