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 directly using a variant of the millikan oil drop experiment while the mass will be deduced from a measurement of the charge to mass ratio, e/m, combined with the charge measurement.
Measuring separately the electric charge (\(e\)) and the rest mass (\(m\)) of an electron is a difficult task because both quantities are extremely small (\(e\) = 160217733×10-19 coulombs, \(m\) = 91093897×10-31 kilograms) fortunately, the ratio of these two fundamental constants can be determined easily and precisely from the radius of curvature of an electron beam traveling in a known magnetic field. The determination of the charge to mass ratio of the electron a magnetic field produced by helmholz coils is used to deflect electrons into circular paths whose radii are known by knowing the energy of the electrons and the magnetic field strength, the ratio of the charge to mass (e/m) of the electron is determined. The time required to reach a detector at a known distance is measured and is a function of the mass-to-charge ratio of the particle (heavier particles attain lower speeds) the time and known experimental parameters provide the mass-to-charge ratio of the ion.
The charge to mass ratio of electron is e/m is the ratio between the charge of the electron by the mass of the electron which is 1758820 × 10^11 c/kg charge to mass ratio of electron was found out using the jj thomson experiment.
Exp1: charge to mass ratio of the electron both the charge and the mass of the electron are fundamental constant of considerable im-portance however, since the force on a charged particle moving in an electric or magnetic ﬁeld. In 1897, the mass-to-charge ratio of the electron was first measured by j j thomson by doing this, he showed that the electron was in fact a particle with a mass and a charge, and that its mass-to-charge ratio was much smaller than that of the hydrogen ion h . The ratio of the ions’ mass to charge, as long as their kinetic energy is the same thus, a magnetic field can be used to separate a monoenergetic ion beam into its various mass components a magnetic field will also exert a focusing action on a monoenergetic beam of ions.
Fortunately, the ratio of these two fundamental constants can be determined easily and precisely from the radius of curvature of an electron beam traveling in a known magnetic field an electron beam of a specified energy, and therefore a specified speed, may be produced conveniently in an \(e/m\) apparatus.