Charge to mass ratio of an electron was determined by Thomson . The chargeto mass ratio of an electron as 1.758820 x 10 11 C kg -1
Charge on an electron was determined by R A Millikan by using an oil dropexperiment . The value of the charge on an electron is -1.6 x 10 - 19 C .
The mass on an electron was determined by combining the results ofThomson ’ s experiment and Millikan ’ s oil drop experiment . The mass of anelectron was determined to be 9.1094 x 10 - 31 kg .
Discovery of protons and canal rays : Modified cathode ray tube experiment was carried out which led to the discovery of protons .
Characteristics of positively charged particles : a . Charge to mass ratio of particles depends on gas from which these originate
b . The positively charged particles depend upon the nature of gas present in the cathode ray discharge tube
c . Some of the positively charged particles carry a multiple of fundamental of electrical charge .
d . Behaviour of positively charged particles in electrical or magnetic field is opposite to that observed for cathode rays
Neutrons were discovered by James Chadwick by bombarding a thin sheet of beryllium by α- particles . They are electrically neutral particles having a mass slightly greater than that of the protons .