Which particle is j. j. thomson credited with discovering
electron
neutron
proton
photon

Option (a) is the correct answer.

Explanation:

J.J. Thomson conducted the famous cathode ray experiment that led to the discovery of electrons.

A cathode ray tube consists of a vacuum glass tube with anode at one end and cathode at another end. The negatively charged conductor is called cathode whereas the positively charged conductor is called anode.

Electrons passing from cathode are attracted by the anode. Further, a small hole in anode allows some of the electrons to pass through it which results into beam of electrons. Adjacent to this hole, a plate with metal coating on it is places that glows when beam of electrons falls on it.

Thus, J. J. Thomson is credited with discovering electron.