Charge of Proton:
The charge of a proton is +1. It carries a positive electrical charge, which is equal in magnitude but opposite in sign to the charge of an electron. The charge of a proton is fundamental and cannot be further divided. It is one of the three fundamental subatomic particles that make up an atom, along with neutrons and electrons.

Charge of Electron:
The charge of an electron is -1. It carries a negative electrical charge, which is equal in magnitude but opposite in sign to the charge of a proton. Electrons are located outside the nucleus of an atom and are much smaller in mass compared to protons and neutrons. They orbit the nucleus in specific energy levels or shells.

Charge of Neutron:
The charge of a neutron is neutral. It carries no electrical charge and is considered electrically neutral. Neutrons are also present within the nucleus of an atom, alongside protons. They have a slightly larger mass compared to protons and electrons but do not have any net charge.

Discovery of Sub-atomic Particles: Electrons
The discovery of sub-atomic particles, particularly electrons, is credited to J.J. Thomson. In the late 19th century, Thomson conducted experiments using cathode ray tubes, which are vacuum tubes containing a stream of electrons. By applying electric and magnetic fields to these tubes, he observed the behavior of the cathode rays.

Thomson noticed that the cathode rays were deflected by electric and magnetic fields, indicating the presence of charged particles. He concluded that these particles were negatively charged and much lighter than atoms. Thomson proposed the "plum pudding" model of the atom, where electrons were embedded in a positively charged sphere.

This discovery of electrons revolutionized the understanding of atomic structure and led to the development of the modern atomic model. Thomson's work paved the way for further research and the discovery of other sub-atomic particles, such as protons and neutrons.

In summary, the charge of a proton is +1, the charge of an electron is -1, and the charge of a neutron is neutral. J.J. Thomson's experiments with cathode ray tubes led to the discovery of electrons and significantly contributed to our understanding of atomic structure.

Charge of electron is 1.9×10`-11