Ernest Rutherford

  • Year:

    1910

  • Subject:

    Engineering

  • Award:

    Cresson

  • Citation:

    For distinguished work in electrical theory.

Ernest Rutherford was born in 1871, in Nelson, New Zealand. In 1889, Rutherford was awarded a scholarship and he proceeded to the University of New Zealand, Wellington. He graduated M.A. in 1893 with a double first in Mathematics and Physical Science and he continued with research work at the College for a short time, receiving the B.Sc. degree the following year. That same year, 1894, he was awarded an 1851 Exhibition Science Scholarship, enabling him to go to Trinity College, Cambridge, as a research student at the Cavendish Laboratory under J.J. Thomson. In 1897, he was awarded the B.A. Research Degree and the Coutts-Trotter Studentship of Trinity College.

In 1898, Rutherford departed for Canada when he took up the post of the Macdonald Chair of Physics at McGill University, Montreal. Rutherford returned to England in 1907 to become Langworthy Professor of Physics in the University of Manchester, and in 1919 he accepted an invitation to succeed Sir Joseph Thomson as Cavendish Professor of Physics at Cambridge.

While at the Cavendish Laboratory for the first time, Rutherford invented a detector for electromagnetic waves. He worked jointly with Thomson on the behaviour of the ions observed in gases which had been treated with X-rays, and also, in 1897, on the mobility of ions in relation to the strength of the electric field, and on related topics such as the photoelectric effect. In 1898, he reported the existence of alpha and beta rays in uranium radiation and indicated some of their properties.

In Montreal, he was able to continue his work on radioactive bodies, particularly on the emission of alpha rays. He studied the "emanation" of thorium and discovered a new noble gas, an isotope of radon, which was later to be known as thoron. Rutherford collaborated in creating the "disintegration theory" of radioactivity which regards radioactive phenomena as atomic--not molecular--processes. The theory was supported by a large amount of experimental evidence, a number of new radioactive substances were discovered and their position in the series of transformations was fixed.

At Manchester, Rutherford devised, in conjunction with H. Geiger, a method of detecting a single alpha particle and counting the number emitted from radium. In 1910, his investigations into the scattering of alpha rays and the nature of the inner structure of the atom which caused such scattering led to the postulation of his concept of the "nucleus," his greatest contribution to physics. According to him, practically the whole mass of the atom and at the same time all positive charge of the atom is concentrated in a minute space at the center. In 1912, Niels Bohr adapted Rutherford's nuclear structure to Max Planck's quantum theory and so obtained a theory of atomic structure which, with later improvements, remains valid to this day. In 1913, together with H. G. Moseley, he used cathode rays to bombard atoms of various elements and showed that the inner structures correspond with a group of lines which characterize the elements. Each element could then be assigned an atomic number and, more important, the properties of each element could be defined by this number. In 1919, during his last year at Manchester, he discovered that the nuclei of certain light elements, such as nitrogen, could be "disintegrated" by the impact of energetic alpha particles coming from some radioactive source, and that during this process fast protons were emitted. Blackett later proved, with the cloud chamber, that the nitrogen in this process was actually transformed into an oxygen isotope, so that Rutherford was the first to deliberately transmute one element into another.

Information as of 1910