Kiwanga, C. A. (2010)
In this module you will learn about an important topic in physics, namely Atomic Physics. The subject matter of the module is a principal component of the so called Modern Physics, a scientific discipline that came into being in the late 19th century and early 20th century. You will be guided through the historical development of atomic theories, through the work of Dalton, Thompson, Rutherford and Bohr. These four scientists have a very special place in the development of Atomic Physics. The work by Dalton and Thompson laid the ground on which Rutherford and Bohr built upon to the extent that the models developed by the latter two scientists are usable to some extent today. Hence you will be required to solve problems relating to Rutherford’s and Bohr’s models of the atom. In Learning Activity 2 of this module you will be guided through the gas discharge phenomenon and the onset of cathode rays. This phenomenon was a puzzle to the scientists of the day but led to an important discovery of the electron, the first sub- atomic particle to be discovered. Towards the end of the Learning Activity you will be guided through Millikan’s oil drop experiment that led to the discovery that electric charge is particulate or quantized. In Learning Activity 3, you will be guided through the evolution of atomic spectra and learn about the uniqueness of an atomic spectrum for every element. The uniqueness of atomic spectra has scientific and technological implications. In Learning Activity 4, you will be guided through the origin of x-rays, the development of x-ray spectra and the uniqueness of x-ray spectrum for every element. Towards the end of the unit we discuss and solve problems using Moseley’s law and finally you will learn about the use of x-rays as an analytical tool.
African Virtual University (AVU)