When cooled below a certain critical temperature, some materials become perfect conductors. This phenomena is known as superconductivity and was first successfully described by Bardeen, Cooper and Schrieffer in 1957 (now known as BCS theory). Electrons form cooper pairs and undergo phonon interactions with the metallic lattice.
The slides outline superconductivity and the BCS theory.
These slides give an overview of metallic structure and conduction. The concept of a crystal lattice is also introduced, in addition to the method of x-ray diffraction (pioneered by William and William Bragg) which was used to determine the crystal structure of metals.
Before the widespread use of semiconductors, it was possible to compute data electronically using thermionic devices such as valves. These had a number of of functional inadequacies and were eventually superseded by the more compact and reliable solid state alternatives (transistors, diodes and integrated circuits).
The slides outline this progression, including the transition from germanium to silicon.
These slides provide an introduction to semiconductors, beginning with energy levels and the formation of energy bands in solid materials (conduction band, valance band). Conductors, insulators and semiconductors are compared in terms of their band structure. The effect of dopant atoms on the electrical properties of semiconductors is also mentioned (p-type, n-type).
Although Planck had suggested the quantisation of energy within black bodies, this concept had not been applied to all electromagnetic radiation until Einstein’s explanation of the photoelectric effect.
These slides provide an outline of the photoelectric effect, the classical difficulties surrounding its explanation and Einstein’s contribution.
One of the remaining problems in physics was the “ultraviolet catastrophe” – the predication that output radiation intensity would increase indefinitely at shorter wavelengths. This was in disagreement with both observation and the conservation of energy. Planck’s proposal of quantised energy levels within the black body provided some answer to this problem, and inadvertently began a new field of physics.
These slides outline the ultraviolet catastrophe and Planck’s contribution, including the relation E=hf.
In the late 1800’s, Hertz began experimenting with induction coils to verify Maxwell’s previous prediction of an electromagnetic spectrum. He discovered radio waves and measured their velocity to be very close to the speed of light.
These slides outline Hertz’s experiments and the quick application of radio waves into useful technology.