The electromagnetic spectrum is very useful for diagnostic imaging of the human body. These slides outline the production and implementation of X-rays in imaging, including soft and hard X-rays as well as CAT scans. The practise of using visible light to image the body through the process of endoscopy is also introduced (including total internal reflection, coherent and incoherent fibre optic bundles).
These slides overview the medical physics option topic, and cover the first section on ultrasound. Concepts include acoustic impedance, reflection calculations, piezoelectric effect and a variety of scan processes (a-scan, b-scan, sector scan, phase scan).
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.
These slides provide an overview of the development of various discharge tubes (including maltese cross, paddle wheel, magnetic and electric deflection, decreasing pressures), and their application in determining the nature of cathode rays.
J.J Thompson’s experiment to determine the charge to mass ratio is outlined, in addition to striation patterns and modern applications of cathode ray tubes (oscilloscopes, televisions, computer monitors). The function of basic components in modern cathode ray tubes (electron gun, deflecting plates, fluorescent screen) is also given.
In the late 1800s, a small number of problems remained for physicists to solve, and a small number of observations remained unexplained. As solutions were developed to these problems, the fundamental understanding of physics was challenged and changed. Eventually new and useful technology was developed as a result of our improved understanding of physics.
These slides provide a brief comment on the context of ‘Ideas to Implementation’, revise electric fields and outline the behaviour of charged particles moving in a magnetic field.