How much detail should we know on these dot points (mod 7) (1 Viewer)

[v.tex]

investigate Maxwell’s contribution to the classical theory of electromagnetism, including:


– unification of electricity and magnetism


– prediction of electromagnetic waves


– prediction of velocity (ACSPH113)


Physics Stage 6 Syllabus 59


● describe the production and propagation of electromagnetic waves and relate these processes


qualitatively to the predictions made by Maxwell’s electromagnetic theory (ACSPH112,


ACSPH113)


● conduct investigations of historical and contemporary methods used to determine the speed of


light and its current relationship to the measurement of time and distance (ACSPH082)



I swear the info that comes with these dot points, mostly the historical experiments measuring the speed of light are so confusing. Should we know many experiments, most of them i barley understand how they work.

 

[wizzkids]

The question about methods of measuring the speed of light is covered very well in most elementary text books. Basically you are looking at light "chopper" experiments conducted over very long baselines. You break a stream of light into very short pulses with a precisely known time period, and measure their time of flight.
Now, this is a very broad question about Maxwell's contribution to Physics.
You should know Maxwell was actually a gifted mathematician, and he did no experiments of his own. He became a Professor of Mathematics at Aberdeen (Scotland) at the comparatively young age of 25. In 1871 he became Professor of Experimental Physics at Cambridge University. He died from cancer in 1879 at the age of 49.
His contribution was to gather and systematise all the discoveries of other scientists and make them mathematically consistent.
Over a period of 9 years from 1864 to 1873 he worked through all the mysteries about electricity and magnetism, and constructed a new model of the electric and magnetic fields based largely on the model of Faraday of lines of magnetic flux.
Maxwell's model assumed there was a fluid that carried charge and an electromagnetic ether that could carry disturbances in the of lines flux (today we have abandoned the charged fluid and electromagnetic ether theories).
Maxwell was able to show that the electric and magnetic fields were not different stuff, they were manifestations of the electromagnetic field, the electric and magnetic fields were unified. Where one was changing it would force the other to change. He wrote this down in the form of 20 differential equations (it was left to another mathematical genius named Oliver Heaviside to tidy-up Maxwell's equations and reduce them to the four elegant differential equations that we now call Maxwell's Field Equations).
Maxwell was able to predict that a disturbance to the electromagnetic flux such as accelerating charges would radiate energy in all directions in the form of an electromagnetic wave in the ether. He hypothesised that there should be an entire spectrum of these electromagnetic waves but he had no way of proving his hypothesis.
He was able to predict mathematically from experimental constants the speed of propagation of these waves, which turned out to be remarkably similar to the speed of light. He reasoned that this could not be a coincidence.
Maxwell was able to correct Ampere's Law. He showed through a symmetry argument that it was incomplete, and he was shown to be correct.