OPTICS!
If a charge is accelerated at frequency f, it loses energy and momentum by creating photons, which carry away KE = hf, and momentum p = KE/c, where the constant h is 4.13 x 10-15 eV-sec and c is 3 x 108 m/s. Photons, like all bosons, are created from nothing, when the appropriate “coupling constant” is present. In the case of photons, the coupling constant is charge.

Roger Bacon (1214? - 1294) continued the work of Ibn al Haytham on optics and was the first person to do demonstrations of physical processes in the classroom.

In the 18th and 19th Centuries it was established beyond doubt that light behaved like a wave. In 1905 the fact that light actually consists of particles was demonstrated. In 1920, it was realized that any particle described by quantum physics, which has a definite energy and momentum, is described as a wave of probability, with frequency f = KE/h and wavelength λ = h/p. In drawing processes involving light, it is usually far easier to draw a ray, a line perpendicular everywhere to the advancing wavefronts, rather than to try to draw the wave itself.












Worked examples, light reflecting from plane mirror surfaces.

The corner reflector example, mentioned briefly in class.


A flat mirror forms a “virtual” image... the light seen comes from the surface of the mirror, NOT from the apparent position of the image.

When you look at yourself in a mirror, the image is totally different from what other people see, because although the overall image is rotated by 180o, left and right are not affected. Thus the image is, compared to the original, flopped left to right. To see yourself as you actually look to others, using mirrors, you would have to look at your image as reflected in the original mirror, using another mirror. The image in the second mirror will have left and right represented correctly, due to the second flop, which undoes the first.

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