Unit 4: The Wave Nature Of Lightmr.'s Learning Website

Have you ever thought about how nature likes to arrange itself in patterns in order to act efficiently? Nothing in nature happens without a reason, all of these patterns have an important reason to exist and they also happen to be beautiful to watch. Check out examples of some of these patterns and you may be able to spot a few the next time you go for a walk.

A fractal is a detailed pattern that looks similar at any scale and repeats itself over time. A fractal's pattern gets more complex as you observe it at larger scales. This example of a fractal shows simple shapes multiplying over time, yet maintaining the same pattern. Examples of fractals in nature are snowflakes, trees branching, lightning, and ferns.

A spiral is a curved pattern that focuses on a center point and a series of circular shapes that revolve around it. Examples of spirals are pine cones, pineapples, hurricanes. The reason for why plants use a spiral form like the leaf picture above is because they are constantly trying to grow but stay secure. A spiral shape causes plants to condense themselves and not take up as much space, causing it to be stronger and more durable against the elements.

A Voronoi pattern provides clues to nature’s tendency to favor efficiency: the nearest neighbor, shortest path, and tightest fit. Each cell in a Voronoi pattern has a seed point. Everything inside a cell is closer to it than to any other seed. The lines between cells are always halfway between neighboring seeds. Other examples of Voronoi patterns are the skin of a giraffe, corn on the cob, honeycombs, foam bubbles, the cells in a leaf, and a head of garlic.

There is a quantum nature to the electric and magnetic fields in light (quantum theory of radiation). But most of the stuff you look at can be explained using a classical wave model of light and a. Light theory in the 19th century and beyond. In the face of this compelling evidence, nineteenth-century scientists had to concede that light was a wave. This happened slowly, though, hampered by Newton's reputation and the legacy of his corpuscular theory.Yet, once it did take root, the idea of light as a wave paved the way for the nineteenth-century Scottish physicist James Clerk Maxwell to. File on the right hand side for the above image if you need to zoom in. Wave Speed = Distance Covered/Time taken. Properties of Waves. The prime properties of waves are as follows: Amplitude – Wave is an energy transport phenomenon. Amplitude is the height of the wave, usually measured in meters. It is directly related to the amount of energy carried by a wave. Since waves always are moving, one more important term to describe a wave is the time it takes for one wavelength to pass a specific point in space. This term, referred to as the period, T, is equivalent to the wavelength, T = Period = 2π/k, however it is given in units of time (sec) rather than distance. Understanding the mathematics behind wave functions allows us to better.




Light is a transverse, electromagnetic wave that can be seen by the typical human. The wave nature of light was first illustrated through experiments on diffraction and interference. Like all electromagnetic waves, light can travel through a vacuum. The transverse nature of light can be demonstrated through polarization.

  • In 1678, Christiaan Huygens (1629–1695) published Traité de la Lumiere, where he argued in favor of the wave nature of light. Huygens stated that an expanding sphere of light behaves as if each point on the wave front were a new source of radiation of the same frequency and phase.
  • Thomas Young (1773–1829) and Augustin-Jean Fresnel (1788–1827) disproved Newton's corpuscular theory.


The diamond dimensions modpack modpack. Light is produced by one of two methods…

  • Incandescence is the emission of light from 'hot' matter (T ≳ 800 K).
  • Luminescence is the emission of light when excited electrons fall to lower energy levels
    (in matter that may or may not be 'hot').

Unit 4: The Wave Nature Of Lightmr.'s Learning Website Site


Just notes so far. The speed of light in a vacuum is represented by the letter c from the Latin celeritas — swiftness. Measurements of the speed of light.

Veramente non l'ho sperimentata, salvo che in lontananza piccola, cioè manco d'un miglio, dal che non ho potuto assicurarmi se veramente la comparsa del lume opposto sia instantanea; ma ben, se non instantanea, velocissima….In fact I have tried the experiment only at a short distance, less than a mile, from which I have not been able to ascertain with certainty whether the appearance of the opposite light was instantaneous or not; but if not instantaneous it is extraordinarily rapid….
Galileo Galilei, 1638Galileo Galilei, 1638

Ole Rømer (1644–1710) Denmark. 'Démonstration touchant le mouvement de la lumière trouvé par M. Roemer de l'Académie des Sciences.' Journal des Scavans. 7 December 1676. Rømer's idea was to use the transits of Jupiter's moon Io to determine the time. Not local time, which was already possible, but a 'universal' time that would be the same for all observers on the Earth, Knowing the standard time would allow one to determine one's longitude on the Earth — a handy thing to know when navigating the featureless oceans.

Unfortunately, Io did not turn out to be a good clock. Rømer observed that times between eclipses got shorter as Earth approached Jupiter, and longer as Earth moved farther away. He hypothesized that this variation was due to the time it took for light to travel the lesser or greater distance, and estimated that the time for light to travel the diameter of the Earth's orbit, a distance of two astronomical units, was 22 minutes.

Unit 4: The Wave Nature Of Lightmr.'s Learning Website Free

  • The speed of light in a vacuum is a universal constant in all reference frames.
  • The speed of light in a vacuum is fixed at 299,792,458 m/s by the current definition of the meter.
  • The speed of light in a medium is always slower the speed of light in a vacuum.
  • The speed of light depends upon the medium through which it travels.The speed of anything with mass is always less than the speed of light in a vacuum.

other characteristics

The amplitude of a light wave is related to its intensity.

  • Intensity is the absolute measure of a light wave's power density.
  • Brightness is the relative intensity as perceived by the average human eye.

The frequency of a light wave is related to its color.

  • Color is such a complex topic that it has its own section in this book.
  • Monochromatic light is described by only one frequency.
    • Laser light is effectively monochromatic.
    • There are six simple, named colors in English (and many other languages) each associated with a band of monochromatic light. In order of increasing frequency they are red, orange, yellow, green, blue, and violet.
    • Light is sometimes also known as visible light to contrast it from 'ultraviolet light' and 'infrared light'
    • Other forms of electromagnetic radiation that are not visible to humans are sometimes also known informally as 'light'
  • Polychromatic light is described by many different frequencies.
    • Nearly every light source is polychromatic.
    • White light is polychromatic.

A graph of relative intensity vs. frequency is called a spectrum (plural: spectra).
Although frequently associated with light, the term can be applied to any wave phenomena.

  • A continuous spectrum is one in which every frequency is present within some range.
    • Blackbody radiators emit a continuous spectrum.
  • A discrete spectrum is one in which only a well defined set of isolated frequencies are present.
    (A discrete spectrum is a finite collection of monochromatic light waves.)
    • The excited electrons in a gas emit a discrete spectrum.

The wavelength of a light wave is inversely proportional to its frequency.

  • Light is often described by it's wavelength in a vacuum.
  • Light ranges in wavelength from 400 nm on the violet end to 700 nm on the red end of the visible spectrum.

Phase differences between light waves can produce visible interference effects.
(There are several sections in this book on interference phenomena and light.)

Leftovers about animals.

  • Falcon can see a 10 cm. object from a distance of 1.5 km.
  • Fly's Eye has a flicker fusion rate of 300/s. Humans have a flicker fusion rate of only 60/s in bright light and 24/s in dim light. The flicker fusion rate is the frequency with which the 'flicker' of an image cannot be distinguished as an individual event. Like the frame of a movie… if you slowed it down, you would see individual frames. Speed it up and you see a constantly moving image. Octopus' eye has a flicker fusion frequency of 70/s in bright light.
  • Penguin has a flat cornea that allows for clear vision underwater. Penguins can also see into the ultraviolet range of the electromagnetic spectrum.
  • Sparrow Retina has 400,000 photoreceptors per square. mm.
  • Reindeer can see ultraviolet wavelengths, which may help them view contrasts in their mostly white environment.