Category: Light As A Wave

Lastly, if you built at least one of the units to act as both a transmitter and receiver, you essentially have the heart of a police radar gun, and you may want to experiment with the interesting wave property of light called the Doppler effect. Connect the Gunnplexer’s detector diode output (mixer output) to an…

A double-slit experiment with 3-cm microwaves will give you the basic understanding of how double-slit experiments are conducted in sophisticated quantum research that we will discuss in chapters 7 & 8. Just as so many of the other specialized particle detectors, the Gunnplexer receiver does not produce an image, so the interference pattern needs to…

As you collect data, remember that Gunnplexers, stripboards, and other microwave components do not behave exactly as do their ideal, theoretical counterparts. For example, data from real Gunnplexers approximate, but do not exactly lie on, the ideal curve of Figure 13b. You should also have observed that stripboards are far from ideal polarizers, since they attenuate…

Let’s start by experimenting with a polarizer that is actually made out of wires, such as the one shown in Figure 10. However, we’ll need a source of electromagnetic waves with sufficiently large wavelength. Fortunately, it is easy to generate and detect microwaves with a wavelength of around 3 cm, making it possible to experiment with…

Polarization is an important characteristic of light that Maxwell’s electromagnetic theory was finally able to explain. Notice in Figure 8 that the electric field is shown to oscillate in one plane, while the magnetic field oscillates on a perpendicular plane. The wave travels along the line formed by the intersection of those planes. The electromagnetic wave shown in…

Later, in the 1860s, Scottish physicist James Clerk Maxwell identified light as an electromagnetic wave. Maxwell had derived a wave form of the electric and magnetic equations, revealing a wave-like nature of electric and magnetic fields that vary with time. Maxwell figured out that an electric field that varies along space generates a magnetic field…

Diffraction, reflection, and color are also explained by Young’s wave theory. However, interference is the calling card of waves, so Young’s experiments convinced many in the early 1800s that light is indeed a wave. In spite of this, Newton’s reputation was so strong, that his particle model of light retained adherents until 1850, when French…

Accurately measuring interference patterns from projections on a screen is rather tedious. However, you can build a simple device that makes it possible to display interference patterns on an oscilloscope, making it easy to measure not only the distance between fringes, but also their amplitude. As shown in Figure 5, the idea is to use a…

Around 1801, Thomas Young discovered interference of light. This phenomenon is only possible with waves, providing conclusive evidence that light is a wave. In Young’s experiments, light sent through two separate slits results in a pattern that is very similar to the one produced by the interference of water waves shown in Figure 2. Figure 2 Water…

In 1704, Sir Isaac Newton proposed that light consists of little particles of mass. In his view, this could explain reflection, because an elastic, frictionless ball bounces off a smooth surface just like light bounces off a mirror—that is, the angle of incidence equals the angle of reflection. Remember that Newton was very interested in…