Energy can propagate through a medium or through what is currently believed to be a vacuum. Propagation modes vary depending upon the type of energy and the nature of the medium. Consider sound: It can travel through any material, solid, liquid or gas. In air, sound consists of waves, discrete like a single click, or […]
Basics of aliasing in sampled waveforms
Aliasing can have different meanings depending upon the context. For example, in computer programming it refers to instances where a computer program uses two or more different labels in different parts of the program to refer to the same data location. If the location is modified using one label, the change may cause difficulties in parts of the program that […]
Basics of Ethernet switches
In connecting computers to one another or to peripherals, the network switch has largely replaced the Ethernet hub, although the latter will still perform its intended functions. The difference is that the less advanced hub sends identical data between ports whereas the network switch (also known as a switching hub, bridging hub or MAC bridge) […]
Basics of optical fiber
Light is a form of electromagnetic radiation and as such it can be conveyed through a waveguide. The cross-sectional size of any waveguide depends on the wavelength of the energy that it will carry. Because light is at the high-frequency end of the spectrum, the waveguide through which it travels is slender although it may […]
Basics of understanding gain
Gain as a parameter is frequently used with reference to an amplifier, although other contexts are possible. It is the ratio of output amplitude or power of the output to the same value at the input. So that the number does not become unwieldy, a logarithmic decibel scale is ordinarily used. For an audio amplifier, […]
Determining the speed of light
Ancient people had a clear understanding of sound – how a vibrating object causes oscillating changes in air pressure, which move the eardrum so as to give rise to human perception of sound. In regard to light, there was less agreement. The pre-Socratic philosopher Empedocles believed light required a definite amount of time to travel […]
How to select an oscilloscope
by David Herres, Contributing Editor Here’s a quick review of what’s important to know about the wide assortment of scopes and scope features available today. Other than the multimeter, by far the most useful test equipment in an electronics lab or maintenance shop is the oscilloscope. In recent years, this instrument has evolved in unexpected […]
Solving problems in more than four dimensions
Immanuel Kant wrote in Prolegomena to Any Future Metaphysics (1783): “That everywhere space (which is not itself the boundary of another space) has three dimensions and that space in general cannot have more dimensions is based on the proposition that not more than three lines can intersect at right angles in one point. This proposition […]
The Many-Worlds Interpretation
of quantum mechanics
The Many-Worlds Interpretation of quantum mechanics was outlined in 1957 by Hugh Everett. Everett was a brilliant theoretician whose Many-Worlds theory failed to find support in his lifetime. His formulation is re-emerging as an important facet of contemporary thought in part because no less a thinker than Stephen Hawking is a strong proponent. Despite a […]
Basics of the National Electrical Code
and the Locations it Covers
The National Electrical Code (NEC) on its own has no legal status. It is managed by the National Fire Protection Association (NFPA) for the benefit of jurisdictions that wish to enact it into law. In the U.S., these entities are mostly individual states, although some states such as New York and Illinois delegate this function […]