Saturday, 13 February 2010

Some terms to remember for lecture on Illumination engineering

In mathematics, the root mean square (abbreviated RMS or rms), also known as the quadratic mean, is a statistical measure of the magnitude of a varying quantity. It is especially useful when variates are positive and negative, e.g., sinusoids.

Periodic Signals are signals that repeat themselves after a certain amount of time. More formally, a function f(t) is periodic if f(t + T) = f(t) for some T and all t. The classic example of a periodic function is sin(x) since sin(x + 2 π) = sin(x). However, we do not restrict attention to sinusoidal functions.


The quintessential periodic waveform. These can be either Sine functions, or Cosine Functions.

Square Wave

The square wave is exactly what it sounds like: a series of rectangular pulses spaced equidistant from each other, each with the same amplitude.

Triangle Wave

The triangle wave is also exactly what it sounds like: a series of triangles. These triangles may touch each other, or there may be some space in between each wavelength.

Easy way to express

Sinusoidal voltage is rms. Root Mean Sqaure

Periodic signal one that is repeated after certain amount of time.

single phase ac generation

Electronics/Magnetic Field

The generation of AC electric power is commonly three phase, in which the waveforms of three supply conductors are offset from one another by 120°. The design of the power generators has three sets of coils placed 120 degrees apart rotating in a magnetic field. This creates three separate sine waves of electricity that are displaced from each other in time by 120 degrees of rotation (1/3 of a circle). Standard frequencies of rotation are either 50 Hertz (cycles per second) in Europe or 60 Hertz in North America.
Electric Maintenance Fundamentals - AC/DC Theory
When we can get electrons to flow away from their atom in a single direction we have electricity.
Silver , glass, aluminum good conductors.
Insulator plastic, dry wood, rubber
turning crank on generator forces electrons through conductor.