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Super Ultra Mega Post of Useful Information


New member
Aug 16, 2007
Hi All,

I know there is a mega-ton of information floating around here, and all someone has to do is SEARCH for the answer. And I know most of it is stickied into relevant threads etc. But sometimes some questions asked are about the basics of a subject. So I've come across a REALLY good website (http://visual.merriam-webster.com/), and I've just collated the bits loosely related to lasers and project builds etc. below. I take no credit for any of their work. I just thought I'd share it. I know I've used my fair share of asking stupid questions. I know some of the definitions are a bit obvious - but I put them in for completion.

@Mods: If you feel this is in the wrong section, feel free to move/sticky etc.



Oscillation caused by a disturbance; as it propagates through a medium (mechanical waves) or a vacuum (electromagnetic waves), it carries energy.

Mean Position:
Horizontal line around which the wave oscillates, carrying energy.

Distance between two consecutive crests or troughs; it corresponds to the distance traveled by the wave over time (its period).

Gap in relation to the mean position.

Highest point of the wave.

Lowest point of the wave.

Maximum displacement of a wave in relation to its mean position; it corresponds to the amount of energy transmitted.

Motion of a wave leaving its source.


Electromagnetic waves that are classified in ascending order of energy (frequency); they propagate at the speed of light (300,000 km/s).

Visible Light:
Electromagnetic radiation that is perceived by the human eye and ranges from red to violet.

Gamma Rays:
Electromagnetic waves of very high frequency that are emitted by radioactive bodies; they are the most radiant and harmful rays and are used especially in treating cancer.

Electromagnetic waves used especially in radiology; frequent exposure can be harmful.

Ultraviolet Radiation:
Electromagnetic waves used especially to tan skin and in microscopy, medicine and lighting (fluorescent tubes).

Infrared Radiation:
Electromagnetic waves emitted by warm objects; their many uses include heating, medicine, aerial photography and weaponry.

Short electromagnetic waves; their many applications include radar detection and microwave ovens.

Radio Waves:
Very long electromagnetic waves (about 1 meter) having low frequency; they are used to transmit information (television, radio).




Thicker in the center than on the edges; they cause parallel light rays emanating from an object to converge onto the same point.

Plano-Convex Lens:
Lens with one flat side and one convex side (bulging outward).

Positive Meniscus:
Lens where the concave side (curving inward) is less pronounced than the convex side (bulging outward).

Biconvex Lens:
Lens with both faces bulging outward.

Convex Lens:
Lens with one side bulging outward; the greater the bulge, the more the light rays converge


Thicker on the edges than in the center; they cause parallel light rays emanating from an object to diverge.

Plano-Concave Lens:
Lens with one flat side and one concave side (curving inward).

Concave Lens:
Lens with one side curving inward; the greater the curvature, the more the light rays diverge.

Biconcave Lens:
Lens with both sides curving inward.

Negative Meniscus:
Lens where the concave side (curving inward) is more pronounced than the convex side (bulging outward).


Device that produces a thin and very intense colored light beam; its various applications include fiber optics, manufacturing and surgery.

Laser Beam:
Straight and powerful monochrome light beam that is emitted by the device.

Cooling Cylinder:
Casing in which water generally circulates to cool the ruby cylinder, which becomes very hot as it produces the beam.

Fully Reflecting Mirror:
Reflects all the light energy toward the partially reflecting mirror. The reflection between the mirrors intensifies the light to form a highly concentrated beam.

Reflecting Cylinder:
Laser’s metal casing whose inside is polished so that it reflects the light toward the ruby cylinder.

Flash Tube:
Lamp that acts as an energy source by emitting a flash of white light, which excites the ruby atoms and causes them to emit photons.

Partially Reflecting Mirror:
Its partial transparency allows light beams to escape.

Energy particle that emits the ruby-chromium atoms as they are excited by flashes in the tube.

Ruby Cylinder:
Ruby bar (crystallized alumina) that contains chromium atoms. It has mirrors at each end, which form the amplification medium to produce the laser beam.



It is divided into independent branches, through which the current flows with partial intensity (in a series circuit, all the elements receive the same intensity).

Part of the circuit between two consecutive nodes; it constitutes an independent electric circuit.

Negative Terminal:
Polarity element of the battery from which the current flows through the circuit.

Positive Terminal:
Polarity element of the battery toward which the current flows through the circuit.

Direction of Electron Flow:
Electrons move from the negative terminal toward the positive terminal; this is opposite to the conventional direction of the current, which flows from the positive toward the negative.

Junction point of two or more branches in the electric circuit.

It enables each device to have its own circuit and to function independently. This way, if one lightbulb does not function, the current continues to flow in the rest of the circuit.

Gas sealed in a glass envelope into which the luminous body of a lamp is inserted.

Devices that transform chemical energy into electric energy in order to power electric devices (here, a lightbulb).

Device composed of one or more interrelated cells; each one accumulates a reserve of electricity whose purpose is to supply electricity to the circuit.

Power source:
The current leaves the battery by the negative terminal, flows through the circuit to power the lightbulbs and returns to the battery by the positive terminal.

Mechanism allowing the current in an electric circuit to be established or interrupted.


Usually plastic insulated card with holes containing electronic components; the circuit is printed on its surface.

Electronic component that regulates the amount of current flowing in a circuit.

Electrolytic Capacitors:
Polarized components with two conductive components (aluminum, tantalum) separated by an insulator (electrolyte); they store strong electric charge.

Ceramic Capacitor:
Component with two conductive plates (silver, copper) separated by an insulator (ceramic); it stores weak electric charge.

Plastic Film Capacitor:
Commonly used component with two conductive plates (aluminum, tin) separated by an insulator (plastic); it stores electric charge.

Packaged Integrated Circuit:
Electric circuit under a plastic or ceramic casing; it has pins for connecting it to the circuit board.
packaged integrated circuit

Printed Circuit:
All of the conductive metal bands on an insulated base (card), which connect a circuit’s components and allow a current to flow through it.


Battery that produces 1.5 V (also called Leclanché); its use is very widespread (pocket calculators, portable radios, alarm clocks).

Disk that compresses the depolarizing mix.

Sealing Plug:
Material that seals the battery.

Positive Terminal:
Polarity element of the battery from which the current flows.

Top Cap:
Upper metal cover; the positive terminal is located at its center.

Electrolytic Separator:
Porous paper combined with a chemical paste (ammonium chloride) that separates the two electrodes; this allows electrons to pass, thus conducting electricity.

Battery’s protective plastic casing.

Carbon Rod (Cathode):
Carbon rod set in the depolarizing mix; it constitutes the battery’s negative electrode (cathode) collecting the electrons returning from the circuit.

Depolarizing Mix:
Mixture of carbon and manganese dioxide that augments conductivity by acting as a barrier to polarization.

Zinc Can (Anode):
Zinc receptacle that constitutes the battery’s positive electrode (anode).

Bottom Cap:
Lower metal cover; the negative terminal is located at its center.

Negative Terminal:
Polarity element of the battery toward which the current flows.


Electric tool that is more powerful than a soldering iron; it uses finishing metal with a low melting point, such as lead, to join parts.

Cord Sleeve:
Protective casing around the cable to lessen twisting and prevent wear.

Case enclosing and protecting the device’s mechanism.

Pistol Grip Handle:
Part shaped like a pistol grip so the wrist remains straight while holding the tool.

Heating Element:
Electrical resistor that quickly heats the tip.

Metal part forming the end of the gun, used to heat a solder.

Metal wire that, by fusing over a joint, joins two parts.

Soldering Iron:
Electric tool with a tip for heating a solder, used to join parts that can take only weak mechanical pressure.


Device for measuring, among other things, a conductor’s resistance, the voltage between two points and the strength of the current.

Auto/Manual Range:
Button for choosing between the automatic and manual gauge for each function.

Metal tip connecting the multimeter to the circuit being tested.

Flexible electric wire housing the leads connecting the appliance to the electric circuit.

Input Terminal:
Socket for receiving a probe’s cord.

Selector Switch:
Device for selecting the desired function and the appropriate gauge for the measurement.

Data Hold:
Function for keeping certain readings in memory.

Digital Display:
Liquid-crystal screen displaying the reading taken by the device.


Wire Stripper:
Pliers with adjustable cutting jaws for removing the insulating sheathing from an electric cable or wire.

Adjustment Wheel:
Small striated wheel controlling the movement of the jaws so they adapt to the diameter of the electric wire being stripped.

Needle-Nose Pliers:
Pliers with long narrow jaws for doing delicate work or accessing hard-to-reach parts.

Lineman’s Pliers:
Pliers fitted with straight jaws that provide a powerful grip; they also include a wire cutter and jaws for pulling fish wire.

Straight striated part that, with its twin, opens and closes to grip, twist or cut an electric cable, wire or other object.

Wire Cutter:
Part fitted with two cutting edges for cropping an electric wire.

Pliers’ axle of articulation, which allows the jaws to open and close.

Insulated Handle:
Long part of the pliers, covered with a material preventing the flow of electricity.


international system of units
Decimal system established by the 11th General Conference on Weights and Measures (GCWM) in 1960 and used by many countries.

Difference in potential between two points of a conductor carrying a constant current of 1 ampere when the power between these points is 1 Watt.

Electrical resistance between two points of a conductor carrying a current of 1 ampere when the difference in potential between them is 1 Volt.

Unit of light intensity equivalent to a radiant intensity of 1/683 watts per steradian (solid angle).

Amount of electricity carried in 1 second by a current of 1 Ampere.

Amount of energy released by the force of 1 newton acting through a distance of 1 meter.

Energy transfer of 1 joule during 1  second.

Frequency of a periodic phenomenon whose period is 1 second.

Constant current of 1 joule per second in a conductor.

Phew!!! Finished! That took me about 1 hour to put together and correct (formatting).
Must be the longest post ever!  :D ;D

Dan :)


New member
Aug 16, 2007

I'm sure DDL will add it to the 'useful links' or something.
Maybe even a sticky? But that section is really full under the General section.

Dan :)


New member
Aug 15, 2007
I don't care if it's a bit full, just delete one of the other threads. We need this stickied!
Great work Dan. (and outstanding subject title ;))


New member
Aug 16, 2007
Whooo! High score!
Shame this can't be a sticky - what with there being no mods and all! ;D
And thank you.

Dan :)