'puter 'ponents

I believe that it is important for everyone to be able to recognize and understand the usage of the basic computer components.
This thread is merely listing and defining some of the more basic (and important) computer components. I have chosen to put it here in the hardware forum since - well, it just seemed like an appropriate place for it.

Seasoned vets and Gurus turn back now - this is not meant for you!!!

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Transistor - Amplifies a signal or opens and closes a circuit.

Integrated Circuit - An electronic device made out of semiconductor material (material that can control the amount of electricity it conducts).

Resistor - A device that offers resistance to the flow of an electric current.

Capacitor - Electric component that stores energy in the form of an electrostatic field; it consists of 2 conducting metal plates separated by an insulating material.

Connector - The part of a cable that plugs into a port or an interface.

Light Emitting Diode (LED) - A device that lights up when electricity passes through it.

Printed Circuit Board (PCB) - A thin plate on which chips and other electronic components are placed.

Central Processing Unit - The brains of the computer where most calculations take place.

Microprocessor - A silicon chip that contains a CPU. Microprocessor and CPU are usually interchangeable.

Motherboard - Main circuit board of a personal computer.

Bus - Collection of wires through which data is transmitted from one part of a computer to another. It connects all the internal computer components to the CPU.

Random Access Memory (RAM) - A type of computer memory where any byte of memory can be accessed without touching the preceding bytes.

Read-Only Memory (ROM) - Computer memory on which data has been prerecorded; after data has been written onto a ROM chip, it cannot be removed and can only be read.

System Unit - The main part of a PC; the system unit includes the chassis, microprocessor, main memory, bus, and ports, but does not include the keyboard, monitor, or any external devices cnnected to the cmputer.

Expansion Slot - An opening in a computer where a circuit board can be inserted to add new capabilities to the computer.

Backplane - The large circuit board that contains sockets for expansion cards. A backplane is distinguished from a motherboard by the fact that it might contain almost no logical circuitry for performing computing functions.

Network Card - An expansion board inserted into a computer so the computer can be connected to a network.

Modem - The modem (modulator/demodulator) is a device that enables a computer to transmit data over telephone lines; there are internal (installed as expansion cards) and external (connected to ports) modems.

Interface - A piece of hardware, such as an electrical connector, that allows 2 devices to be connected together.

Port - An interface on a computer to which you can connect an electronic device.

Parallel Port - An interface capable of transferring more than one bit simultaneously. It is used to connect external devices such as printers.

Serial Port - An interface that can be used for serial communications (data comunication in which only 1 bit is transmitted at a time).


Data Flow

Boot instructions - Stored in ROM until they are sent out.

Software Applications - Stored in RAM after they have been loaded.

RAM and ROM - Constantly talk to the CPU via the bus

Application Information - Stored in RAM while applications are being used.

Saved information - Flows from RAM to some form of storage device.

Exported information - Flows from RAM and the CPU, via the bus and expansion slots, to the serial port, parallel port (usually for printers), video card, sound card, or network card.
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All definitions and information are from the Cisco Networking Academy

oh ****... you made this up right?

Betterdo some research before I come back.. and pick this list to peices..

Regardles of wether this list is for beginners or not.. IT IS BLOODY WRONG

As credited at the bottom of the list - all the definitions are taken from Cisco .......... Personally I know what all these components are and they all seem accurate to me - unless I overlooked something ........

Be very interested to hear what you see wrong with it.

I'd start with the Capacitor, most capacitors are electrolytical capacitors (not the electrostatic kind).
They are more like a battery.. With layers of conductive and non conductive material drowned in an acidic electrolyte..
I'm also missing diodes (one way flow-restrictors) and some other components..

(pardon my spelling on any of the words, English is not my first language)

Give him some credit man... half of it's right.

Integrated Circuit - An electronic device made out of semiconductor material (material that can control the amount of electricity it conducts).
Wrong. A resistor is made of semiconducting material. A resistor is not an integrated curcuit. An IC consists of many components.

Light Emitting Diode (LED) - A device that lights up when electricity passes through it.
Half wrong. An incandescent, flourescent, or halogen lightbulb does that too.

Microprocessor - A silicon chip that contains a CPU. Microprocessor and CPU are usually interchangeable.
Wrong. A microprocessor does not contain a CPU. It is small, and processes information. Hence the term microprocessor. It may in fact be a CPU. It does not, however, contain a CPU.

Bus - Collection of wires through which data is transmitted from one part of a computer to another. It connects all the internal computer components to the CPU.
Wrong. A bus, in terms of computers, is not a collection of wires. This may confuse people with the power supply wires. A bus, physically, is usually laid out as ultra thin copper conduits on a circuit board. It can also be an entirely logical device.

System Unit - The main part of a PC; the system unit includes the chassis, microprocessor, main memory, bus, and ports, but does not include the keyboard, monitor, or any external devices cnnected to the cmputer.
More commonly referred to as the case or the box.

Backplane - The large circuit board that contains sockets for expansion cards. A backplane is distinguished from a motherboard by the fact that it might contain almost no logical circuitry for performing computing functions.
Wrong. Expansion cards are connected to the rest of the computer by means of a bus. Typically today, this is an ISA bus. It is, in fact, an integral part of the motherboard. On desktop models (as opposed to tower models), this usually requires the use of a riser card, which may be what you are referring to as a backplane. This rises from the motherboard vertically to allow expansion cards to sit horizontally, parallel to the motherboard. The term riser card is far more frequently used.

Network Card - An expansion board inserted into a computer so the computer can be connected to a network.
Half correct. A network card may in fact be integrated into the motherboard by means of a microprocessor on it. In other words, computers may in fact be connected to a network without the addition of a network card.

Interface - A piece of hardware, such as an electrical connector, that allows 2 devices to be connected together.
Half right. An interface may be a piece of hardware, or it may be a logical interface as well. Your operating system is in fact an interface between you and your hardware.

Port - An interface on a computer to which you can connect an electronic device.
Half right. A port can be an entirely logical concept. This definition gives the impression that it is in fact a physical device only. While there are parallel, serial, usb, etc... ports on the computer, there are also logical ports, through which you can communicate via a network. Web surfing, for example, uses port 80, so the computer knows which program to send the web data to.

Boot instructions - Stored in ROM until they are sent out.
Half right. The only boot instructions in ROM tell the computer where to find more boot instruction, such as the first sector of a hard drive, or maybe a USB stick or floppy drive. It says, in essence, "go to hard drive 0, sector 0, and then do whatever that tells you to."

Software Applications - Stored in RAM after they have been loaded.
Half right. Only the necessary parts of most applications are loaded into RAM. Most of it isn't, in order to save memory. If you loaded all of Word when you started it, you would never have enough memory.

I don't care if this is from Cisco. They're wrong too, then.

Hopefully that clears a few things up.

Seasoned vets and Gurus turn back now - this is not meant for you!!!

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Transistor - Amplifies a signal or opens and closes a circuit.

Integrated Circuit - An electronic device made out of semiconductor material (material that can control the amount of electricity it conducts).

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Transistor stands for Transfer of Resistance
You can use a transistor in a circuit to act as a basic Amplifier or a Switch.. It is constructed out of a Semiconducting material such as Silicon or Germanium

Now the Intergrated Circuit.. AS ITS NAME WILL IMPLY.. is An intergration of of Circuit Components, such as FET's (Field Effect Transistor), Transistors, Diodes, resistors, Capacitors and Very low value Inductors.. the this circuit can be any thing from a electronic switch to a CPU core..

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Resistor - A device that offers resistance to the flow of an electric current.

Capacitor - Electric component that stores energy in the form of an electrostatic field; it consists of 2 conducting metal plates separated by an insulating material.

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good enough for beginners.. Resistance is measured in Ohms, Capacitance in Farads (any know why those names.. now no cheating Google searches are banned..I am watching)

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Connector - The part of a cable that plugs into a port or an interface.

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Hmm well.. other wise known as Plugs? hmm well sort of.. it is the device that allows cables/cards to connect to other cables/cards etc.. Two parts.. You have the Plug..and ..The Socket..
USes.. Data path, Radio signals, Power..etc

Check out, Edge Connector, PCI Socket, P/S2 Connector, IDC, IDE, RCA, Phono.. DC

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Light Emitting Diode (LED) - A device that lights up when electricity passes through it.

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LOL.. So a Incandecent Light Bulb is a LED... And that 33ohm REsistor I connected across the 240V mains is also a LED?

LED.. Light Emitting DIODE.. IS a Diode (Thermionic or Semiconductor) that when it is forward Biased (ie a current is passing through the device) will emit light

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Printed Circuit Board (PCB) - A thin plate on which chips and other electronic components are placed.

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Well sort of.. but a plate? dinner Plate?
How about A thin sheet of Dialectric material, usually with a coating of copper, this coating etched to create a electrical paths (Circuit), for the mounting of electronic components, including resistors, capacitors, IC's (intergrated Circuits), Cpu (**** another IC).etc..

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And that 33ohm REsistor I connected across the 240V mains is also a LED?

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Nope. For a brief instant, it's a small bolt of lightning. Then it's just no longer a resistor.

Of course, it could be a stove element, too.

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Capacitor, most capacitors are electrolytical capacitors (not the electrostatic kind).

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Actualy..... Electrolytic is a TYPE of Capacitor, like polyester, styroseal, Mica and Ceramic.. this refers to the type of dialectric that is used..

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They are more like a battery..

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that is infact a good description for a capacitor.. you can use a Capacitor as a battery. Where most of the capacitors we see in circuits are in the Milli and Micro farads. a battery would be considdered as being in the FArads.. but a capacitor with the same capacity of a battery you dont want to touch.. those ****ers kill.. I have seen a guy planted by a 1 Farad 12V capacitor.. I was off work for 3 months from a 100uf 400V ..thrown 8 feet, blinded for half an hour.. and my heart took all of the 3 months to settle down..

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Nope. For a brief instant, it's a small bolt of lightning. Then it's just no longer a resistor.

Of course, it could be a stove element, too.

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Well the later is close.. A length of NiChrome Wire.. a bright red glow.. and it will run like this for a few hours (the resistance is relitivley stable compared to a light bulb element or a electric jug element) .. it is close to its rating when it glows.. lol

I did misword the definition of microprocessor - apologies!!!!

As for the others that have been deemed as 'half rights' - you considered them half wrong because I just use a very short, simplified form of the definition rather than go into too much detail (or unnecessary information that was not included, rather than the information that was included).

And sorry - I did not post a very good definition for bus either - I never even considered it would be thought of as actual wires that flop around loose and get tripped over - but reading your post I can see why it would have been interpretted that way.

What I have always called and thought of as a backplane was the board that the expansion slots are attached to with the buses running from/to them - I know what a riser card is and I have never heard of backplane and riser card used interchangeably - assuming I correctly understood your explanation.

As for the LED definition - I never said that it was the only device that lit up when electricity passed through it nor did I say that all devices that emit light when electricity passes through them are LED; I said it was a device that lit up when electricity passed through it

I wasn't using Cisco as a validator to the accuracy of the definitions - I had said that as a response to Undertaker asking if I made this up.

But cheers - the nit - picking (I say that in a good way) will definately encourage me to raise my standards to greater heights .........

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As credited at the bottom of the list - all the definitions are taken from Cisco .......... Personally I know what all these components are and they all seem accurate to me - unless I overlooked something ........

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Better send a copy of the page.. your link was just Cisco's home page, now I am a bit lazy I couldnt find any thing that looked like the list you gave.... I realy would like to see what they are teaching.. If their BASIC electronic's training is ****.. I wont be paying for any Cisco hardware AGAIN....
If any of my staff were trained with that crap.. I wouldnt even have them in Manchester sales..

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But cheers - the nit - picking (I say that in a good way) will definately encourage me to raise my standards to greater heights .........

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Yes.. true.. and good to see.. If I thought you were a loser I would have just Negged and moved on.

My first post in this thread I asked you to research and correct.. please to raise your standards.. do this..
Answer this..
in one of my comments I mentioned Thermionic and semiconductor, I could have used Solid State for the latter.. why.. what is the difference between Solid State and Thermionic?

What are some of the different type of transistor.. (geeez that is open)

Any one else want a go at these? Wait for Memys reply then post your answers..

Cheers

I have to agree with you, Undertaker ..........
I am becoming skeptical too

I have always been software and internet oriented in my knowledge and expertise and it has only been recently I have pushed to delve into the hardware side of it all - beyond the basic, integral and necessary knowledge accumulated through years of mucking about with things.

Most of that info. was taken from a textbook - of all things

I'v scanned the first page for you and it follows ...............

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Resistance is measured in Ohms, Capacitance in Farads (any know why those names.. now no cheating Google searches are banned..I am watching)

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Because of Ohms law, which isn't really a law, but more a definition of resistane. I think its the guy's name as well. As for Farads, I seem to recall that was the mans name as well...

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LOL.. So a Incandecent Light Bulb is a LED... And that 33ohm REsistor I connected across the 240V mains is also a LED?

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Of course it is... That's how LEDs work. They resist the electric current, and cause the air to light up inside the bulb IIRC.

Actually, when electric current enters the diode, the electrons on one side of the diode become excited and move to a higher energy state, absorbing electrical energy. When they move across the diode to the other side, they drop back to a lower energy state. When this happens, they release that energy in the form of a photon, which we interpret as visible light.

So LEDs turn electrical energy directly into light energy, which is why they are so efficient. An incandescent bulb, on the other hand, simply heats the filament to the point where it is so hot that it gives off light, just like metal can be heated to give off light.

Just my 2 cents...

I started this post to be informative for others.

[irony]
I have learned more from it than I even imagined I would have been teaching others when I started it :p
[/irony]

Thanks all

Memy

That is more a Kindergarten Basic intro to electronic components, they certainly dont want you knowing too much in that area..

there is big difference between being able to identify a component, knowing how it works, knowing how it is working in the circuit, knowing what component is the most likely suspect when some thing is wrong.. that is the difference between healthy and Sick/dead..
The diference is what your doing with the circuit..



BTW: here is a site I found in a quick search.. the link is more for the abreviations lists.. It seems mostly OK..
http://www.twysted-pair.com/abbreviations.htm
On the home page there.. they talk about a first lesson Download.. I have no idea how good it is.. so be careful if you do d/l it..

Actually its from one of their college level text books ........ That was just the very first page - it gets a bit more involved, I just couldn't be assed to scan any more pages - as you probably couldn't have been assed to read anymore of them.

But like I said hardware has never been my forte - its something I have recently been paying more heed to in my push to know everything :p

BTW that is a really good site you posted - I will be making good use of it over the next few weeks.

I was tempted to grab a couple of my Text books and scann a few pages for you.. but being lazy.. google.. found a few gems..

Here is one that goes into better detail on many components..
http://www.radio-electronics.com/info/data/index.php

Give this one to your trainer:
http://sound.westhost.com/beginners.htm#3_0

it looks bloody beaut mate
and what I have read.. not to bad.. prolly a bit advanced in some parts..for absolute beginners .. you should be ok..(yell if ya need help)

now I will stop annoying you.. if you want more.. just yell

ciao

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(any know why those names.. now no cheating Google searches are banned..I am watching)

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Sure even though it's been 15 years now since BEE - Ohm was the cat's name who invented Ohm's Law, the rule which govern's electrical circuits - that being the voltage equals the current times resistance (E=IR). I'm pretty sure he was the one who realized that all lights, motors, and any other load one could put in a circuit was a resistor, and the one who developed a unit of measurement for resistance, which he proudly named Ohms. The really cool thing is that conductivity (used extensively by the boiler technicians of the world) units are measured in Mho's....Ohm backwards. As for our friend Farad, he's who developed the first working dielectric capacitor, and the units with which we measure capacitance. We honor his name my calling those units Farads.

I'm quite surprised you didn't introduce our newbie friend to KVL, but then again judging from his sub b- work posted above, perhaps he's not ready for it yet.

I won't address your transistor issues yet since you're waiting on our newbie, but I'll pretend I made a crude comment about a xener diode here :D

Faraday... may have something to do with some of this..

who manages to catch the Faraday Lecture each year on BBC (i think..we just have Absolute Bloody Carelessness ..ABC in OZ).. I have missed the past couple of years.. but it would rate as an excellent resource for high school students.. excellent primer for those interested in any area of electronics, communications, computers..

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Resistance is measured in Ohms, Capacitance in Farads (any know why those names..

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Mr Ohm and Mr Farad ?
Although the Farad is FAR too large a unit, and is invariably expressed as micro-farads

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What are some of the different type of transistor..

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I've got one that will play radio 1 :D

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what is the difference between Solid State and Thermionic?

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A thermionic device contains a cathode that emits electrons only when heated.
A solid state device uses semiconductors to generate electrons and does not use a heater.

A thermionic device requires a vacuum to allow electrons to flow between the electrodes, they are packed in evacuated glass tubes.
Solid state devices operate at normal air pressures and are packed in plastic.

Solid-state devices are smaller than thermionic devices.

Me is/was electrical engineer, suprised myself how much bumf I still remember :)
When I started, solid state was REALLY solid.
and the memory of throwing old valves [thermionic emitters] into skips, and dodging the flying glass .......... Ahh, those were the STUPIDEST days of my life :D

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Capacitance in Farads (any know why those names.. now no cheating Google searches are banned..I am watching)

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No Googling, and I can prove it:

Farads, a standard unit of capacitance due to it's inventor Michael Faraday.

Ohms, from inventor of Ohms law, don't remember the name, (Billy Joe Bob Ohms?)

Resistor, some one who resists paying their taxes

Transistor, What you call your brother when he's wearing your sister's clothing.

Okay..okay...at least the first one is right.

:D

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Mr Ohm and Mr Farad ?
Although the Farad is FAR too large a unit, and is invariably expressed as micro-farads

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So are amps in most cases, it really just depends on what you personally happen to be working with...

Ok, now the google answers since I just had to go look...

http://www-groups.dcs.st-and.ac.uk/~...cians/Ohm.html

for information about Georg Simon Ohm

and

http://scienceworld.wolfram.com/biography/Faraday.html

for Michael Faraday

Georg was a mathmetician, Michael a bookbinder. For further info click the links.

For Solid State and a good definition, check
http://whatis.techtarget.com/definit...500174,00.html

and for Thermionic look at
http://www.bartleby.com/61/65/T0156500.html
for a definition and
http://www.thermionic.org/
for a breadboarded picture integrating a thermionic tube.

For Transistors check
http://www.interq.or.jp/japan/se-inoue/e_transist.htm

Damn that brought back memories... npn, pnp... I still like calling folks zener (xener?) diodes though - In semi-acceptable language a zener is a one-way mofo :D

Now if we're getting into stuff, I'd like to see our beginning electronics newbie define

a coulomb, and what it is in relation to the definition of a volt,

the definition of one amp,

and what is dielectric constant in relation to capacitors (since we were on farads earlier I thought this would be an interesting thing to look at..)

Oh, and what, in electrical terms, do the letters RC mean, and how are they related to the formula 1/lRC? (no, not remote control...keep at it).

No googling at least until several hours have passed ;)

1 amp = 1C/s IIRC
Coloumbs are the amount of power flowing during a specific time period...
RC.... RC.... dangit, where'd it go? *Smacks head* Someone else can answer that one...

Dielectric constant... Is that the rule that states everythign that goes in comes out?

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Dielectric

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To Die Electricly..?

(oh bugger.. I am fighting with a smoothwall installation that dosent want to update ..I'll come back to this when I have beaten the box to a pulp)

Valiant Efforts indeed!

First we must define Voltage. Voltage is a difference in electrical potential between two points.

Now we add in the definition of one volt -

1 volt equals a difference in potential of one coulomb of charge between 2 points. It is important for the electrician to remember that volts are stationary, amps do the moving as I'll define in a sec.

1 coulomb of charge is approximately equal to 6.24506 times 10^18 electrons. It is so named for Charles-Augustin de Coulomb, the first to measure it and equate it to a Volt.

1 amp is the movement of that coulomb of charge across the two points, which will occur when voltage is present. Yes, I learned electron flow theory. For those of you who learned hole flow theory, there's a whole different school of thought here.

dielectric constant is the measurement of how well the dielectric material between the plates of a capacitor will permit electrical flow. It is important in that the dielectric material is what contains the electrons when the capacitor charges. When you discuss Farads, this is what you're discussing.

RC - Resistance times Capacitance - is the formula for calculating the length of time it will take a capacitor to charge within a capacitive circuit. For a very good source on this I strongly recommend
http://othello.mech.northwestern.edu...k/elec5/RC.htm
It's one of the best I've seen since A school.

1/lRC - is the formula for calculating the time it will take a capacitor to charge in an inductive circuit. In plain english, it is read as the inverse of inductance times resistance times capacitance. Unfortunately I wasn't able to find a source on my first page of googling and I was too lazy to look further. It's out there, I promise. The page on RC time constants talks all around it but never does mention this particular formula.

And finally I'll add in KVL since it was one of my favorites and got my butt out of cracks many times. Kirchoff's voltage law, which states basically that everything in a circuit except the voltage, when added together, will equal the voltage. (all things equal zero).


[edit]I fixed the missing 'm' in the link so it should work now[/edit]

I knew right when I read the first def it was going to be a no holds barred, Guru warning no guru warning.

Anyway, I just like to add some other important devices in.

MOSFET The MOSFET, or Metal-Oxide-Semiconductor Field-Effect Transistor, is by far the most common field effect transistor in both digital and analog circuits. The MOSFET is composed of a channel of n-type or p-type semiconductor material (see article on semiconductor devices), and is accordingly called an NMOSFET or a PMOSFET. Usually the semiconductor of choice is silicon, but some chip manufacturers, most notably IBM, have begun to use a mixture of silicon and germanium (SiGe) in MOSFET channels. Unfortunately, many semiconductors with better electrical properties than silicon, such as gallium arsenide, do not form good gate oxides and thus are not suitable for MOSFETs.

The gate terminal is a layer of polysilicon (polycrystalline silicon; why polysilicon is used will be explained below) placed over the channel, but separated from the channel by a thin layer of insulating silicon dioxide. When a voltage is applied between the gate and source terminals, the electric field generated penetrates through the oxide and creates a so-called "inversion channel" in the channel underneath. The inversion channel is of the same type—p-type or n-type—as the source and drain, so it provides a conduit through which current can pass. Varying the voltage between the gate and body modulates the conductivity of this layer and makes it possible to control the current flow between drain and source.


Chipset/Northbridge/Southbridge Chipset refers to a group of integrated circuits ("chips") that are designed to work together, and are usually marketed as a single product.

In computing, the term chipset is commonly used to refer to the specialized motherboard chips on a computer or expansion card. When discussing personal computers (PCs) based on recent Intel Pentium-class systems, the term "chipset" often refers to the two main motherboard chips: the northbridge and southbridge. The manufacturer of a chipset can be, and often is, independent from the manufacturer of the motherboard. Examples of PC motherboard chipsets include NVIDIA's nForce chipset and VIA Technologies' KT800, both for AMD processors, or one of Intel's many chipsets (see, for example, [1] (http://developer.intel.com/design/chipsets/)).

The term "chipset" was also widely used in the 1980s and 1990s for the custom audio and graphics chips in home computers, games consoles and arcade game hardware of the time. Examples include the Amiga's Original Chip Set or SEGA's System 16 chipset.

Computer systems produced since the late 1980s often share commonly used chipsets, even across widely disparate computing specialties—for example, the NCR 53C9x, a low-cost chipset implementing a SCSI interface to storage devices and the like, could be found not only in UNIX machines (such as the MIPS Magnum), but also in embedded devices and personal computers.

Found at: http://en.wikipedia.org and I'd suggest you run all them above for the correct information.

Micro Cool Heatsinks for MOSFET's I cool mine just because I can.....plus, adds to better, steady voltage.

I commend every who posted in this thread. While there wasn't a lot of agreement with the original post, rather than neg it into oblivion everyone put in their 2 cents and created an informative post. I also give credit to Memy for willingness to take constructive criticism rather than pout and lash out in response.

Good job all around.

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I commend every who posted in this thread. While there wasn't a lot of agreement with the original post, rather than neg it into oblivion everyone put in their 2 cents and created an informative post. I also give credit to Memy for willingness to take constructive criticism rather than pout and lash out in response.

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This thread could have ended on the first page in flames, memy could have left in disgust.. instead it has become a pseudo-electronics tutorial.. good..

Now I add three more questions:

1/ A short Curcuit.. what is it..How does it cause house fires? ..or maligned malingerer?
Why isnt there a Long Curcuit? and could it be the hidden partner in crime.. or is it just not a sexy name..?

2/ Impedance and resistance.. the same thing or completly different
.. what are the differences..?

3/ Heating of components, Power=EI is one.. but some components Transistors/FET's in certain circuits "over Heat" but the circuit current is no where near the components rating and nor is the voltage.. so why?


We've had some bloody good posts here, how about a couple of new faces.. (btw.. if you do google/use a web reference on this one.. please post the links you used..

1. The insulation on wires sitting next to each other gets worn out, the two wires create another circuit (hence, short circuit) the resistance become less, the wires are getting all the electricty and none of the devices are, so they heat up and cause fires.

2. Impedance is resistance at certain frequencies IIRC...

I hid it since you said you wanted fresh faces in on this.

From rote memory, which may be inaccurate to a pont:

A short circuit is when power passes directly from path to return or ground, completely bypassing the load (light, outlet, etc.) It causes a condition called 'overcurrent' which generates much heat and can cause fires. Fuses and breakers are devices intended to halt this when it occurs, using a thermally activated 'switch' which either breaks (in the case of fuses) or separates (trips - in breakers) when overcurrent is sensed. There is no 'long circuit' referred to in electrical theory, but by definition I would call it the opposite of a short circuit, or a circuit which is functioning as it is intended.


Resistance is anything that causes a voltage drop within a direct current circuit. These drops are measurable using Ohm's law. They can be motors, lights, relays, or anything that requires power to function. In the broadest sense, they are anything that can be put into an electrical circuit other than the power supply, including inductors and capacitors although these are treated somewhat differently in calculating the circuit values.

Impedence is resistance within an alternating current circuit. The formulas for calculating impedence are quite different from those used to calculate resistance, which is why there is a differentiation. The formula for impedence takes into account the fluctuations of voltage on each phase (sine wave AC), and the phase differential between phases of AC. Impedence, like resistance, is measured in Ohms.

Couple more cool add-ons:

Energy can neither be created nor destroyed, merely altered in form.
(law of conservation of mass and energy)

There is no such thing as a 100% efficient machine.
(2nd law of thermodynamics)

So read in order, and combining the two.... You cannot win, You cannot lose, and you cannot break even. :D