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# Voltage,watt,amperage,resistance calculation

## Voltage,watt,amperage,resistance calculation

#1
01-22-16, 09:17 PM
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Voltage,watt,amperage,resistance calculation

Hello all , I'm beginer sorry in advanced if i make any mistake . I would like to be an electrician but i have some question if someone can help me to solve . In these days im usinig arduino electronic board in little electric project we can calculate resistance = voltage / current and voltage = current / resistance and current = voltage / resistance but my question is how i can calculate voltage,current,watt,ampere when we talking about home electricity . Thanks very much if anybody can help to teach formulas for home electricity

#2
01-23-16, 06:01 AM
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Welcome to the forums! To be honest, we don't do homework on the forums. But you can gain a great deal of information if you use the Ohm's Law pie chart.

#3
01-23-16, 07:09 AM
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Formulas

voltage = current / resistance
Recheck your work. This one is incorrect.

#4
01-23-16, 07:39 AM
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Electrons don't know they are whether they are running through house wiring or coming out of a battery. The formulas are the same. Voltages are always AC, generally calculations use 120 or 240. Because of length you need to factor in resistance in long wire runs.

#5
01-23-16, 11:11 AM
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Ohm's law (the above formulas) apply at all times in every electrical circuit or portion thereof.

It is difficult to predict the behavior of lighting circuits by measuring the resistances of the components because resistance varies, for example the resistance of an incandescent lamp varies with the temperature of the filament.

#6
01-23-16, 01:00 PM
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home wiring

thanks for your good answers but also in a home wiring we need to use resisters here i'm confuse little bit like we use resistors in little projects . if we have 110v and all switches , plug in a room they also need resisters ?

#7
01-23-16, 02:02 PM
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May be a Canadian thing, but why do you need resistors in home wiring?

#8
01-23-16, 06:51 PM
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i don't want resisters in home wiring i just want know for my knowledge to gain my electrician knowledge

#9
01-23-16, 07:31 PM
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I would suggest that you start with a good book on basic wiring. There are several available at the orange or blue box stores or through the internet.

#10
01-23-16, 07:32 PM
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You never put resistors in home or building wiring.

In the U.S. and Canada voltage is never a problem if it is between 110 and 120 volts and there is rarely a problem if the voltage goes up to 125 volts.

Nothing has zero resistance. So in reality an entire length of wire is one gigantic resistor. Gigantic in length although not gigantic in thickness or resistance.

For long (like over 100 feet) household and exterior circuits you use Ohm's Law to figure out the number of volts consumed (dropped) in the portion of the circuit consisting of the outgoing wire (repeat the calculation for the neutral wire) and if the voltage drop is too much for your liking (like more than 4 percent) then you choose a larger wire size (smaller resistance) or limit usage to fewer amps.

Now let's imagine that you put a resistor in a branch circuit to intentially reduce the voltage. Using Ohm's Law you will find out that the voltage remaining for the load (light, appliance, etc.) varies a lot depending on the amperes drawn. This is almost always very undesirable.

Ohm's Law is taught in college level science courses on electricity and might be taught in high school courses.

Last edited by AllanJ; 01-23-16 at 07:54 PM.
#11
01-23-16, 10:11 PM
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For Ohm's law resistors in residential wiring are mainly represented as loads. Light bulbs, computers, washing machines, air conditioners, pumps, etc. all have resistance.

Avoid inductance, reactance, and power factor as long as you can.

#12
01-24-16, 12:51 AM
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Ohm's Law is taught in college level science courses on electricity and might be taught in high school courses.
Ohm's law was certainly taught in my high school electricity classes, both on the theoretical level and as "light bulb analysis" in the laboratory sessions. Then again, since pretty much anything to do with Americanized English language is no longer taught it could be that electrical theory is no longer taught as well.

Avoid inductance, reactance, and power factor as long as you can.
What Astuff is really stating with this line is that Ohm's Law only applies to pure resistive circuits. Change to alternating current, add in capacitance or inductance and things change significantly. Polyphase circuits are another whole mind bender. Even after playing with electricity all my life I have problems with AC calculations.

#13
01-24-16, 06:18 AM
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When dealing with alternating current and capacitors (capacitance) and coils (inductance) complex arithmetic is used. (Complex numbers and complex arithmetic are actual buzz words in math and I learned about that in high school.) Some aspects of this can be discussed using 2 dimensional diagrams (X-Y plots) and arrows.

#14
01-24-16, 02:54 PM
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Hi just curious why it's wrong

#15
01-24-16, 03:01 PM
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Hi just curious why it's wrong
V=I*R rather than I/R....................