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A little help?

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AtoZ

New Member
Hey, I'm starting electronics but I admit I'm very confused on a couple of points. First, current flows from - to + or the opposite? Second, how can I calculate voltage divisors. What's the practical difference between voltage and amperage. And finaly, what's a ground? Is it only useful in AC currents?

Thanks guys
 

int12h

New Member
Lets take it step by step...

first: current flowing from + to - or - to +,...that is the question....it depends on who you talk to. Old school electronics guys like to say +to- ..acadamia will teach that it goes from -to+, because that is the actual direction the electrons flow...so your answer is..pick one :)

second: Voltage divider in a 2 resistor circuit will be Vunknown= Vin(R1/(R1+R2))
http://www.aikenamps.com/VoltageDividerRule.htm,.. also check the "Theory" part of electro-tech-online. It probably has info.

third: Voltage is actually "potential", or the difference in voltage levels from one point to another. Its the E in "E=IR". Amperage is the measure of 1 Coulombs per some seconds. It is the current in your circuit...how much water is flowing in the pipe. The I in "E=IR"

fourth: Ground is a reference point that should equal 0 volts. It is used in all circuits.

good luck,
bd
 

Phasor

Member
The last response by int12h has all the facts correct, but perhaps needs a little clarification - perhaps I can rephrase what int12h has said.

1) Current is talked about in two different ways - i) "Conventional current", and ii) "Electron flow". Before scientists discovered how electricity ACTUALLY flowed, it was assumed that current flowed from + to -. However, when the true structure of the atom was established, it was found that the electrons flowed from - to +. Despite this, we still generally use conventional current. Electron flow becomes important when investigating the operation of semi-conductors (transistors, diodes etc).

2) One should probably fully understand volts and amps before understanding voltage dividers...so on to 3...

3) An analogy is commonly made between electricity and water. In a water pipe, you have pressure, and flow. Pressure is like voltage, and flow is like current (amperage). When the tap is off, there is a large difference in pressure on either side of the tap (like a large voltage), but no water is flowing (zero current). Turn the tap on, and the pressure causes water to flow. If the pressure drops a bit, less water will flow. The same applies to electricity - drop the voltage, less current flows. Increase the voltage, and more current flows. Current flow is also related to resistance (like the diameter of the water pipe) - this is given the equation E=IR (you might also see it as V=IR).

4) I think int12h summed it up...
 
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