# amperage question....

Discussion in 'General Electronics Chat' started by odm4286, Sep 20, 2009.

1. ### odm4286 Thread Starter Active Member

Sep 20, 2009
155
5
Ok guys I know this is some basic stuff some bare with me. So far ive come to understand that voltage is like psi, resistance is like a larger pipe it will decrease psi, and amps is the amount of electrons at a given second in a circuit or the amount of water if we use that analogy.

Now my question is what exactly is used to increase the amperage of a circuit. Like would a 5inch thick piece of copper in a circuit generate more amps then a 2inch thick piece since theoretically there would be more "free electrons" in the larger conductor. Or is the power source the factor that determines the amperage and if so how does one power source generate more amps then the other.

2. ### GetDeviceInfo Senior Member

Jun 7, 2009
1,571
230
well, if you wanted to flow more water, you'd either increase the pressure, or increase the diameter of the pipe.

Increasing the pipe size may not matter however if an orifice is restricting flow.

3. ### russ_hensel Distinguished Member

Jan 11, 2009
820
47
While not entirely correct we usually think of voltage as causing current. How much depends on the resistance. So low resistance => high current.

You seem to have the basic idea ok.

4. ### odm4286 Thread Starter Active Member

Sep 20, 2009
155
5
ok so a larger gauge wire would lower voltage (as there is less resistance) and increase amperage? Also since in order to get through the resistance of human skin you would need about 50 volts...is it true you could have a 1000 amp circuit running at 10 volts and you could touch it and never feel a thing

5. ### beenthere Retired Moderator

Apr 20, 2004
15,815
283
In the case of your coming in contact, the voltage is most important. Any current in the conductor is immaterial to the potential you feel, as that voltage is what may drive current through your body. Generally speaking, any voltage under 12 is considered to be inherently safe - that is, not a shock hazard.

The resistance of human skin is affected strongly by variables like moisture and local thickness.

Do not depend on the diameter of the wire to control voltage. The equation that governs is E (voltage) = I(current) * R(resistance). The greatest effect of wire gauge is more likely to be that the larger wire carrying a given current will not get as warm.

6. ### odm4286 Thread Starter Active Member

Sep 20, 2009
155
5
ok im sorry I know this is probably trivial to you guys but im just trying to wrap my head around this stuff. As far as the larger wire only handling heat better wouldn't it not generate more amps as well as it contains more copper(or any other conductor) which in turn contains more "free electrons"

7. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
Wire does not "generate" current, like copper or PVC pipe does not "generate" the flow of water.

Electrical current (flow of electrons) is roughly equivalent to water flowing through a pipe, or down a river.

Voltage is electrical pressure, roughly analogous to PSI in a water plumbing system.

The diameter of a wire is roughly analogous to the diameter of a pipe, or the width of a river.

For a given pressure, more water will flow in a larger pipe than in a smaller pipe due to the turbulence in the pipe. If the pressure is too great, the pipe will burst.

For a given voltage, more current will flow in a larger diameter wire due to the lower resistance. If the power dissipation in the wire becomes too great, the wire will melt.

8. ### odm4286 Thread Starter Active Member

Sep 20, 2009
155
5
Ok I follow you but using the analogy of water...where exactly does the water come from? As far as the lessons I have read on this website explained is that a battery or power source creates potentional difference in electrons and protons in a circuit and its the movement of electrons that creates current or do I have this wrong

9. ### Audioguru New Member

Dec 20, 2007
9,411
896
A resistor in series with a voltage source then the resistor feeds a load resistance. Then the two resistors are a voltage divider. The voltage at the load is reduced because the first resistor reduces the current.

10. ### SgtWookie Expert

Jul 17, 2007
22,183
1,728
We're talking a "closed system" here.

A battery or generator is like a water pump. Wires are sort of like pipes that are already filled with water. It just takes pressure to get the current going.

The movement of electrons through a wire IS current.
It's the pressure (voltage) that causes the movement (current).

11. ### ke5nnt Active Member

Mar 1, 2009
384
15
Voltage is a force, hence, EMF (electromotive force).

Not to confuse you any further, because I know what it's like (trust me), but remember that electron flow is different between solid wire, and stranded.

Apr 20, 2004
15,815
283
13. ### Ratch New Member

Mar 20, 2007
1,068
3
odm4286,

It is a shame that voltage is not described as it really is instead of confusing you with analogies. Read the links below, then ask your question in a clear manner. I will try to answer with respect to the way things really happen in a simple manner.