Amps, Voltage etc

[AnthonyFWilson]

Hi,

I'd like to know if anyone knows any good sources to help understand amps, voltage etc better. The teachers at college haven't got in on the subject just yet. I don't yet fully understand the breakers and why different amps are needed for different circuits.

Thanks,
Anthony.

 

[Sintra]

Amps: Electrical flow rate.
Imagine electricity (charge) is like water.
The amount of Amps represents the amount of charge flowing past a point in a particular time. In fact the unit of the Ampere is 1 Coulomb of charge flowing past a point in 1 second of time.




Volts: Electrical pressure (or potential).
There are a few of ways of looking at potential difference (volts). 1: it's the pressure which causes current to flow. 2: it represents the amount of energy posessed, or liberated by each Coulomb of charge. 3: it's the electrical height through which charge falls.




Ohms: Electrical resistance.
Ohms resist electrical current. So for the same voltage, an increased resistance will cause a reduction in current.




Cobble these together and you get the famous "Ohms Law"




V=I x R
Where R is the resistance
I is the current through the resistance and
V is the voltage across the resistance.




Watts: This is the unit of power. In specifically electrical terms, it is the amount of energy converted by an electrical circuit.
Earlier I mentioned that Voltage represents the amount of energy posessed by each Coulomb of charge. This is where it comes in.




Remember that Power = Energy / Time.
So Voltage = Energy / Coulomb
and we know that Amps = Coulombs / Time




So we can tie power into ohms law.




Voltage = Power x Time / Amps x Time.
The "Times" cancel, and it re-arranges to give
Power = Volts x Amps.




This really is the top an bottom of simple electrical circuits.




An example:
Your kettle is rated at 2.3kW (2300W) and 230V (RMS)
The current it will draw from the supply can be calculated thus:




2300W = 230V x 10A

 

[Marvo]

For the very basic electrical theory you should check out these books. They're very well written and distributed under the DSL license so they're free. Lessons In Electric Circuits

I would start with volume II which is AC theory if I were you.

 

[snowhead]

Voltage,, The incentive for electricity to flow.

Current,, The flow of electricity taking place.

Resistance,, The disincentive for electricity to flow.

Watts result when the current gets the incentive to flow.

 

[telectrix]

another analogy to water is that the smaller the cross sectional area of a conductor, the higher the resistance, similar to a smaller water pipe passing water slower than a large pipe.

 

[Stroppy]

V=I x R
Where R is the resistance
I is the current through the resistance and
V is the voltage across the resistance.

You may wonder why on earth I is used to represent the current, instead of A for Amps, or maybe C for current. Well apparently (and this may not be true as I read it in the internet), current flow used to be knows as "Intensity" in the early days of electrical experimenting.

 

[ayjay]

thats a good way of equating electricity telectrix ,i explain it in that way too

 

[ayjay]

stroppy-in australia the live is known as "active" or as the pronouce it"ictive"
just thought i,d throw that in