how to think current, voltage, &#8230;

Discussion in 'Electronic Basics' started by zooeb, Jan 4, 2005.

1. zooebGuest

I think electrical matter is very hard to grab, because current,
voltage & C. are invisible. Even after years of practice I have some
doubts about it. Here they are (someone): 1)voltage mean how many
Newton every Coulomb is able to "put out". But, what is the difference
between 1 Coulomb that has 100 Newton (for example) in it (ready to
put out) and 1 Coulomb that has 200 Newton (for example) in it (ready
to put out); in particolar what does it change in phase of generation
of voltage? Why the second quantity of charge has more power?
2)imagine a voltage generator empty (I mean it generate voltage, but
there is no load attached to) so that current is zero, then imagine I
prolong one of the two terminal, connecting to it a piece of wire of
relevant lenght regard to the lenght of generator terminal. Just
connected it; is there an electric current (even for a little while)
which flow into the wire? I think yes, there is a current, because
electric charges concentred in the terminal have the possibility to
expand along the new wire. 3)OK, now imagine always the same situation
of point number 2; and imagine of disconnecting the wire: all the
electric charge which there were in it remains or falls down? 4) All
generators I know behave similar to voltage generator: does it exist a
similar current generator without electronic device (transistor,
diode, ...) in it? 5) I'm thinking a way of imaging current, voltage,
resistance, impedence, capacitance, inductance, electric field,
magnetic field, electromagnetic field using duality with other
matters. The easiest way is to think voltage like water pressure, but
using hydraulic duality I think you are not able to introduce the
concept of impedence, capacitance, electromagnetic fields, .... Have
you a piece of advice about it? 6) Thank you very much, bye.

2. Andrew HolmeGuest

Here's my take on this: You have a voltage source. You extend (lengthen)
the terminals. The extension is a capacitor. You are connecting a
capacitor across a voltage source. Charge flows onto the capacitor.
Finally, you remove the extension. This is like removing one of the plates
of a capacitor. If you could physically do this, without discharging it, I
think the plate (wire) would retain its electrostatic charge.

3. Dan DunphyGuest

Top post.
This has nothing to do with newtons, a physical unit of force.

Energy E = 1/2 *C*V^2 . In the MKS system "joules".
A joule is 1 watt-second