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I have a question? #126955
03/21/01 07:08 AM
03/21/01 07:08 AM
O
old Appy  Offline OP
Member
Joined: Mar 2001
Posts: 118
Auckland, New Zealand
In a circuit does the current remain unchanged? ie how is i possible to remove an electron or loose one. Does that mean the current entering a circuit is equal to the current leaving a circuit.
I can understand how the Voltage or EMF can lower due to resistance. But am a little confused about the relationship current and voltage loss

Tools for Electricians:
Re: I have a question? #126956
03/21/01 07:31 AM
03/21/01 07:31 AM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,360
http://www.sciencejoywagon.com/physicszone/lesson/07electr/kirchoff/index.html

[Linked Image]

Appy, these are just basics, poke around here and find some of Scott's responses...

[Linked Image]

Re: I have a question? #126957
03/21/01 09:48 AM
03/21/01 09:48 AM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,901
NY, USA
Sparky,

Good Stuff!

[Linked Image]
Bill

Re: I have a question? #126958
03/21/01 03:40 PM
03/21/01 03:40 PM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,901
NY, USA
Old Appy,

I'm a little unclear on that also. I'm wondering where the Energy comes from that is released as Heat or Light etc. as current passes through it. It seems like something should be depleted somewhere. I don't think electrons get 'lost' but they may give up their energy and stop flowing. Or, what I'm thinking is that some of them may pass their energy, say to electrons in a Lightbulb filament which in turn give off Light and Heat.

Less Electrons flowing means lower voltage. (I = E/R) So in the case of a set amount of pressure (voltage) as in a Battery, Current and Voltage will eventually drop off.

Anyone, Does this seem right?

Be kind.... [Linked Image]

Bill

Re: I have a question? #126959
03/21/01 05:35 PM
03/21/01 05:35 PM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,360
well....i've read Scott's responses in the thread below
" an anology of electrical power transfer" a number of times.

i'm starting to realize that a lot of our trade is somewhat programed, spoon fed, or simply given the ten cent tour of theory.

i suppose we need not major in the physics of electricty to do our trade, but it certainly evokes more thought to have a grasp on such things during any given installation.

i can only answer a Q with a Q here.

if energy can't be destroyed, and a light fixtures byproduct is heat, would the tranfer to heat be "loosing" electrons?

Does a more efficent light give more electrons to light that to heat?

[Linked Image]

If we hook up a mile of wire to your battery, we will see a difference at either end, all due to R factor?

Re: I have a question? #126960
03/21/01 07:05 PM
03/21/01 07:05 PM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,901
NY, USA
Sparky,

I'm out on a limb with a chainsaw here! [Linked Image]
Keep in mind this is in 'Bills' World' and may prove no resemblance to things in the real world.

Once upon a time...

I would say that what you are losing is Free electrons from your flow. Those are the ones that have the energy to jump from atom to atom as part of your current flow. They're either giving up their 'juice' to the atoms in the filament or decide to leave your group and join the 'Resistance' (I didn't plan that it just happened [Linked Image])

So these Electrons in the Filament are stirring things up and the result of the increased activity is Heat. The amount of light emitted and its' color depend on the temperature of the Filament.

What do you think? [Linked Image]

Bill

Re: I have a question? #126961
03/21/01 09:07 PM
03/21/01 09:07 PM
S
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,360
well my volt-tic's gotta be catchin' something so i guess i'd go along with that.

filament temp, or heat vs. visible spectrum is interesting, we do use that K # system, it might be kelvin....

so i guess i'm on the limb with ya Bill, i got a feelin' an EE's gonna crank up the chipper machine though...

[Linked Image]

Re: I have a question? #126962
03/21/01 10:30 PM
03/21/01 10:30 PM
Bill Addiss  Offline
Member
Joined: Oct 2000
Posts: 3,901
NY, USA
Sparky,

That's right, Color temperature is measured in degrees Kelvin, (Black Body Temperature I think it's called)

I'm waitin for the Chipper...

[Linked Image]
Bill

Re: I have a question? #126963
03/22/01 07:03 AM
03/22/01 07:03 AM
O
old Appy  Offline OP
Member
Joined: Mar 2001
Posts: 118
Auckland, New Zealand
Althought Kirchhoffs Current Law states "Electrical charge is neither created nor destroyed in ordinary circuit operation..."
This i take too mean Electrons Flow ?

Re: I have a question? #126964
03/23/01 09:15 PM
03/23/01 09:15 PM
S
Steve T  Offline
Member
Joined: Feb 2001
Posts: 306
Oak Park, IL, USA
The energy to move the electrons is transfered. The electrons moving are just a transfer of that energy.

Imagine if you will, you could move a magnet with your hand and arm across a coil of wire to generate voltage and current flow. The energy comes from the food you ate to make your hand and arm move not the electrons of the conductor.

Or, you are in bumper to bumper traffic(literally) and the last car rams into the car in front of it. The gas being burned made the car move and cause one car after another to "move". The movement of the first car in line will equal the energy of the gas being burned. Even if the brakes are on (resistance) the heat produced by brake pads etc. will be an equal transfer of power. Power is not created or destroyed.

I think this is a simplistic explanation but gets the point across about electrons being "lost"

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