Electrical Resistance of Water

[GoldDigger]

...
(Glossing over lots of details that I don't fully understand. You too can be a quantum mechanic!)

My college theoretical physics prof had a sign on his door:

Quantum Mechanic At Work.
Quanta Repaired While You Wait.

 

[mbrooke]

No. Well below semiconductor conductivity.


Sent from my iPhone using Tapatalk

How is semi conductor defined?

 

[winnie]

I think the distinction is somewhat arbitrary but depends upon bandgap value.

No bandgap means a conductor. Bandgap of 1eV or so means semiconductor, 9eV or more means insulator. Bandgap of 2-4 eV is a 'wide bandgap' semiconductor.

See http://www.optique-ingenieur.org/en/courses/OPI_ang_M05_C02/co/Contenu_02.html

Jon

 

[mbrooke]

I think the distinction is somewhat arbitrary but depends upon bandgap value.

No bandgap means a conductor. Bandgap of 1eV or so means semiconductor, 9eV or more means insulator. Bandgap of 2-4 eV is a 'wide bandgap' semiconductor.

See http://www.optique-ingenieur.org/en/courses/OPI_ang_M05_C02/co/Contenu_02.html

Jon

Was that site written by the same member ingenieur who posted here?

 

[FionaZuppa]

I'd love to learn more about this. I always understood this disassociation to be an equilibrium process, meaning that if you had H2O present then you would have the ions present and that Hydrogen was always jumping around so that you could never be sure which was H2O and which was the ions.

Jon

If they are polarized ions, the will move in an electric field, right?

 

[winnie]

If they are polarized ions, the will move in an electric field, right?

Yes, I expect that if you apply an electric field that the H3O+ will move one way and the HO- will move the other way.

But then I expect that if you have a strong enough field to leave pure water in the middle that it would disassociate and generate more H3O+ HO- pairs.

The electric field might move these newly created ions, but eventually enough ions will have moved as to cancel out the electric field, so eventually I'd expect you to end up with a high concentration of H3O+ on one side, HO- on the other side, and the normal mix of H3O+ and HO- in the middle (all in lots of surrounding H2O).

So I figure I am missing some detail.

Thanks
Jon

 

[Russs57]

You measure the conductivity of water. One standard is 1/micro ohms per cm (called umhos). The other is microsiemens. Consider them the same for now.

A handy way to remember conductivity to resistivity is one umhos/cm = 1,000,000 ohms/cm = 10,000 ohms/m.

Tap water varies a good bit depending on source. I'd say maybe 50 - 500 umhos. Tap water in my area is around 150-200 umhos.

 

[RumRunner]

I'm a tad weak on quantum physics, but then most garden variety sparks such as i are rarely exposed to it Jon

such a shame too , we'd really have a handle on the rationale of our trade ....

~RJ~

Quantum Mechanics (or quantum physics)-- as regards application to the above mentioned topic is like driving a thumb tack using a 16-pound sledge hammer.
Even notable theoretical physicists like Feynman was skeptical on how it could apply to the accepted theories pioneered by Newtonian Law of Motion.

In the end however, he capitulated that he doesn’t know much about Quantum Mechanics (also called quantum physics)
Albert Einstein was once quoted saying--that his theory of relativity as represented in his equation:
E=MC squared would run in conflict with this “modern” branch of Theoretical Physics.

Einstein posits that if energy is released in one sudden burst --in one intentional event--as in the atom bomb (s) that claimed almost 75,000 souls—was a one-time event the gives way it’s full potential.

Quantum mechanics--which studies are carried out by the Max Planck Institute of Advanced Studies of Modern Physics-- are an ongoing research. So it’s hard to say that “it’s a done deal”.
I visited one institute of these studies in Berlin about three years ago. Most institutes are in Germany. . . but there is one in Jupiter, Florida and I believe another one is in the Netherlands.

I have to admit that for anyone (including myself) to fully understand Quantum Mechanics --is to fully understand the traditional “orbital” energy--inherent in the potential of atoms/electrons--that orbit a nucleus-- as opposed to Quantum Mechanics’ position that claims--that energy is released in “waves” --something in the form of wave forms.

The energy carried in waves is called quanta.

To know the difference between the two (Classical Physics and Quantum Physics) is essential to even get started.

 

[gadfly56]

Quantum Mechanics (or quantum physics)-- as regards application to the above mentioned topic is like driving a thumb tack using a 16-pound sledge hammer.
Even notable theoretical physicists like Feynman was skeptical on how it could apply to the accepted theories pioneered by Newtonian Law of Motion.

In the end however, he capitulated that he doesn’t know much about Quantum Mechanics (also called quantum physics)
Albert Einstein was once quoted saying--that his theory of relativity as represented in his equation:
E=MC squared would run in conflict with this “modern” branch of Theoretical Physics.

Einstein posits that if energy is released in one sudden burst --in one intentional event--as in the atom bomb (s) that claimed almost 75,000 souls—was a one-time event the gives way it’s full potential.

Quantum mechanics--which studies are carried out by the Max Planck Institute of Advanced Studies of Modern Physics-- are an ongoing research. So it’s hard to say that “it’s a done deal”.
I visited one institute of these studies in Berlin about three years ago. Most institutes are in Germany. . . but there is one in Jupiter, Florida and I believe another one is in the Netherlands.

I have to admit that for anyone (including myself) to fully understand Quantum Mechanics --is to fully understand the traditional “orbital” energy--inherent in the potential of atoms/electrons--that orbit a nucleus-- as opposed to Quantum Mechanics’ position that claims--that energy is released in “waves” --something in the form of wave forms.

The energy carried in waves is called quanta.

To know the difference between the two (Classical Physics and Quantum Physics) is essential to even get started.

The slit experiment is the classic illustration of the wave nature of light. The fact that the solar wind exerts enough pressure to allow the use of solar sails reveals light's particle nature.

 

[GoldDigger]

You measure the conductivity of water. One standard is 1/micro ohms per cm (called umhos). The other is microsiemens. Consider them the same for now.

A handy way to remember conductivity to resistivity is one umhos/cm = 1,000,000 ohms/cm = 10,000 ohms/m.

Tap water varies a good bit depending on source. I'd say maybe 50 - 500 umhos. Tap water in my area is around 150-200 umhos.

You are describing the units in a somewhat confusing (or incorrect) way.
Basics:
1. 1 Siemens (conductivity of a discrete lumped impedance) == 1/Ohm == 1 mho in old units
2. Bulk resistivity of a material has units of Ohm-centimeters or Ohm-meters. A funny looking unit, but dimensionally correct.
3. So, the units for bulk conductivity has the units 1/resistivity == Siemens/cm or Siemens/meter == (1/Ohms)/cm or (1/Ohms/meter)

 

[mbrooke]

'Ground state' is the energy level of an atom, molecule, or larger assemblage when it is at lowest energy; in this case talking about electrons in orbitals.

Think about ordinary hydrogen. 1 electron, 1 proton. Apply enough energy and you can rip that electron completely away from the proton. The amount of energy needed to rip that electron away depends on how much energy it had to start with. But there is a lowest energy orbital that the electron can be in, called the ground state.

As more protons and electrons are added to an atom, the different possible orbitals get filled up in order of lowest energy to highest. In general the electron in the highest energy state is the one available to move around. (Glossing over lots of details that I don't fully understand. You too can be a quantum mechanic!)

In a dense material like a solid (as opposed to a gas) the orbitals of the individual atoms blend together, and you should really think in terms of electron energy bands.

In a metal, the 'highest occupied energy band' is only partially filled. This means that only a smidge of energy is needed for an electron to move into a free state and move around.

In an insulator, the 'highest occupied energy band' is completely filled. For an electron to move around a large amount of energy needs to be added to rip it from the occupied band into an energy band where it can move around. Apply enough energy (say in the form of an intense electric field, or bombard things with high energy particles) and yes, you will get current flow. I don't know if porcelain will ever 'look like copper', because the energy needed for getting electrons to flow might be so much that you've vaporized the material and now have current flowing through an arc, but apply enough energy and you will have conduction.

In a semiconductor the 'highest occupied energy band' is completely filled, but an un-occupied band is available that isn't much higher in energy. This means that things like the random thermal energy of the electrons in the material is enough for some of them to be in an unoccupied band where they can move.

-Jon
In a metal 'open' electron states are available right next to occupied electrons states, so the electrons are really really free to move.

In a semiconductor, there are well defined energy ba

So wait a minute--- it takes energy to move energy? Where does the energy come from that holds electrons in orbit? Is this why we can't get absolute zero?

 

[winnie]

So wait a minute--- it takes energy to move energy? Where does the energy come from that holds electrons in orbit? Is this why we can't get absolute zero?

It takes energy to promote electrons to the conduction band in a semiconductor. In semiconductors the conductivity goes down as they get colder.

Where the energy of electrons in their orbitals comes from is well above my pay grade Protons attract electrons, so if you had a separated proton and electron they would pull together, but why they attract in the first place I cannot answer.

The inability to get absolute zero is a different issue; essentially having to do with how heat pumps work. It would take infinite energy to pump heat away from absolute zero, and I am not good enough with thermodynamics to explain it

-Jon

 

[mbrooke]

It takes energy to promote electrons to the conduction band in a semiconductor. In semiconductors the conductivity goes down as they get colder.

Where the energy of electrons in their orbitals comes from is well above my pay grade Protons attract electrons, so if you had a separated proton and electron they would pull together, but why they attract in the first place I cannot answer.

The inability to get absolute zero is a different issue; essentially having to do with how heat pumps work. It would take infinite energy to pump heat away from absolute zero, and I am not good enough with thermodynamics to explain it

-Jon

Thanks- to fascinating.

Anyone know why protons attract electrons? And why neutrons do nothing in essence? Does matter exist or is it just numbers trying to solve to zero?

 

[FionaZuppa]

Thanks- to fascinating.

Anyone know why protons attract electrons? And why neutrons do nothing in essence? Does matter exist or is it just numbers trying to solve to zero?

??
Coulomb's Law explains the how, there is no good explanantion for why. Most often observations are explained in terns of how, and usually accompanied by some physics proven with mathematical equations. In general, many things are "it just is". Like why does every galaxy have a blackhole in it? Dunno, it just is.

 

[mbrooke]

??
Coulomb's Law explains the how, there is no good explanantion for why. Most often observations are explained in terns of how, and usually accompanied by some physics proven with mathematical equations. In general, many things are "it just is". Like why does every galaxy have a blackhole in it? Dunno, it just is.

Blackhole was used to form the galaxy's spiral...? It stop feeding eventually?

 

[RumRunner]

The slit experiment is the classic illustration of the wave nature of light. The fact that the solar wind exerts enough pressure to allow the use of solar sails reveals light's particle nature.

That’s where the two Physics… the Classical Physics and Quantum Mechanics intersect--to a more discernible aspect on how--we “regular joes” get a grasp at least vernacularly--that light does have particle(s) that enable science to assert that pressure can be exerted to light in order make it useful . . . as in your slit experiment. Good thinking.
Pressure applied by solar wind could provide propulsion for vehicle to enable humans for an interstellar travel in the cosmos.

When Isaac Newton was experimenting on the Laws of Gravity. . . he found out that objects that have mass pull at each other through the phenomenon called gravitational force.
He demonstrated his finding when he dropped an apple. The apple landed on earth.
He also found out that gravitational force is proportional to MASS. The apple is smaller than Earth and therefore it fell to earth.. . . attracted by the gravitational force of massive planet Earth.

And then Albert Einstein came up with his Theory of Relativity. In it, he asserts that light does not possess MASS. . . . and therefore not affected by gravitational force.
If light is beamed on a plane (flat parallel surface) it travels in a straight line. OK with Newton’s Theory so far.

As Einstein’s further studies go forward. . . these assertions (he hypothesized) only apply here on Earth.
When you apply the theory on those planets that inhabit the universe, this straight light trajectory of a light beam. . . Newton’s theory failed.

To demonstrate this failure, think of a space with a sheet of rubber that is stretched to a perfect flat surface.
Put a heavy object on it like a ball and it will make a dimple that conforms the shape of the ball.

Think of this rubber sheet in outer space where an object (a planet) makes a dimple--deep enough you can’t see the bottom.
According to Einstein-- this dimple can have an effect if you project a beam of light across it.

If the rim of the dimple is abrupt --the light which follow the surface--to a point that light will never make it out to the surface.

Light is a form of energy that get sucked into a dark abyss that is called black hole.

There is more to interaction between forces as defined by Quantum Physics --and other disciplines that highlight our accepted knowledge from Einstein, Newton and others--and important studies by the Max Planck Institute regarding Quantum Physics.

So, this failure of Newton’s law about the massless light--and the consequence of not being affected by gravity is debunked by Einstein’s Theory of Relativity.

It asserts that a beam of light can bend.

 

[Russs57]

• Matter tells spacetime how to curve.
• Curved spacetime tells matter how to move.

 

[mbrooke]

If light has no mass to it, then how does it go around heavy objects?

 

[GoldDigger]

If light has no mass to it, then how does it go around heavy objects?

Light has mass, just no rest mass. If you stop a photon it goes away.

 

[mbrooke]

Light has mass, just no rest mass. If you stop a photon it goes away.

Turning into heat, right?