Noise voltage

[gar]

190122-2458 EST

If you take any resistor that is not at absolute zero, then there is an open circuit voltage across that resistor related to temperature, and other factors.

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[mopowr steve]

Are you saying that you read a voltage across a resistor just sitting there? That is induced by some outside force such as radio transmission?

 

[GoldDigger]

Are you saying that you read a voltage across a resistor just sitting there? That is induced by some outside force such as radio transmission?

He is saying that there is a voltage which exists simply because the charge carriers (typically electrons) have a distribution of energies and directions determined by the resistor temperature and that the random motion of these charge carriers in the absence of any external electrical or magnetic field will cause a voltage to appear between the ends of the resistor. This voltage will average zero (no DC component) and will consist of a broad spectrum of frequency components.
You may be more familiar with the concept of thermal noise generation associated with a diode.
You can probably use the analogy of fluctuations in air pressure which correspond to some or all of the air molecules in a room deciding to go in the same direction at the same time. :?

 

[gar]

190123-0819 EST

See
https://en.wikipedia.org/wiki/Johnson–Nyquist_noise

If you take an AM broadcast band radio inside a screen room, a room that is shielded to essentially eliminate radio signals from outside the room getting into the room, and power the radio, then you will hear a hiss. This hiss is noise from the input resistance of the set and its input amplifier. Beyond this first amplifier the noise from subsequent circuits is masked by the amplified noise of the first amplifier.

All sensitive meters and instruments are affected by thermal noise. When you get down to signal levels like those in straingage transducers, then resolution of small forces relative to full scale becomes dependent upon this noise.

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[__dan]

Well if you are saying the resistor can have a random instantaneous polarization across it that is always changing, I could see that. With enough amplification you could get noise, so an observable effect. Extreme amplification will give you noise.

If you want to say the electron is moving, in the condition of the conductor is open circuit and not externally driven, does it?, is the electron moving.

If the electron moves, it would radiate by Maxwell's laws. Radiation would be open loop so it is giving off and receiving energy from beyond solely itself. But saying a conductor (resistor) is open circuit is like saying the electron is not externally driven. It is not a magic show with a hidden power source and load combination.

Also there is no amplifier in your problem statement, so, since this is not observable to be tested, you would look it see if your premise is logically sound.

At this point you may have to say the electron is either: 1. not moving (because it would radiate and give off energy that it has to instantaneously replace from some other source), 2. moving in a way that does not radiate (but violates Maxwell's laws), 3. may move in way that does not radiate and complies with Maxwell's laws (Dr Randall Mills), 4. you don't know if the electron moves or not and don't care to inquire (because in the underlying model of the electron, the electron has a probability of being found in the statistical distribution, but it wound have to move from one point in that distribution to another without moving).

The statistical point charge model of the electron is not logically sound when held to compliance with Maxwell's laws.

If the resistor has an instantaneous voltage potential across it, this implies an unequal electron distribution, which would imply the electrons are moving in the field to restore equilibrium.

So, does the electron move, or moves in a way that does not radiate, or does radiate but instantaneously gets its energy loss replaced, or does not move but only has a statistical probability of being found in the charge distribution, or Mills theory.

 

[__dan]

In your link the resistor is modelled as a perfect resistor with a series thermal noise voltage source or with a parallel thermal noise current source. The model show a noise current flow through the resistor under the condition it is not externally driven and is *at* equilibrium.

https://en.wikipedia.org/wiki/Johnson–Nyquist_noise

This would imply a resistor conversion of that power flow to heat and an aggregating increase in temp. The model shows a self heating resistor.

Unless it is also instantaneously and equally self cooling, the model is showing an over unity device.

Alternately, the model may have some logical flaw in its premises that may be discovered and discarded.

 

[GoldDigger]

In your link the resistor is modelled as a perfect resistor with a series thermal noise voltage source or with a parallel thermal noise current source. The model show a noise current flow through the resistor under the condition it is not externally driven and is *at* equilibrium.

https://en.wikipedia.org/wiki/Johnson–Nyquist_noise

This would imply a resistor conversion of that power flow to heat and an aggregating increase in temp. The model shows a self heating resistor.

Unless it is also instantaneously and equally self cooling, the model is showing an over unity device.

Alternately, the model may have some logical flaw in its premises that may be discovered and discarded.

What you are leaving out is that the resistor is at a specific fixed temperature. That means that it is in thermal equilibrium with a infinite heat source/sink at that temperature. Which in turn means that the resistor can gain thermal energy as needed to make up for energy lost to radiation from electron acceleration.
Looking at the broad picture, the entire system (resistor and heat sink) is in fact slowly losing energy to EM radiation (photons) into the cold of space. Any amplification of the noise signal gets its energy from the power supply of the amplifier.
One of the things that led to the Big Bang theory is the measurable, non-zero, radiation temperature of the universe, as seen in cosmic microwave radiation.

 

[__dan]

Yes the electron is coupled to the ambient by EM. Each electron 'notices' what all the surrounding electrons are doing. It's how we communicate with Mars. Electrons are moved around in the transmitting antenna and every other electron in the universe 'notices'.

Thermal radiation is EM at some point along with conduction, convection.

In the model, the noise source is shown as something beginning or arriving internally in the resistor rather than an externally driven substance that the electron is coupled to. The model's series voltage source or parallel current source is not labelled as 'externally, the ambient' that the electron is coupled to. The source is labeled as a structure internal to the resistor.

In the electron's stable bound state, if the underlying electron model were always loosing energy to radiation from movement of the electron in its stable bound state, (say H, one proton with one electron), this would imply the instability of H, or proton destruction. It would imply the bound state is not stable over the long term as it looses energy in the aggregate and changes form, ultimately to heat.

If this were so it would have happened already and the universe would be a no stable bound state gas cloud, having given up its electron binding energy to heat as radiation to the ambient. This is not what is observed. The stability over the long term and non radiation of H is observed.

 

[GoldDigger]

Yes the electron is coupled to the ambient by EM. Each electron 'notices' what all the surrounding electrons are doing. It's how we communicate with Mars. Electrons are moved around in the transmitting antenna and every other electron in the universe 'notices'.

Thermal radiation is EM at some point along with conduction, convection.

In the model, the noise source is shown as something beginning or arriving internally in the resistor rather than an externally driven substance that the electron is coupled to. The model's series voltage source or parallel current source is not labelled as 'externally, the ambient' that the electron is coupled to. The source is labeled as a structure internal to the resistor.

In the electron's stable bound state, if the underlying electron model were always loosing energy to radiation from movement of the electron in its stable bound state, (say H, one proton with one electron), this would imply the instability of H, or proton destruction. It would imply the bound state is not stable over the long term as it looses energy in the aggregate and changes form, ultimately to heat.

If this were so it would have happened already and the universe would be a no stable bound state gas cloud, having given up its electron binding energy to heat as radiation to the ambient. This is not what is observed. The stability over the long term and non radiation of H is observed.

Presumably Nyquist noise is present only with a conducting medium like a metal or a resistor substrate. H and H₂ are stable and do not emit noise radiation because they have no free electrons. There has to be a conduction band or else dipole structure that can be polarized, as in the dielectric of a capacitor.