# Thread: String Trimmer Batteries - same weight charged and empty

1. There are several mechanisms for generating photons. Don;t forget the wave particle duality.

Thermal photons as in BB radiation.

AC electric current in a conductor giving rise rt EM radiation. Antennas.
t
Solid state photo emitters like light emitting diodes and laser diodes.

In all cases there is an energy balaqnce, but it may not seem obvious unless you are familiar with the model and units. The form of the balance changes but energy must alwats add up. No exceptions.

Consider a light emitting diode. To understand the mechanism at the quantum scale you have to first understand electrons, atomic states and bangaps, and photons expressed in electron volts, eV Ev can be converted to joules. The wavelenth of a photon is an expression of photon energy. When a photon is emitted from an LED the energy or wavelength of the photon equals the atomic bandgap voltage in eV. Energy in ev must allays add up going back to the source power supply.

The quantum efficiency of an LED is expressed inphotons per electrons.

You can look up the LED equations for current to photons and the energy transfers.

When a photon at the bandgap voltage of a photodetector an atom adsorbs the photon with an increase in energy of the photon in eV. The quantum efficiency of a detector is electrons per photon.

LOT always applies to energy conversion. In this case energy added to electrons by the power supply to energy added by electrons to an atom to the energy of an emoted photon. Enemy along the chain must add up including heat resulting from inefficiency.

If you believe the current iout of an incandescent bulb will always be lower than what goes in then conservation still applies.

An example is worth 1000 net references.

connect a batty to a bulb with wires. Draw a bubble or thermodynamic boundary around the bulb. Energy in to the bulb or system is current from the battery. Energy out of the system is photons and return current to the battery. It must all add up.

LOT applies to energy and mass crossing a system boundary.

2. Originally Posted by steve_bank
There are several mechanisms for generating photons. Don;t forget the wave particle duality.

Thermal photons as in BB radiation.

AC electric current in a conductor giving rise rt EM radiation. Antennas.
t
Solid state photo emitters like light emitting diodes and laser diodes.

In all cases there is an energy balaqnce, but it may not seem obvious unless you are familiar with the model and units. The form of the balance changes but energy must alwats add up. No exceptions.

Consider a light emitting diode. To understand the mechanism at the quantum scale you have to first understand electrons, atomic states and bangaps, and photons expressed in electron volts, eV Ev can be converted to joules. The wavelenth of a photon is an expression of photon energy. When a photon is emitted from an LED the energy or wavelength of the photon equals the atomic bandgap voltage in eV. Energy in ev must allays add up going back to the source power supply.

The quantum efficiency of an LED is expressed inphotons per electrons.

You can look up the LED equations for current to photons and the energy transfers.

When a photon at the bandgap voltage of a photodetector an atom adsorbs the photon with an increase in energy of the photon in eV. The quantum efficiency of a detector is electrons per photon.

LOT always applies to energy conversion. In this case energy added to electrons by the power supply to energy added by electrons to an atom to the energy of an emoted photon. Enemy along the chain must add up including heat resulting from inefficiency.

If you believe the current iout of an incandescent bulb will always be lower than what goes in then conservation still applies.

An example is worth 1000 net references.

connect a batty to a bulb with wires. Draw a bubble or thermodynamic boundary around the bulb. Energy in to the bulb or system is current from the battery. Energy out of the system is photons and return current to the battery. It must all add up.

LOT applies to energy and mass crossing a system boundary.
So, you're saying my flashlight with the dead battery weighs less than the one with the good battery?

3. Originally Posted by Bronzeage
Originally Posted by steve_bank
There are several mechanisms for generating photons. Don;t forget the wave particle duality.

Thermal photons as in BB radiation.

AC electric current in a conductor giving rise rt EM radiation. Antennas.
t
Solid state photo emitters like light emitting diodes and laser diodes.

In all cases there is an energy balaqnce, but it may not seem obvious unless you are familiar with the model and units. The form of the balance changes but energy must alwats add up. No exceptions.

Consider a light emitting diode. To understand the mechanism at the quantum scale you have to first understand electrons, atomic states and bangaps, and photons expressed in electron volts, eV Ev can be converted to joules. The wavelenth of a photon is an expression of photon energy. When a photon is emitted from an LED the energy or wavelength of the photon equals the atomic bandgap voltage in eV. Energy in ev must allays add up going back to the source power supply.

The quantum efficiency of an LED is expressed inphotons per electrons.

You can look up the LED equations for current to photons and the energy transfers.

When a photon at the bandgap voltage of a photodetector an atom adsorbs the photon with an increase in energy of the photon in eV. The quantum efficiency of a detector is electrons per photon.

LOT always applies to energy conversion. In this case energy added to electrons by the power supply to energy added by electrons to an atom to the energy of an emoted photon. Enemy along the chain must add up including heat resulting from inefficiency.

If you believe the current iout of an incandescent bulb will always be lower than what goes in then conservation still applies.

An example is worth 1000 net references.

connect a batty to a bulb with wires. Draw a bubble or thermodynamic boundary around the bulb. Energy in to the bulb or system is current from the battery. Energy out of the system is photons and return current to the battery. It must all add up.

LOT applies to energy and mass crossing a system boundary.
So, you're saying my flashlight with the dead battery weighs less than the one with the good battery?
What I am saying is I read books and applied thermodynamics. I believe there is no weight loss. In the case of an incandescent bulb the energy to create photons comes from current cresting temperature through the resistance of the bulb.

In the case of an LED I'd have to look the mechanisms involving electrons-holes pairs to be sure , which I am not interested in doing. Haven't looked at it in a long time.

If you search the net I'd bet it has been discussed.

4. Originally Posted by Bronzeage
So, you're saying my flashlight with the dead battery weighs less than the one with the good battery?
I'll say that, yes.

 1.00784 Atomic weight of hydrogen 1.00784 Atomic weight of hydrogen 15.999 Atomic weight of oxygen 18.0147 Atomic weight of 2 H and 1 O. 18.0153 Atomic weight of water 0.0006 How much more water weighs than 2 H and 1 O.

The difference (.0006) is (multiplied by the number of oxygen atoms in your hydrogen/oxygen battery) the difference in weight between your charged and discharged battery.

That same number (.0006 times the number of oxygen atoms involved) multiplied by c squared is the amount of energy (at an impossible 100% efficiency) that you get out of your battery and/or the energy required to recharge it.

It was big news when somebody figured out that, for instance, sodium chloride (NaCl) doesn't weigh the same as sodium (Na) plus chlorine (Cl).

5. Originally Posted by steve_bank
Originally Posted by Bronzeage
Originally Posted by steve_bank
There are several mechanisms for generating photons. Don;t forget the wave particle duality.

Thermal photons as in BB radiation.

AC electric current in a conductor giving rise rt EM radiation. Antennas.
t
Solid state photo emitters like light emitting diodes and laser diodes.

In all cases there is an energy balaqnce, but it may not seem obvious unless you are familiar with the model and units. The form of the balance changes but energy must alwats add up. No exceptions.

Consider a light emitting diode. To understand the mechanism at the quantum scale you have to first understand electrons, atomic states and bangaps, and photons expressed in electron volts, eV Ev can be converted to joules. The wavelenth of a photon is an expression of photon energy. When a photon is emitted from an LED the energy or wavelength of the photon equals the atomic bandgap voltage in eV. Energy in ev must allays add up going back to the source power supply.

The quantum efficiency of an LED is expressed inphotons per electrons.

You can look up the LED equations for current to photons and the energy transfers.

When a photon at the bandgap voltage of a photodetector an atom adsorbs the photon with an increase in energy of the photon in eV. The quantum efficiency of a detector is electrons per photon.

LOT always applies to energy conversion. In this case energy added to electrons by the power supply to energy added by electrons to an atom to the energy of an emoted photon. Enemy along the chain must add up including heat resulting from inefficiency.

If you believe the current iout of an incandescent bulb will always be lower than what goes in then conservation still applies.

An example is worth 1000 net references.

connect a batty to a bulb with wires. Draw a bubble or thermodynamic boundary around the bulb. Energy in to the bulb or system is current from the battery. Energy out of the system is photons and return current to the battery. It must all add up.

LOT applies to energy and mass crossing a system boundary.
So, you're saying my flashlight with the dead battery weighs less than the one with the good battery?
What I am saying is I read books
Apparently not very carefully; Or not the right books.
and applied thermodynamics.
Incorrectly.
I believe there is no weight loss.
Reality doesn't give a shit what you believe.
In the case of an incandescent bulb the energy to create photons comes from current cresting temperature through the resistance of the bulb.
True, but completely irrelevant.

In the case of an LED I'd have to look the mechanisms involving electrons-holes pairs to be sure , which I am not interested in doing. Haven't looked at it in a long time.
As it's not even slightly relevant, I suggest you don't bother.

If you search the net I'd bet it has been discussed.
Doubtless. And by lots of idiots and ignoramuses.

The fact remains that energy and mass are equivalent; And that a battery in a power tool or flashlight is not a closed system.

6. Originally Posted by Wiploc
Originally Posted by Bronzeage
So, you're saying my flashlight with the dead battery weighs less than the one with the good battery?
I'll say that, yes.

 1.00784 Atomic weight of hydrogen 1.00784 Atomic weight of hydrogen 15.999 Atomic weight of oxygen 18.0147 Atomic weight of 2 H and 1 O. 18.0153 Atomic weight of water 0.0006 How much more water weighs than 2 H and 1 O.

The difference (.0006) is (multiplied by the number of oxygen atoms in your hydrogen/oxygen battery) the difference in weight between your charged and discharged battery.
Actually, this is all incorrect because H2O should be lighter than H+H+O. What happened is that you were not careful with isotopes

7. Originally Posted by steve_bank
What I am saying is I read books and applied thermodynamics. I believe there is no weight loss. In the case of an incandescent bulb the energy to create photons comes from current cresting temperature through the resistance of the bulb.

In the case of an LED I'd have to look the mechanisms involving electrons-holes pairs to be sure , which I am not interested in doing. Haven't looked at it in a long time.

If you search the net I'd bet it has been discussed.
E = mc^2. The charged battery contains chemicals with higher energy levels.

8. Originally Posted by Loren Pechtel
Originally Posted by steve_bank
What I am saying is I read books and applied thermodynamics. I believe there is no weight loss. In the case of an incandescent bulb the energy to create photons comes from current cresting temperature through the resistance of the bulb.

In the case of an LED I'd have to look the mechanisms involving electrons-holes pairs to be sure , which I am not interested in doing. Haven't looked at it in a long time.

If you search the net I'd bet it has been discussed.
E = mc^2. The charged battery contains chemicals with higher energy levels.
I don't see where E=mc^2 has anything to do with a battery's potential difference between terminal At least computationally. It never appears in any of my texts on solid state theory. For photo emitters like an LED the theory is in terms of electron, photon, and atomic bandgap energy expressed in eV. Quantum theory.

For an incandescent build it is BB radiation powered by thermal energy. Take a bar of metal and heat it enough with a flame and it will glow in the visible spectrum. In a bulb heat is supplied by reliance heating of the filament.

E=mc^2 is the energy stored in the atomic forces. What gets released in fission by splitting an atom.

A battery creats a volatge potenial that creates a staic electric field acoss a conductor that exerts force on electron.

In an unconnected wire thermal electrons are randomly bouncing around. At a cross section the number of electrons crossing in one direction equal electrons going the other way. This is called charge neutrality. There is no net current in any direction.

Put a battery across the wire and the electric field across the wire creates a net drift in one direction. An electron from the battery does not enter one end of the wire, travel down the wire, and pop out the other end back to the battery. There are conduction animations online.

A good analogy for a battery or any voltage source is a water pump. The water analogy for current is common. You can replce the battery with a generator or transformer and the problem does not change.

Like I said it is a good question, it brings in a lot.

9. Take an ideal gas "battery" and calculate it's weight using STO and you will find out that its mass will depend on temperature and hence internal energy with full accordance with E=mc^2

E=mc^2 is built-in into STO.

10. Originally Posted by steve_bank
Originally Posted by Loren Pechtel
Originally Posted by steve_bank
What I am saying is I read books and applied thermodynamics. I believe there is no weight loss. In the case of an incandescent bulb the energy to create photons comes from current cresting temperature through the resistance of the bulb.

In the case of an LED I'd have to look the mechanisms involving electrons-holes pairs to be sure , which I am not interested in doing. Haven't looked at it in a long time.

If you search the net I'd bet it has been discussed.
E = mc^2. The charged battery contains chemicals with higher energy levels.
I don't see where E=mc^2 has anything to do with a battery's potential difference between terminal At least computationally. It never appears in any of my texts on solid state theory.
... snip ...
.
It doesn't appear in your texts because the mass contributed by the energy difference between a dead battery and a fully charged battery is insignificant (much less than measurement error) for normal concerns. You will also find in texts that if two cars are approaching each other from opposite directions, each traveling a 50MPH, then each will measure the closing speed to be 100MPH. This also is incorrect because of time dilation and Lorentz contraction but the difference from the 100MPH will be so small as to be insignificant.

The differences between Newtonian physics and Einstein only becomes significant for extremely high relative velocities, extremely great masses, and extremely high energy differences... but the differences are still there in our human scale existence, just not sufficiently noticeable to be of any importance. For human scale events, you would have to go out quite a few decimal places in your calculations to see the difference.

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