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

1. Originally Posted by steve_bank
wiploc

In a photo emitter quantum efficiency photons per electron. In a photo detector it is reverse.

If there is a mass change then heating a metal bar increasing thermal radiation means the bar weighs less. If that is true then as the bar is cooled back to equilibrium it regains weight?
You have it ass-backwards.

When you heat up that bar you are adding energy--the atoms are moving faster, m' = m / (1 - v2/c2). The mass goes up. As the energy radiates away it cools, the atoms slow, the weight goes down.

2. Originally Posted by Loren Pechtel
Originally Posted by steve_bank
wiploc

In a photo emitter quantum efficiency photons per electron. In a photo detector it is reverse.

If there is a mass change then heating a metal bar increasing thermal radiation means the bar weighs less. If that is true then as the bar is cooled back to equilibrium it regains weight?
You have it ass-backwards.

When you heat up that bar you are adding energy--the atoms are moving faster, m' = m / (1 - v2/c2). The mass goes up. As the energy radiates away it cools, the atoms slow, the weight goes down.
That's always been my understanding, that a hot iron is more massive than a cold iron.

It makes sense from a relativistic perspective as well. Mass is motion, more motion equates with more mass. Heat is motion, as are all forms of energy. If things are moving faster, as they are with a hot iron, you will have more mass.

3. wiploc

You are making my case. Heat is the energy that powers the photon.

Energy in energy out with losses in the energy conversion.

In an incandescent bulb the heat is supplied by resistive heating, i^2*R.

In an LED that is not the case. I'd have to look it up.

Photons are EM radiation, the wave particle duality. In free space the propagation is orthogonal electric and magnetic oscillating fields. Photons are the energy carriers. For a given EMR power in watts there are a specific number of photons.

Clarifying, I do care. I do not care to exchange with those who argue from scifi and when called on it resort to ad homs.

You and I are having a reasonable conversation.

4. Originally Posted by steve_bank
wiploc

You are making my case. Heat is the energy that powers the photon.

Energy in energy out with losses in the energy conversion.

In an incandescent bulb the heat is supplied by resistive heating, i^2*R.

In an LED that is not the case. I'd have to look it up.

Photons are EM radiation, the wave particle duality. In free space the propagation is orthogonal electric and magnetic oscillating fields. Photons are the energy carriers. For a given EMR power in watts there are a specific number of photons.

Clarifying, I do care. I do not care to exchange with those who argue from scifi and when called on it resort to ad homs.

You and I are having a reasonable conversation.
E=mc2 isn't scifi.

5. Originally Posted by steve_bank
You are making my case.
On the contrary.

Heat is the energy that powers the photon.
Facepalm? Absent context, that seems an outrageous claim.

Energy in energy out with losses in the energy conversion.
Again, I suspect that I'm failing to understand due to lack of context.

Take your burning paper in a sealed glass box. Energy comes out without being matched by energy going in.

In an incandescent bulb the heat is supplied by resistive heating, i^2*R.

In an LED that is not the case. I'd have to look it up.

Photons are EM radiation, the wave particle duality. In free space the propagation is orthogonal electric and magnetic oscillating fields. Photons are the energy carriers. For a given EMR power in watts there are a specific number of photons.
This part is above my pay grade.

Clarifying, I do care. I do not care to exchange with those who argue from scifi and when called on it resort to ad homs.

You and I are having a reasonable conversation.
Cool, thanks.

It looks like the question of a photon having momentum but no mass is an active problem.

If I read the link right in the theory part of the mass travels with the photon. That I can accept. The queswtion I would have for say a laser diode operating continuously the mass loss would be continuous with no restoration.

Beyond that the theory beyond my depth.

7. Originally Posted by steve_bank

It looks like the question of a photon having momentum but no mass is an active problem.

If I read the link right in the theory part of the mass travels with the photon. That I can accept. The queswtion I would have for say a laser diode operating continuously the mass loss would be continuous with no restoration.

Beyond that the theory beyond my depth.
The energy in the laser beam comes from the electrical power applied not from the mass of the diode. - - electrical energy converted to light energy.

Burning paper involves a very different process though it is still energy converting to a different form. There is no electrical energy applied to the burning paper. The energy (heat and light) that radiates from burning paper comes from chemical energy which involves the energy difference (mass difference) between free atoms and those atoms when combined into a molecule.

8. Originally Posted by skepticalbip
Originally Posted by steve_bank

It looks like the question of a photon having momentum but no mass is an active problem.

If I read the link right in the theory part of the mass travels with the photon. That I can accept. The queswtion I would have for say a laser diode operating continuously the mass loss would be continuous with no restoration.

Beyond that the theory beyond my depth.
The energy in the laser beam comes from the electrical power applied not from the mass of the diode. - - electrical energy converted to light energy.

Burning paper involves a very different process though it is still energy converting to a different form. There is no electrical energy applied to the burning paper. The energy (heat and light) that radiates from burning paper comes from chemical energy which involves the energy difference (mass difference) between free atoms and those atoms when combined into a molecule.
Sure, but electricity is just an intermediary in that case - the chemical energy comes from the fuel burned in the power plant that generates the electricity (typically carbon [coal], methane [gas], or higher alkanes [oil]).

Most electricity worldwide is still made by burning coal, with gas catching up fast. Nuclear power is only a few percent, and the intermittent renewables (wind and solar) are a drop in the ocean. The renewables sector is still dominated by hydropower, with biofuels second, wind a distant third, and solar barely registering.

9. Originally Posted by skepticalbip
Originally Posted by steve_bank

It looks like the question of a photon having momentum but no mass is an active problem.

If I read the link right in the theory part of the mass travels with the photon. That I can accept. The queswtion I would have for say a laser diode operating continuously the mass loss would be continuous with no restoration.

Beyond that the theory beyond my depth.
The energy in the laser beam comes from the electrical power applied not from the mass of the diode. - - electrical energy converted to light energy.

Burning paper involves a very different process though it is still energy converting to a different form. There is no electrical energy applied to the burning paper. The energy (heat and light) that radiates from burning paper comes from chemical energy which involves the energy difference (mass difference) between free atoms and those atoms when combined into a molecule.
Agree energy comes from the mains. Conservation of energy holds. The problem is current theory says a photon has a measurable momentum but no mass. I objected to a solution involving direct energy mass conversion in the atom. The link indicates a possible solution with mass being somehow attached to the photon. I do not have the physics to talk to it off the top of my head.

10. Originally Posted by steve_bank
Originally Posted by skepticalbip
Originally Posted by steve_bank

It looks like the question of a photon having momentum but no mass is an active problem.

If I read the link right in the theory part of the mass travels with the photon. That I can accept. The queswtion I would have for say a laser diode operating continuously the mass loss would be continuous with no restoration.

Beyond that the theory beyond my depth.
The energy in the laser beam comes from the electrical power applied not from the mass of the diode. - - electrical energy converted to light energy.

Burning paper involves a very different process though it is still energy converting to a different form. There is no electrical energy applied to the burning paper. The energy (heat and light) that radiates from burning paper comes from chemical energy which involves the energy difference (mass difference) between free atoms and those atoms when combined into a molecule.
Agree energy comes from the mains. Conservation of energy holds. The problem is current theory says a photon has a measurable momentum but no mass. I objected to a solution involving direct energy mass conversion in the atom. The link indicates a possible solution with mass being somehow attached to the photon. I do not have the physics to talk to it off the top of my head.
I think the problem is that you are trying to resolve it as a Newtonian process. Newton was damn good and came damned close but, after 300 years, science moved on and found a few cracks in his physics. But, even at that, Newton was close enough that, for every-day human-scale, his physics is still reliable enough to send rovers to Mars and land them safely.

A few things Newton had problems with are;
... He had no idea what gravity was even though the understood its effect well enough to give us his universal law of gravitation.
... He knew nothing of atoms, electrons, protons, binding energy, energy levels of electrons in atoms, etc.
... He assumed space was a Euclidean backdrop unaffected by matter or events.
... He assumed that time was a universal, completely independent of space and events.
... He assumed that mass and energy were completely separate and independent phenomena.

It is the last one that you are having problems with. Physics now knows and understands that there is an equivalence between mass and energy or that mass is just another form of energy. So much so that mass is expressed as an energy level in particle physics.

I don't recall reading that Newton ever tried to model where the energy released by fire came from. If he did then it must have been like his attempt to understand what gravity was... he just left it as god's mystery.

This seems to be where you are, not seeing where the energy released by fire comes from since mass is immutable and there was no source of energy. However, physics has understood since the very early 1900s that mass is not immutable but can be released as energy. Balancing mass or balancing energy is no longer sufficient... now we must balance mass/energy (which makes the answer to the question of the energy of fire obvious).

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