[alancalverd]

You found a method where the temperature difference between ingoing and outbound  was essentially constant.

Actually not the case. We delivered electrical energy or ionising radiation into a multi-layer graphite/vacuum calorimeter and measured the time it took for the sensing thermistor in the middle to change by 1 milliohm. The clever bit was designing a bridge that reproducibly offset by 0.001 ohm to +/- 0.1%. 

[hamdani yusuf (OP)]

And, if it's not at equilibrium, it doesn't have a properly defined temperature.

If that's the case, the curve below won't be possible because the temperature is measured while heat is being transferred to/from the system.

[Bored chemist]

According to Kirchhoff's law of thermal radiation, a good absorber is also a good emitter for the same radiation frequency.

There's a good chance that I told you about Kirchhoff's radiation law. I have cited it quite a bit in these pages.

[Bored chemist]

And, if it's not at equilibrium, it doesn't have a properly defined temperature.

If that's the case, the curve below won't be possible because the temperature is measured while heat is being transferred to/from the system.

If you look carefully, you will se the only bits of the line where the temperature is constant are the bits where there are two phases in equilibrium.

It will melt before reaching equilibrium.

I know.

And it would melt

Why do you keep posting stuff that we clearly already know?

[hamdani yusuf (OP)]

But, in principle, your spinning magnet warms it up a bit.

The effects are much less than Eddy current generated in metals, thus doesn't significantly change the temperature measurement.

The experiment in the video clearly shows this.

Eddy Current Demo #electromagnetic induction #physics #physicsninja

[hamdani yusuf (OP)]

If you look carefully, you will se the only bits of the line where the temperature is constant are the bits where there are two phases in equilibrium.

It's not an equilibrium when the energy transfer into the system is larger than the energy transfer out from the system. By your reasoning, liquid water in the graph is not well defined. You won't be able to tell when the water temperature reach 300 K, for example.

[hamdani yusuf (OP)]

Why do you keep posting stuff that we clearly already know?

Because you keep saying that temperature is not well defined before equilibrium is reached. But we know that glass melts at its melting temperature.

[paul cotter]

Glass does not have an mp as such, it progressively softens as the temperature rises. Glass behaves as a supercooled liquid rather than a solid.

[alancalverd]

It's not an equilibrium when the energy transfer into the system is larger than the energy transfer out from the system.

Except for the case of "dynamic equilibrium". A small volume of material can be heated almost uniformly by ionising radiation or microwaves, and even in the common (and remarkably complicated) case of an egg in boiling water we can define the temperature any depth and any point in time, which is why we use  roasting thermometers and variable-temperature ovens to determine the final state of food.

[hamdani yusuf (OP)]

It's not an equilibrium when the energy transfer into the system is larger than the energy transfer out from the system.

Except for the case of "dynamic equilibrium". A small volume of material can be heated almost uniformly by ionising radiation or microwaves, and even in the common (and remarkably complicated) case of an egg in boiling water we can define the temperature any depth and any point in time, which is why we use  roasting thermometers and variable-temperature ovens to determine the final state of food.

The temperature of a system is determined by how we define its boundaries.

[hamdani yusuf (OP)]

Glass does not have an mp as such, it progressively softens as the temperature rises. Glass behaves as a supercooled liquid rather than a solid.

We can use the point where the bulb starts to lose its structural integrity.

[hamdani yusuf (OP)]

Here's another thought experiment to check our understanding of temperature, and its relationship with entropy.
Two isolated containers each with 1 cubic meter volume. Their internal surface is perfectly elastic, thus doesn't absorb energy from molecules hitting it. A small pipe equipped with a closed valve is connecting those containers. Initially, the first container contains ideal gas at STP, while the second container is at vacuum. The whole system is inside a space lab, isolated from outside  world.
When the valve is opened, some gas molecules will move to the second container. Since the collision with the container walls are elastic, they maintain their kinetic energy. At equilibrium, the flow rate from the first container equals the reverse flow. The pressure of both containers become half of standard pressure. The temperature is still at standard temperature, according to ideal gas law, P.V=n.R.T
The gas, which initially occupied 1 cubic meter of volume, now occupy 2 cubic meter.

[Bored chemist]

But we know that glass melts at its melting temperature.

We know that the melting point of something (when it has one- glass doesn't) is defined as the temperature where the liquid and solid phases are in equilibrium.

[Bored chemist]

But, in principle, your spinning magnet warms it up a bit.

The effects are much less than Eddy current generated in metals, thus doesn't significantly change the temperature measurement.

The experiment in the video clearly shows this.

Eddy Current Demo #electromagnetic induction #physics #physicsninja

That's a lot of trouble to go to in order to show that you don't know what the phrase "in principle" means.

[Bored chemist]

Here's another thought experiment to check our understanding of temperature, and its relationship with entropy.
Two isolated containers each with 1 cubic meter volume. Their internal surface is perfectly elastic, thus doesn't absorb energy from molecules hitting it. A small pipe equipped with a closed valve is connecting those containers. Initially, the first container contains helium gas at STP, while the second container is at vacuum. The whole system is inside a space lab, isolated from outside  world.
When the valve is opened, some gas molecules will move to the second container. Since the collision with the container walls are elastic, they maintain their kinetic energy. At equilibrium, the flow rate from the first container equals the reverse flow. The pressure of both containers become half of standard pressure. The temperature is still at standard temperature, according to ideal gas law, P.V=n.R.T
The gas, which initially occupied 1 cubic meter of volume, now occupy 2 cubic meter.

Why do you keep posting stuff that we clearly already know?

By the way, if you say "an ideal gas" rather than "helium", you can get round the problem that it isn't actually ideal.

[hamdani yusuf (OP)]

By the way, if you say "an ideal gas" rather than "helium", you can get round the problem that it isn't actually ideal.

I've changed helium with ideal gas to avoid unnecessary arguments.

In this scenario, we get an increase in system entropy without any change in temperature nor internal energy.

[hamdani yusuf (OP)]

But, in principle, your spinning magnet warms it up a bit.

The effects are much less than Eddy current generated in metals, thus doesn't significantly change the temperature measurement.

The experiment in the video clearly shows this.

Eddy Current Demo #electromagnetic induction #physics #physicsninja

That's a lot of trouble to go to in order to show that you don't know what the phrase "in principle" means.

I think it's necessary, since you didn't seem to realize how insignificant it was.

[Bored chemist]

I think it's necessary, since you didn't seem to realize how insignificant it was.

As I said,

you don't know what the phrase "in principle" means.

[Bored chemist]

In this scenario, we get an increase in system entropy without any change in temperature nor internal energy.

Lucky us!
You can calculate it if you like.
https://en.wikipedia.org/wiki/Sackur%E2%80%93Tetrode_equation

[hamdani yusuf (OP)]

These videos show that energy transfer by radiation can be passed through material as well as being absorbed. Other experiments show that it ca also be reflected. This is like impedance matching problem in electronic engineering.