Yes, I understand how all that functions. Humans get cooked down from perspiration, which is because the energy to evaporate sweat is partially comes form the heat on our body, and air flow helps with that.

But airflow itself doesn't equal cooking in the general sense, because it only works if you are removing heat by taking it to something that is at a lower temperature, can't violate newton's law of cooling.

You did provide a great explanation, even though I was already aware of all that.

This is the answer.

I have used thermal cameras in my line of work work a part in an oven.

And I have literally been able to see the reflection of my own body when I pointed the thermal camera at the metal walls. That's likely the issue here. An emissivity issue.

The coworker's explanation sounds like a misunderstanding of how convection works. Just because air is flowing, doesn't mean it's cooling down the metal. Flow doesn't equal cooler. You need to remove the thermal energy somehow. If it's a closed system the heat isn't going anywhere.

It has to do with the way that waves propagate through any medium.

The electromagnetic waves that travel down a conductor represent changes in the electromagnetic field across the charged particles. This does move the charge carriers. But it is the EM waves that are essentially transferring the energy.

For example, the rare at which the electricity travels down a copper wire is just about the speed of light. But the electrons themselves don't move that fast down the wire. They are accelerated back and forth and do drift down the conductor but the particles arent moving down the conductor at the speed of light. They move at what is called the drift velocity. Which is lower than it would take for you to walk. But that's because the energy is transferred via electromagnetic waves. It's not like a faucet or water where electrons flow like water.

And how you define how it flows in one direction depends on the scale. It does go back and forth but you can't violate the first law of thermodynamics. Power is energy over time. (Watts = Joules per second).

You can't have a passive load (the thing there needs electricity) sending energy back towards the generator (the thing that is making electricity) without violating the first law of thermodynamics. The one but caveat there is of course that the energy can be reflected back when it hits the load. That happens when the impedances don't match, which affects the power factor (which for the mathematically inclined is cosine of the phase angle between voltage and current.)

Yeah that's not what I'm talking about at all.

Yes I said it makes sense to consider that DC power. I never said otherwise there.

You seem to have misread my comment. What I said was that as a matter of convention, anything that isnt DC we called AC.

The phrase flowing back and forth can mean a number of things. My point was that it doesn't need to be negative to be considered AC.

When I work on power electronics, and still do, we often refer to the ripple at the output of the supply as an AC ripple as part of the DC. But yes of course we would never consider that an AC power supply. Of course we would still call that DC power. Sure.

Just to be clear. I said anything that isn't DC we refer to as AC. And you picked one very specific example to say "no everyone I talked to calls a DC power supply DC even if it has a ripple" which yeah or course they do. But that's not really related the point I was making

Yes. I think in their example tho they are thinking about power supplies that rectify and the smooth ac into a useful DC signal. And on practical terms many people consider the ripple negligible and call it a DC power supply.

But I think they are coming from a pretty simplified explanation and then the added nuances don't exactly work with the simplified explanation

Then you learned it wrong. (Or just a simplified explanation) I have a bachelor's in EE, the standard convention for the terms is that any signal that is not DC is considered AC.

You can for example take any AC voltage and add a DC offset which then makes it so that the entire wave is positive through an entire period.

Nothing has changed about the signal, other than you have shifted the wave enough to no longer be negative, this is most certainly NOT a DC signal.

But it is entirely positive.

Take amplifiers for example as well, the transiistors in the output stage of a class A amplifier are biased in a way that the entire signal is positive. This obviously is not a DC signal.

The issue with thinking of AC signals as requiring to be both positive and negative is that all the meaningful conventions fall apart when you consider signals that are not centered around zero .

An ac signal with a DC offset will pass through capacitors, and then lose the DC component. The same way an AC signal, with a DC offset will not see an inductor as short.

What you refer to as having a little bit of ripple tells me you're thinking strictly in terms of power.

So yes when people rectify a signal and then try to smooth it to convert from AC to DC you can accept a small ripple in the signal. yes I definitely see how someone would call that a DC signal because that is what you are looking for in that case. And the ripple is small enough to not cause an issue. But of course depends on how precise your power needs to be.

So alternating having charge flows back and forth is not entirely wrong. But it's just overly simplified and in EE we consider any signal that it's not DC to be AC. Because that is a more useful convention in terms of how the laws of physics govern electro-magnetics. Because you can have alternating current signals that are entirely positive (or negative)

This is true. But it is still said to be alternating. Alternating current includes anything that is not DC. Even it is positive during the entire cycle it's still AC.

The confusion comes from the fact that people don't understand what alternating current means.

It doesn't mean energy flows back and forth. It means the voltage and the current are alternating. The voltage is a potential difference. The current is charge per second.

The power is traveling down the conductor in a waveform. Like a wave. So even though the charge carrying particles are moving back and forth, it is still delivering energy to the electrons on the other side of the circuit.

Like a light bulb. You send energy to the bulb in sinusoidal waves. The waves delivers energy to the device that is used to create light.

You don't deliver the particles themselves. It is the particles that move from one voltage potential to another that deliver energy to a load across that voltage potential.

An electron has a fixed charge. The energy itself comes from the votlage potential. Volts =Joules/Coulomb. Or in other words energy/charge.

The electrons can deliver the energy be moving from a high potential to a low potential. Thats why we refer to voltages as a potential. Cause it is like moving from a state of high potential energy to a low one.

So even though the charge moves back and forth it is still delivering energy in one direction (assuming a matched impedance)

Nice.

Which is all you need since you can scale it from there of course.

This is really cool actually. And I don't care how much of a nerd I sound like saying an old calculator is cool.

Is that Rnd button a random number generator?