oh, my shitty hot plate is one of those coils. it’s really shitty.
its problem is that it only has two settings, on and off, and it reaches the desired temperature by cycling between those. and full blast hot boils the water too fast.
Aluminum is more conductive than steel so eddy currents flow more easily in aluminum. Some pans have an aluminum disc inside, for induction stovetops. Maybe it’s too much aluminum vs just a disc? His hot plate might be too low power or not induction just a glass top
This is wrong. Induction requires magnetism, not conductivity. A pure aluminum pan will not get hot on an induction hob. Some aluminum pans have an iron or steel plate inserted in their base to allow them to work on induction.
No, I am saying the pan has to be magnetic, which is what I have said 3 times now. You are completely wrong about how induction cooking works.
Heat from eddy currents is a small fraction of what magnetic hysteresis can produce. You can technically heat any good conductor with eddy currents alone if it is non-magnetic, but the equipment needed is significantly more complex and power hungry than induction cooking hobs.
Here are the results of a quick internet search explaining it from various sources.
Also, if you just look at the FAQ or owners manuals for any induction cooktop out there, they will all tell you the pans have to be magnetic to function. Not “for best performance”, to function at all.
It really sounds like you are thinking exclusively of induction forges, which can heat non-magnetic materials. Induction cooking hobs absolutely cannot heat non-magnetic materials to any noticeable or useful degree, they do not have the frequency range or the power for eddy currents alone to be sufficient. Induction forges on the other hand HAVE TO have the power to heat with just eddy currents because if you heat iron or steel up to glowing, it loses magnetism (and the heating slows significantly past that point).
Ferrous metals (like iron, nickel, and cobalt) have an additional, more powerful source of heat.
These materials are composed of small magnetic regions called domains. The alternating magnetic field from the induction coil causes these domains to rapidly flip their polarity, billions of times per second.
This rapid flipping creates immense internal friction, which generates significant heat. This hysteresis effect is what makes ferrous metals heat so much more quickly and efficiently than their non-ferrous counterparts.
In ferromagnetic materials like iron and steel, a second heating mechanism kicks in.
As the alternating magnetic field repeatedly reverses the magnetic domains within the material, the friction generates additional heat known as hysteresis losses.
This effect disappears once the material crosses its Curie temperature (around 770°C for steel), at which point ferromagnetic properties are lost. Above that point, eddy currents carry the full heating load.
For industrial heat treatment of carbon steel, both effects work together in the lower temperature ranges, delivering faster heating rates.
Because we’re working with AC, we need a small skin effect, which is given by the inverse square root of [pifrequencypermeability*conductivity]. It’s permeability that’s going to be the deciding factor here, because all metals have reasonably similar conductivity but ferromagnetic materials have four orders of magnitude higher permeability.
This also means that steel which is not ferromagnetic will not work on an induction stovetop. The stove will detect it and the chip will reject the pan to prevent damage to the coils.
like a hot plate?
which one my hot plate is too shitty to use my moka pot on but i have zero problems using the moka pot over gas
Probably because your moka pot is aluminum (or otherwise non-magnetic) so induction can’t heat it.
oh, my shitty hot plate is one of those coils. it’s really shitty.
its problem is that it only has two settings, on and off, and it reaches the desired temperature by cycling between those. and full blast hot boils the water too fast.
Oh yea, that’s a different problem. One of the big drawbacks of all radiant electric unfortunately.
Aluminum is more conductive than steel so eddy currents flow more easily in aluminum. Some pans have an aluminum disc inside, for induction stovetops. Maybe it’s too much aluminum vs just a disc? His hot plate might be too low power or not induction just a glass top
This is wrong. Induction requires magnetism, not conductivity. A pure aluminum pan will not get hot on an induction hob. Some aluminum pans have an iron or steel plate inserted in their base to allow them to work on induction.
OK you’re saying the higher resistance of the steel is needed for adequate heat. Got it
No, I am saying the pan has to be magnetic, which is what I have said 3 times now. You are completely wrong about how induction cooking works.
Heat from eddy currents is a small fraction of what magnetic hysteresis can produce. You can technically heat any good conductor with eddy currents alone if it is non-magnetic, but the equipment needed is significantly more complex and power hungry than induction cooking hobs.
You’re wrong too, what on Earth does hysteresis have to do with heating??
Here are the results of a quick internet search explaining it from various sources.
Also, if you just look at the FAQ or owners manuals for any induction cooktop out there, they will all tell you the pans have to be magnetic to function. Not “for best performance”, to function at all.
It really sounds like you are thinking exclusively of induction forges, which can heat non-magnetic materials. Induction cooking hobs absolutely cannot heat non-magnetic materials to any noticeable or useful degree, they do not have the frequency range or the power for eddy currents alone to be sufficient. Induction forges on the other hand HAVE TO have the power to heat with just eddy currents because if you heat iron or steel up to glowing, it loses magnetism (and the heating slows significantly past that point).
https://kindle-tech.com/faqs/what-materials-can-be-induction-heated
https://axiomht.com/blog/how-does-induction-heating-work/
https://en.wikipedia.org/wiki/Induction_heating
TIL thanks
Because we’re working with AC, we need a small skin effect, which is given by the inverse square root of [pifrequencypermeability*conductivity]. It’s permeability that’s going to be the deciding factor here, because all metals have reasonably similar conductivity but ferromagnetic materials have four orders of magnitude higher permeability.
This also means that steel which is not ferromagnetic will not work on an induction stovetop. The stove will detect it and the chip will reject the pan to prevent damage to the coils.