If you’re wondering whether an induction coil can heat two layers of metal, the answer is no. Let’s discuss why.
The Setup
Imagine we have an induction coil that is strong enough to heat a sheet of metal. We can place a sheet of ferromagnetic metal close to the coil, at a distance , and it gets heated to temperature . Or, we can place it farther away at a distance , and it gets heated to temperature .
Now, let’s say we have two identical sheets of metal at once, one at distance and one at distance . They are on the same side of the coil, with some insulator between them (the insulator does not conduct electricity, is not ferromagnetic, and does not conduct heat well). We want to know if the sheet farther away from the coil will heat up at all, or whether the closer sheet will shield it from the electromagnetic field in some way. We also want to know what temperature and the sheets in this experiment will be, and whether they will be higher, lower, or the same as and .
Furthermore, we need to consider what happens if there is a small conducting connection between the two sheets of metal. For example, a wire which touches both the close and the far one, but most of their surface is still separated.
The Answer
The answer is no, the sheet farther away from the coil will not heat up at all. The penetration depth of the magnetic field in the first sheet is too small.
The Math Behind It
The penetration depth is typically given by a formula looking something like this:
Where is the resistivity of the material (we will assume steel), is the magnetical permeability (again, we will assume steel), and is the frequency of the magnetic field (20 kHz is on the lower end of the range used in induction stoves). Higher frequencies would give even shorter penetration depths. For example, assuming each side of the waffle iron is considerably thicker than 0.043 mm, a plan to use two layers of metal won’t work.
Application to Waffle Irons
If you are planning to use a cast iron waffle iron on an induction stove, you need to consider the thickness of the material. It would be best to use only one layer of cast iron, as additional layers will not heat up to a sufficient temperature to cook the waffles evenly. Also, keep in mind that some heat will conduct through the waffle itself, and it is best to turn it regularly to ensure both plates get hot.
Conclusion
In conclusion, using multiple layers of metal on an induction stove is not a viable option. While the first sheet may heat up, subsequent layers will not adequately heat for proper cooking. When using a cast iron waffle iron, it is best to use only one layer and ensure regular turning for even cooking.
Can an Induction Coil Heat Two Layers of Metal?
If you’re wondering whether an induction coil can heat two layers of metal, the answer is no. Let’s discuss why.
The Setup
Imagine we have an induction coil that is strong enough to heat a sheet of metal. We can place a sheet of ferromagnetic metal close to the coil, at a distance
, and it gets heated to temperature 
. Or, we can place it farther away at a distance 
, and it gets heated to temperature 
.
Now, let’s say we have two identical sheets of metal at once, one at distance
and one at distance 
. They are on the same side of the coil, with some insulator between them (the insulator does not conduct electricity, is not ferromagnetic, and does not conduct heat well). We want to know if the sheet farther away from the coil will heat up at all, or whether the closer sheet will shield it from the electromagnetic field in some way. We also want to know what temperature 
and 
the sheets in this experiment will be, and whether they will be higher, lower, or the same as 
and 
.
Furthermore, we need to consider what happens if there is a small conducting connection between the two sheets of metal. For example, a wire which touches both the close and the far one, but most of their surface is still separated.
The Answer
The answer is no, the sheet farther away from the coil will not heat up at all. The penetration depth of the magnetic field in the first sheet is too small.
The Math Behind It
The penetration depth
is typically given by a formula looking something like this:
Where
is the resistivity of the material (we will assume steel), 
is the magnetical permeability (again, we will assume steel), and 
is the frequency of the magnetic field (20 kHz is on the lower end of the range used in induction stoves). Higher frequencies would give even shorter penetration depths. For example, assuming each side of the waffle iron is considerably thicker than 0.043 mm, a plan to use two layers of metal won’t work.
Application to Waffle Irons
If you are planning to use a cast iron waffle iron on an induction stove, you need to consider the thickness of the material. It would be best to use only one layer of cast iron, as additional layers will not heat up to a sufficient temperature to cook the waffles evenly. Also, keep in mind that some heat will conduct through the waffle itself, and it is best to turn it regularly to ensure both plates get hot.
Conclusion
In conclusion, using multiple layers of metal on an induction stove is not a viable option. While the first sheet may heat up, subsequent layers will not adequately heat for proper cooking. When using a cast iron waffle iron, it is best to use only one layer and ensure regular turning for even cooking.