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tylerni7 t1_jba5rgd wrote

The distance will affect the field strength, which will fall off as the distance cubed.

However, this is NOT the same as efficiency: if the stove ran with no pan coupled to it, the power usage would be low (only resistive losses and some negligible energy from the field permeating the air).

So while things will get slower further away, the stove will also use less energy. Trying to estimate the actual effect is tough and depends a lot on practical things (like the specifications of the coil and its drivers and the magnetic permeability of the stovetop and surroundings), but it's probably fair to round it to zero in practice.


BitsAndBobs304 OP t1_jba6esg wrote

okay so placing a kitchen rag will affect energy cost less than 1%?


black_brook t1_jba9f02 wrote

It will actually heat the pan more using less electricity once it bursts into flames.


BitsAndBobs304 OP t1_jba9vuo wrote

lol why would it burst into flames


seckarr t1_jbaam37 wrote

Pan heats up. Heats up so much that it sets the rag underneath it on fire.


BitsAndBobs304 OP t1_jbabxvh wrote

why would the bottom of a pan get to 210C when cooking by induction? can you imagine cooking some piece of chicken at 210C in a pan?


kore_nametooshort t1_jbackit wrote

Frying pans run much hotter than that. Much hotter than ovens for sure.


upvoatsforall t1_jbafn1d wrote

They can get much hotter but if you don’t want to burn stuff you can cook at lower temperature. Some fancy new induction tops allow you to set the temperature of the pan. Non stick coatings burn off at around 500 F. So I keep a laser thermometer to keep tabs on the temp.


NeverPlayF6 t1_jbaqw17 wrote

Just a heads up- laser thermometers are actually infrared thermometers that measure the IR emitted as blackbody radiation. Each substance has a emissivity coefficient that has a significant effect on the measured temperature. Most IR thermometers are set to a default of 0.95 which is fantastic, since that is the emissivity value of cooking oil... but if you're trying to measure the surface temperature of a pan, it could vary substantially.


tjeulink t1_jbacrz5 wrote

thats a pretty normal temperature to cook chicken at. searing meat is done 315c. cooking chicken and other meats usually at 150-200c. usually when cooking meat you sear it first to lock in moisture and flavor.


DriizzyDrakeRogers t1_jbajlac wrote

I sear steaks, pork chops, and chicken at 400-420F (around 210C) on my induction cooktop all the time.


Calembreloque t1_jbantwr wrote

Do you think that induction cooks things without heating them up somehow? There's no direct flame but at the end of the day the principle is still to heat the bottom of the pan so you can cook its contents. A quick look online will tell you that induction ovens can heat things up to 350°C.


black_brook t1_jbanm1e wrote

People often underestimate the temperature the frying pan gets to because the food is actively cooling off by the moisture in it changing phase to steam. The pan needs to be hotter than the food will actually cook at to compensate for this, and the bottom of the pan will be hotter than the surface of the pan which is in contract with food and having heat actively draw off.


atomfullerene t1_jbaq4wy wrote

The pan has to be hotter than the chicken to heat it effectively


[deleted] t1_jbaaorh wrote



BitsAndBobs304 OP t1_jbabqvj wrote

you think the bottom of a pan will get to 210C when cooking by induction? can you imagine what would happen to the oil IN the pan at 210c?


littledeadfairy t1_jbacc2z wrote

210 degrees C is considered medium heat lol. Have fun with your little kitchen fire.


Calembreloque t1_jbangf7 wrote

Virgin olive oil (which has one of the lowest smoke points) starts smoking around 190°C, so if you use other oils (avocado, sunflower), strictly nothing would happen at 210°C. 210°C is a perfectly standard temperature for cooking. If you want your chicken to cook to 75°C (the safe temperature), your pan has to be much hotter than that otherwise it will take hours for your chicken to heat up.


ErikTheAngry t1_jbafbx8 wrote

A thin silicone mat will work fine for what you want, and handle most of the temperatures you're going to be exposing it to (the pan is going to be hot, even if there is no radiant heat from the element itself).

They'll still melt if you go too hot, but for your average cooking, they're enough.

It's good for cast iron cookware. Shelters the ceramic top from the iron.


dastardly740 t1_jbaj2ja wrote

The exception is probably when cast iron is used for searing. If all goes well, that should significantly exceed the temperature kitchen silicone mats can handle.


takesalicking t1_jban3wk wrote

Why not aluminum foil? It's non-magnetic, thin, won't "burst into flames" or melt.


ErikTheAngry t1_jbaoe0o wrote

It'll probably stop the mess, assuming it doesn't tear.

Though personally I'd be worried about fumes.. confined between the pan and the element the temps could be considerably higher than the surface of the pan itself (not unlike how the temps rise when you put a lid on a pot). Aluminum fumes are no joke, which start to be a concern around 600C. Of course at those temps, silicone would just be a bubbling mess too.

Foil won't do anything to protect the ceramic top from a heavy piece of iron though. The silicone mat will provide a bit of padding to help avoid scraping the ceramic, and it offers a little leeway in setting down the cast iron.

All while being reusable.


BitsAndBobs304 OP t1_jbajj8t wrote

i've seen some mats made for induction cooking on amazon. however, some reviews talking about them melting (which results not just in money loss of item, but very hard or impossible to remove stain on the expensive stovetop).

now, some reviews are likely to be from ill informed people with an electric stove. however, some claim to be certain that they have induction stove and they still melted, which worries me.


brainwater314 t1_jbac7pj wrote

The slower heating allows heat to leak out while you're not using the pan because it's not hot enough yet, and I'd bet a rag is at least a couple mm thick and would reduce the heating speed noticeably, so I'd say it would reduce the efficiency overall by at least 5% if not 10% or 20%. One of those thin lint free towels would be a better choice.


BitsAndBobs304 OP t1_jbadxk2 wrote

you mean microfiber? that has a melting point much lower than cotton


brainwater314 t1_jbaepyn wrote

No, I thought the really thin dish towels were called "lint free". They weren't made of plastic and weren't microfiber cloth. They were more like the thickness of a t-shirt than a towel. They just didn't have the fluff that makes towels so thick.


msalerno1965 t1_jba416f wrote

Like putting a case on your phone, and wirelessly charging it. It does affect it. How much? Inverse square law most likely applies.

Which basically means, double the distance from a radio (magnetic) source, quadruple the signal loss.

Also why people crying about cell phone tower emissions while holding their phone to their ear are ... delusional.

Caveat: I have no degrees in anything, just a 40 year career in IT.


NullHypothesisProven t1_jbaew5c wrote

Simple experimental solution for you: fill a pot with a known volume of tap water. Put it on the burner and time how long it takes to boil. Dump that water out. Dry the pot, cool it to room temperature. Fill with the same volume of tap water. Put the rag down, put the pot on top, turn on the burner to the same setting, time how long it takes to boil. Compare.


Sherlock-Holmie t1_jba7npq wrote

We would need a diagram of the specific induction cooker to calculate this because you have to know the distance from the coils to the pan

Generally though, the dirt at the bottom shouldn’t matter. They’re generally at the micron level of thickness


BitsAndBobs304 OP t1_jba8j1f wrote

hwo about the kitchen towel?


MrMuf t1_jbaekvx wrote

Kitchen towel is not a good example since it comes in many shapes and sizes. Also it compresses down depending on the weight on top of it. Also the risk of fire. If you want to cover the pan, use silicone or something


Sherlock-Holmie t1_jba9ut5 wrote

From one pic I’ve seen, it seems that the cover is pretty much on top of the coils.

The mutual inductance change ratio it does will be (r_initial/r_final)^2 If the towel is the same thickness as the cover, this’ll be r_final=2*r_initial (1/2)^2=1/4 whichll mean 1/4 the power

If the cloth is half the thickness of the cover, then r_final=1.5*r_initial (1/1.5)^2=.44

If the cloth is 1/8th the thickness, it’ll be 80% the same efficiency


upvoatsforall t1_jbafwsr wrote

I’ve seen silicone mats for this purpose to prevent scratching of the cooktop. Never tested them myself though


BitsAndBobs304 OP t1_jbajmq7 wrote

i've seen some mats made for induction cooking on amazon. however, some reviews talking about them melting (which results not just in money loss of item, but very hard or impossible to remove stain on the expensive stovetop).

now, some reviews are likely to be from ill informed people with an electric stove. however, some claim to be certain that they have induction stove and they still melted, which worries me.


FantasticFunKarma t1_jb9xihb wrote

It might a tiny bit. The magnetic field created by the coil in the stove top will decrease in strength the further away from the coil. So putting for example a tea towel to catch water from the pasta pot under the pot might slightly affect that distance. In practical terms it is not noticeable.


BitsAndBobs304 OP t1_jb9zei5 wrote

Do you have an idea of how big the effect is then? Below 0,1% efficiency decrease for a thin cotton kitchen rag?


[deleted] t1_jb9zzgb wrote



BitsAndBobs304 OP t1_jba02ah wrote

Haha okay ;)


FBogg t1_jba5l1e wrote

it wouldn't be a loss of efficiency; the energy transfer will always be 100% efficient. It will however reduce the power consumption, as someone else said with a relation ship of inverse square. the material thickness will affect energy transfer by a large amount


BitsAndBobs304 OP t1_jba5seb wrote

>t will however reduce the power consumption



FBogg t1_jbapyjf wrote

further distance between magnetic elements = weaker magnetic force = lower transmission at constant line voltage.


GhostBurger12 t1_jba0qvp wrote

Use pieces of wood of different thicknesses, a set volume of water, and a small pot.

Test & time how long it takes the water to reach a rolling boil.


BitsAndBobs304 OP t1_jba1baq wrote

a difference of 1-3% could be significant in expenses over a year but would be hard to detect reliably in home experiments without going for countless tests


GhostBurger12 t1_jba1xzl wrote

1-3% still isn't much, because that's only the net power used by the induction plate, vs your total daily power usage.

If you have a desktop computer & graphics card, that's probably eating more of your power.


BitsAndBobs304 OP t1_jba62z8 wrote

computers lower their consumption when they're not being used to full computational requirements