You obviously understand how microwaves work Corona. Perhaps you could answer a question that has been bothering me.
If it takes 10 minutes to cook a potato to the way I like, how long would it take to cook two identical potatoes?
I can tell from observation that the answer is not 20 mins because (unless my oven is different from everybody else’s) they will be over cooked. Is there a specific correlation between cooking time and mass?
I can equally level the same on you. Microwaves often focus a beam creating a hot spot hence you can get a steaming hot food thats frozen elsewhere. There is a correlation between water content and cooking time rather than mass. It was a friend working for Moulinex that told me its the on cycle time thats varied and not output of microwaves.
I do understand your point about the power being applied for different times for different settings.
I was vaguely aware that there were hotspots and that is why they have turntables.
I did not realise that it was the water content that determines the cooking time.
I did ask the question for a genuine reason. To cook rice for two people, I use half a cup of rice and 1.5 cups of water and get perfect rice after 8 minutes at 1000W. If I double the amounts to 1 cup of rice to 3 cups of water, after 8 minutes the rice is swimming in water. After 16 minutes it is dried out and stuck together. I was hoping there was a good guide to timing rather than just trial and error. I am guessing your answer would be “no” because estimating water content is difficult.
Microwave radiation agitates water molecules, causing heating.
I sort of understand that but what about the molecules of everything else? Do they not vibrate and heat?
Using my example of rice grains plus water. I have simply doubled everything so why does it not take twice the time to cook at the same power setting? The water content is simply doubled.
Is it because of this hotspot idea? Why does the turntable not even out the hotspots? I will get the answer I need by trial and error but it is always nice to understand why. It is certainly a more interesting subject than I first imagined.
Other molecules will vibrate, but to a much lesser extent. I don’t know about microwave hotspots, but I’d have a bet that commercial (expensive) units have a far better distribution than domestic (cheap) units.
Cooking time are not doubled because cooking is a function of elapsed time and temperature together. If cooking starts at an arbitrary 70 degrees and takes 5min, but you heat to that temperature after 2 mins, doubling the mass means that it will hit 70 after 4min and start cooking. If your standard meal is ready in 5min, doubling the load will mean it needs just 7min to cook.
That seems to make sense. Thanks. I’ll avoid recommending recipes using a microwave.
Just to say, my figures are purely as examples, not anything specific.
Yes, understood but it makes sense to me 
Most foods that we are likely to microwave contain a fair proportion of water, so I think it’s usually the water content that picks up the microwaves, starts bouncing around and then heats the rest of the food by conduction. Hence veggies cook quickest because they have a high water content.
Understood but it is relatively easy to write your idea as a mathematical equation.
The Ancient Mariner Theory of Relativity of Microwave Timings
For any given consistent power setting.
T = cM +K
Where :-
T = total cooking time in minutes
c = rate required to reach cooking temperature in minutes per gram
M = total mass of ingredients in grams (which is directly proportional to water content)
K = actual ingredient cooking time once temperature has been achieved and is independent of mass.
So how is this relevant in actual practice?
Taking my earlier example, I know that ½ cup of rice plus 1.5 cups of water (100gm + 3 X 75gm = 325gm) cooked for 8 minutes at 1000W gives two portions of perfectly cooked rice (separate grains and no residual water).
Now, if two extra people turn up for dinner, I can’t simply double the cooking time because the rice dries out and sticks. I have discovered by experiment that it requires 14 minutes.
So solving the simultaneous equations:-
8 = c X 375 + K … and
14 = c X 750 + K we get
c = 0.016
K = 2
(I am actually SO lazy asked AI to solve them for me and it worked !!!)
In other words if I need to cook rice for 6 people:-
T = 0.016 X 3 X 375 + 2 = 20
I explained all this to my rather bored sounding wife [feeling pretty smug emoji]
“yes but you have to stir the pot halfway through cooking to get the best results.”
What? How does that work? Is this connected to those unknowable unmeasurable hot spots? Back to the drawing board. [depressed emoji]
Ever tried cooking your rice in pan of water on a stove?
Now where is the fun in that?