How long does it take a microwave oven to warm up?

How long does it take a microwave oven to warm up?

I often cook things that take maybe 7 or 8 seconds. Maybe if they're really small they take 5 but it's hard to know in advance and I really dislike most overcooked things. Undercooked, one can just cook it some more but is two 5-second zappings the same as one 10-second zap?

Or does it take a second (or 2 or 3 or more) to get the waves churning, so two 5-seconds is more like 9 seconds (or 8 or 6)?

I need to know so that eventually I'll know the proper time for a particular food, without stopping and checking**.

Has anyone read about this? Or other oscillators?

**This actually raises another question. I'm pretty darn good at predicting how much time I need to microwave something, and once in a while I can even remember from experience. (Cocoa from refrigerated milk is 2 minutes. An eggroll of a given size is 2 minutes 40 seconds, even though wrapper says 4 minutes.)

But what if part of something much bigger than 10-second food is cooked enough and I take it to the table and start eating and when I get to another part, find that it is not cooked enough. By this time all of it has cooled some. In that case, it's not the microwave warm-up time that would matter, but am I right that there is still food warm-up time? If the food is 70^, it might not even start cooking until the part that cooks reaches, what, let's assume 110. (Or maybe someone has a real number for a given food)

So if one is eating for 15 minutes, the 120 degree food will have cooled off to 80 degrees, and if I put it back in, it still has to get back up to 110 again, before it even starts cooking again, is that right? That could take 20 or 30 seconds or more, depending on how much food there is and other details. I dont' mind the extra time, but I would like it if someone could provide real-life numbers so I could better estimate how long the 2nd part of the cooking will take.

Reply to
micky
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Unless I've missed something, microwave ovens don't heat up.

Reply to
ItsJoanNotJoann

micky explained on 11/30/2016 :

The energy transfer is nearly immediate. The oven only warms up because of the food warming up.

Some items which I microwave would end up having cold or cool spots, so I used to cook say a three minute item by cooking for two minutes and then allowing the heat to spread for a couple of minutes, and then zap for another minute or so.

I now have a new microwave oven with a turntable (the other had a reflector) to help avoid the spottiness. The ovens power output is also an important factor to consider.

Reply to
FromTheRafters

The m-oven dont heat up! The food heats from the inside and m-waves cause the water molecules to heat. Food has to have moisture in it in order to heat up. If you put something in there that has no moisture, it wont get warm or hot. Thats why a plastic bowl wont heat up, only the food inside of it gets warm.

Reply to
Paintedcow

The heater in the magnetron tube takes a couple seconds to warm to the point where it will emit electrons. You can hear it easily on the old transformer microwaves, the fan starts and it begins to hum, then a couple seconds later the hum gets much louder. That louder hum is when the magnetron tube starts conducting.

Newer microwaves with switching power supplies may delay turning on the HV until the heater has warmed up, and they may not have that transformer hum, so it may be harder to tell when the RF comes on.

Jon

Reply to
Jon Elson

Have you ever used a microwave oven?

I still hear this myth being pushed. Food does NOT heat from the inside, it heats from the outside in. DUH!!

nb

Reply to
notbob

I find it easier to microwave for longer periods of time at a lower setting to get even heat.

Reply to
Frank

Yes, about 1/4" penetration. Fat molecules heat fastest followed by sugar. Dry stuff is hardest to heat. Once you understand how it works you get better results.

Standing time is important too. The molecules are still active a while after the mw is off and it allows the heat to penetrate more and hot spots to dissipate.

The myth of heating from the inside is easy to understand. Just like the pies at McDonalds warns of the inside being hot, the sugary inside will heat faster than the dry outside though they both received the mw energy at the same time.

Reply to
Ed Pawlowski

Yes, the new MW oven has programmable settings for power level and rest periods and such for better results. The old one only had a single knob with minute marks on it and a bell that softly, almost inaudibly, went 'click' when the time expired.

The old one is 26 years old, but it still works.

Reply to
FromTheRafters

Me, too and my microwave oven is a 1200 watt model. I've found out if I heat a mug of soup for 3½ minutes at 60% power vs. 2 minutes at 100% power I get no boil overs and even heating. It took a while for me to hit on this power and time limit when upgrading from an 800 watt model. I sure did get tired of cleaning up messes.

:-)

Reply to
ItsJoanNotJoann

Stick a compact fluorescent light bulb in the Uwave. It wil normally glow as soon as the microwaves actually come into the oven from the magnetron. It should be less than 2 seconds from the time you push the start button.

Reply to
hrhofmann

....is jes that. A myth.

Nuke a potato. No dry. No layers. No myths.

The outside cooks sooner than the inside.

All the rest is ignorance or lack of experience. ;)

nb

Reply to
notbob

+1, You are the only one who did not lambast the OP for using the term 'warm up' to mean 'cause the ambient MW intensity to reach its operational range'.

When I am judging time for extremely small loads (like softening butter without liquifying it), I allow 4 seconds for my oven.

I find that the hum does not get louder though. Instead, I notice that the fan speed lowers a bit, presumably because the supply voltage for the fan is then being loaded down by the power consumption by the magnetron.

Reply to
Mike Duffy

I had an Amana Model 2, that looked just like the drawings of microwaves that were used for decades. It lasted many years. I got it used around

1975 and met its earthly demise around 2000. . Although the insulation on the diodes had failed** and it sparked, so I covered the open parts with GE silicon sealant, and something else I fixed, and eventually the power transformer broke, I think it was. They wanted 300 dollars for it and my pointing out that they should take 80 since I coudl buy a new one for 80 didn't help. They lowered the price to the repairmans price of 200 roughly.

**Amanda didn't want to send me a schematic. I had to beg, and promise I knew what I was doing and wouldn't kill myself. She relented.

Reply to
micky

My Panasonic inverter seems to take up to 3 seconds to get going. That device has a variable supply, which it can control heat output. Most others are instant on.

Food still is cooking when power is off. As it cools it's also heating cooler areas. Usuall recommended to wait one minute before eating. Enclosed containers also equalize heating by steam. The microwave is a bit over 2 inches in length, so not all parts receive equal heating. There is usually the rotating plate, but some have rotating devices in waveguide to spread out the waves to also help equalize.

Greg

Reply to
gregz

+1 I was going to say the same thing. It depends on the microwave but my Panasonic is just like yours. So, 5 seconds is really 2 seconds and 10 seconds is really 7 seconds.

To the OP, two 5's is definitely not the same as one 10. As others said, you should be able to figure out the start-uip time for your particular oven.

Reply to
Pat

Micky,

Heating improves the physical "eatability" of products and also beats the crap out of bacteria. If you cook for under the prescribed time to suit your tastes then you need to understand about the bacteria.. Don't poison yourself. Sorry, can't help you with cooking times.

Dave M.

Reply to
David L. Martel

When I tested it long ago, it took 2 seconds for the radiation to start hitting.

So a 2 second heating did nothing, a 3 second heating was actually 1 second, but a 60 second heating was 58 seconds which is close enough.

My wife has a strategy. If it needs 10 seconds, she hits 11, which lets her hit the same button twice instead of moving over to the zero and maybe missing. Same for 22, 33, 44 seconds. They're all close enough.

The way I tested it was to put a piece of wire in and watch for it to spark. I used a twist tie, bent in a rabbit ear antenna shape, at approximately the half wavelength. don't try this at home.

Reply to
TimR

ItsJoanNotJoann wrote: " Me, too and my microwave oven is a 1200 watt model. I've found out if I heat a mug of soup for 3½ minutes at 60% power vs. 2 minutes at 100% power I get no boil overs and even heating. It took a while for me to hit "

You've learned something few realize about microwave ovens: 100%, or Full power, is good for only one thing: boiling water.

50-60% on a microwave corresponds to medium on a typical electric stove, and is where most cooking should go on. It will require longer cooking times, but will cook more evenly and without scorching.

As for someone else on here suggesting microwaves do not cook from the inside out: A year ago I had occasion to warm up a frozen stick of butter. So I programmed 4 minutes on level 3(medium low). What came out was a mostly intact stick with HOLES IN THE SIDES where hot butter had poured out from INSIDE.

Reply to
thekmanrocks

snipped-for-privacy@gmail.com brought next idea :

The electromagnetic waves will penetrate some materials better than others and in some cases will vibrate polar molecules (usually H2O) on the inside which then heat surrounding material.

Reply to
FromTheRafters

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