In general stove heat moves from the bottom to top in even manner. But in case of micro oven most of the times top layer only we get more heat compare to bottom. What could be the possible reason.
Do you mean microwave oven?
the mode of heat transfer is the radiation.
Heat is generated when the energy contained in the microwave radiation excites atoms in the water molecules in the food, causing them to move faster (which is what is meant by “heat”). The microwaves can penetrate the food, so that the induction of heat takes place not just from the outside, as on a stove or in an oven, but also from the inside, as the water heats up. This is one reason cooking in a microwave oven is so fast.
More details
https://www.quora.com/How-is-heat-transferred-when-cooking-food-in-a-microwave
When microwave ovens became popular in the 1970s, they lifted household convenience to a new level. A conventional oven heats food very slowly from the outside in, but a microwave oven uses tiny, high-powered radio waves to cook food more evenly (loosely speaking, we sometimes say it cooks from the "inside out"—although that isn't quite correct). This is why a microwave can cook a joint of meat roughly six times faster than a conventional oven. Microwave ovens also save energy, because you can cook immediately without waiting for the oven to heat up to a high temperature first. Let's take a closer look at how they work!
A microwave is much like the electromagnetic waves that zap through the air from TV and radio transmitters. It's an invisible up-and-down pattern of electricity and magnetism that races through the air at the speed of light (300,000 km or 186,000 miles per second). While radio waves can be very long indeed (some measure tens of kilometers or miles between one wave crest and the next), they can also be tiny: microwaves are effectively the shortest radio waves—and the microwaves that cook food in your oven are just 12 cm (roughly 5 inches) long. (You can read more about electromagnetic waves in our article on the electromagnetic spectrum.)
Despite their small size, microwaves carry a huge amount of energy. One drawback of microwaves is that they can damage living cells and tissue. This is why microwaves can be harmful to people—and why microwave ovens are surrounded by strong metal boxes that do not allow the waves to escape. In normal operation, microwave ovens are perfectly safe. Even so, microwaves can be very dangerous, so never fool around with a microwave oven. Microwaves are also used in cellphones (mobile phones), where they carry your voice back and forth through the air, and radar.
How does a microwave turn electricity into heat? Like this!
Additional details here
https://www.explainthatstuff.com/microwaveovens.html
Microwave Radiation
Microwave radiation utilizes short, high-frequency waves that penetrate food, which agitates its water molecules to create friction and transfer heat. If you're heating a solid substance, this heat energy is transferred throughout the food through conduction, while liquids do so through convection.
Microwave heat transfer usually cooks food faster than infrared radiation, as it is able to penetrate foods several inches deep. Keep in mind that microwave radiation works best when cooking small batches of food.
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https://www.webstaurantstore.com/blog/postdetails.cfm?post=976
A detailed video on your topic here
https://www.youtube.com/watch?v=kp33ZprO0Ck
Microwave Ovens Safety: Do's & Don'ts
https://www.youtube.com/watch?v=svvrF4FMPEw
Microwave Ovens - How do they work?
https://www.youtube.com/watch?v=44mEhdd8KuM
Microwaves, the waves, are actually a form of energy that is used in Microwaves, the appliance, to heat your food. In terms of wavelength and frequency, microwaves fall between infrared radiation and radio waves. In case that form of reference means nothing to you, a microwave is about 12 centimeters from crest to crest or 10^-2 meters. This wavelength is easily absorbed by most foods, specifically water molecules, which cause the food to heat up.
https://www.youtube.com/watch?v=BoInZiGZPd0
A microwave heat transfer model for a rotating multi-component meal in a domestic oven: Development and validation
Article A microwave heat transfer model for a rotating multi-compone...
Article Principles of Microwave Combination Heating
Principles of Microwave Combination Heating
Faster, automated cooking of foods with improved quality can be realistically achieved only by a combination of heating modes such as microwave, infrared, and hot air, which, by themselves, have limitations. Combining heating modes poses many technical challenges. To meet these challenges, comprehensive understanding of microwave combination heating is needed. This article is the synthesis of the most fundamental‐based approaches (theoretical and experimental) in an attempt to provide the most succinctly said principles that can be useful to a product or process designer in a very practical sense. To obtain these principles, characteristics of various individual modes of heating are discussed and principles of combining them are deduced based on the behavior of the individual modes
Quality of prepared (processed) food can take a quantum leap through development of intelligent ovens. For automation in such ovens to succeed, cooking process and quality development need to be understood, predicted and controlled. As illustrated in Figure 1, the quality of foods, like texture (for example, sogginess) or flavor (such as through browning), is a multifaceted attribute resulting from chemical and physical changes that depend on such parameters as rates and uniformity of heating, and also moisture transport and loss which in turn depend, in a complex way, on process parameters such as power level, mode, and duration of heating. To have more control over quality, the oven needs to be predictable and programmable. Using several modes of heating simultaneously provides for an extensive degree of control over quality. Each heating mode affects quality parameters in a very different way. There is great potential in exploiting this difference, but it must 1st be understood.
Microwave heating is a multiphysics phenomenon that involves electromagnetic waves and heat transfer; any material that is exposed to electromagnetic radiation will be heated up. The rapidly varying electric and magnetic fields lead to four sources of heating. Any electric field applied to a conductive material will cause current to flow. In addition, a time-varying electric field will cause dipolar molecules, such as water, to oscillate back and forth. A time-varying magnetic field applied to a conductive material will also induce current flow. There can also be hysteresis losses in certain types of magnetic materials.
One obvious example of microwave heating is in a microwave oven. When you place food in a microwave oven and press the "start" button, electromagnetic waves oscillate within the oven at a frequency of 2.45 GHz. These fields interact with the food, leading to heat generation and a rise in temperature.
The efficiency of microwave heating depends upon the material properties. For example, if you place foods with varying water content in a microwave oven, they will heat up at different rates. A dinner plate may come out with some food on it that is very hot while the rest of it is still cold. Furthermore, the position of food relative to each other will also affect the electromagnetic field within the oven. That is why most microwave ovens have turntables to rotate the food and promote even heating.
More details here
https://www.comsol.com/multiphysics/microwave-heating
the heat in oven is transfer by the radiation between the materiel and heater.
Yes Ali Lateef the basic mechanism of heat transfer is radiation but also there is a small ratio of convection
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