My understanding is that microwave ovens produce microwaves at a set frequency (say 2450 MHz). So if there is one set frequency, what is the difference between using a power setting of 600W or 1200W with a microwave digestion oven? Are there twice as many microwaves produced with 1200W than with 600W? How and why does 1200W heat something up faster than 600W?
I do not mean using 50% power of 1200W, for example, when the magentron would cycle on and off. I understand the mechanism of heat produced from microwave energy but do not understand how this relates to the wattage setting on a microwave digestion oven.
First, power and energy are different things. Think of energy as the thing you can pick up and take with you, like water in a bucket. Power is how fast that energy is being used, like how fast the water is being poored from the bucket.
To answer your question, power of a microwave has to do with the wave's amplitude, or "size" of the wave. The waves have a certain strength, like waves at a beach. Tiny ripples do not carry much power and you can barely feel them. Bigger waves carry more power and can knock you over. They can both be at the same frequency, they just have different amplitudes. Amplitude determines how much power a wave is carrying.
Energy has to do with how long you run the microwaves. It will take more energy to run the microwaves longer. This is just like the water in a bucket analogy. A low power microwave running for a long time will deliver as much total energy to something as a powerful microwave running for only a short time. In scientific terms, we usually call this "dose." Dose is power multiplied by time and has units of energy (joules).
Hope I answered your question!
power density=power transmeter*gain of transmitting of antena/ 4+3,14+distance from anntena
You guys have forgotten the basic physics. Power is the time rate change in energy. That applies to all situation , microwaves include. Or if you refer to the unit time then energy=power. No difference
A Joule is a unit of energy. Energy can make something a bit hotter. One Joule will make 1 gram of water about 1/4 degree centigrade hotter. One Joule per second is a watt. To heat 125 grams of water 80 degrees takes about 42,000 Joules, or 42 kJ. You can do this in about 35 seconds with 1200 watts (1200 Joules per second) or in about 70 seconds with 600 watts. It will take a bit longer than this because some heat will escape into the air and the cup.
Microwaves exist as electric and magnetic fields in the air in the oven, and in the water, and in currents on the oven walls. For twice the power, the fields, and the currents, are 1.4 times as large. Turning it on and off, by pulse width modulation, or seconds at a time as mine does on defrost, changes the average power so makes it take longer to get to the same total energy input which means roughly the same temperature change (for the same amount of water, for example).
When the water gets to 100 degrees any extra microwave energy just goes to turning water into steam (which isn't necessary) and replacing lost heat. Replacing lost heat doesn't require as much energy per second as heating things up so lots of recipes suggest gaps in the microwave cooking after a time when everything should be up to 100 degrees.
With 1200W, the average radiation intensity or power density falling on the object would be twice than that at 600W, therefore the energy transferred to the object inside microwave oven would be same at 1200W and 600W if the time for which Microwave Oven is ON is half at 1200W than at 600W.
Microwave ovens (magnetrons or any other sources of microwaves) produce electromagnetic field oscillations radiated in an open space (or in microwave oven itself). Electromagnetic field is characterized by amplitude of electric field component oscillating at some frequency (which is 2.45 GHz for microwave oven). The higher is the amplitude of the oscillating electric field, the higher is microwave power, which is a pointing vector, https://en.wikipedia.org/wiki/Poynting_vector#:~:text=In%20physics%2C%20the%20Poynting%20vector,first%20derived%20it%20in%201884. .
By such a way, there is a direct relation between electric field amplitude and microwave power.
Microwave energy is an integral of the microwave power over some period of time.
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