Questions tagged [microwaves]

Microwaves, broadly defined, are electromagnetic radiation with wavelengths ranging from one meter to one millimeter; or with frequencies between 300 MHz (100 cm) and 300 GHz (0.1 cm). This range includes both UHF and EHF (millimeter waves) and the entire SHF band (3 to 30 GHz, or 10 to 1 cm).

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Why can't microwaves use molecules' dipole moments to cool?

My understanding is that microwaves use the dipole moments of water molecules to heat things. The microwaves resonate with the dipole moment, and add energy to the system. How exactly does the ...
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Does the cell phone make dipole particles in our body dance the same way Microwave oven does in food

I am a non-physics person trying to wrap my head around some EM radiation facts. Please help me with this. I have read about Dielectric Heating on Wikipedia. And watched quite a few videos on ...
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How can we detect cosmic background radiation?

From what I understand, CMB is the left over radiation from the Big Bang. As all matter, including the Earth, was made during the Big Bang and then as the universe expanded that matter/energy got ...
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Can we detect whether food has previously been heated in a microwave oven?

An acquaintance told me that she refuses to eat microwaved food because she read that the microwave changes the molecules of the food somehow. Her statement is vague and her sources are dubious but I ...
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Heating effects of microwaves

I understand the heating effect(dielectric heating) of microwaves. This heating is caused by using a frequency of 2.45 GHz and this is the same frequency at which Bluetooth works and the L and S ...
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Is preheating plates in microwave dangerous? If so, why?

My understanding of microwaves was that due to the high frequency they are easily absorbed into any material. The more "loose" the material, the easier the absorption. I know it's dangerous to let ...
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Effects of microwaves on optical properties of human eye [closed]

I have read a long series of paragraphs on wiki. Previously I thought that microwaves are not harmful to living beings but Wiki does not claim this explicitly. while doing an experiment in my college ...
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Microwaves and metal poles

I have an experimental setup like so: And if one looks closer at the lens, there are metal poles near the bottom of the lens (the extensions of the stands beyond the clamps) that are obstructing the ...
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Does the cavity magnetron in a microwave oven produce x-rays?

It seems like it should due to bremsstrahlung, since we're talking about electrons with 5-7KeV of energy slamming into the walls of the device, but I've found no information about this online, so I'm ...
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How can laser communication be faster than microwave?

My textbook states that "Laser communication is much faster than microwave communication." But, how can that be? Both are electromagnetic waves with different frequencies but, how can the speed be ...
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Why do (most) metals cause problems in a microwave oven? Which metals (if any) don't? [duplicate]

Most of us have seen microwave ovens with metal racks or shelves, which challenges the common notion that you can't (safely) put metal in a microwave oven. What's going on here? Is it a matter of ...
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Microwaves and state of matter

Does the heating efficiency of a microwave oven depend on the state of matter that it heats? If yes, how?
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Why do some food items leak water on heating in microwave?

As seen in photo (delicious gulab jamun) after heating a certain food item that contains water, simply leaks it out. The sugary syrup seen in photo was not present with the sweets before heating but ...
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Plane wave reflection

Using the plane wave reflection equation... $$1-R=T \space ?$$ I cannot find the symbol of reflection constant so i will call it as "L" 1+L = T What ...
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Impossible microwave interference?

I was doing a microwave experiment with the following set up: there is a Gunn diode which emmits microwave radiation and a receiver (both work with polarised light). The strange thing is that when I ...
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Why doesn't visible light generate sparks in aluminum foil when microwaves do?

When aluminum foil is placed in a microwave, I see sparks generated by what I assume is dielectric breakdown. However, if I put aluminum foil in visible light (assuming the same intensity), there are ...
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Does a domestic microwave work by emitting an electromagnetic wave at the same frequency as a OH bond in water?

I was told once that microwaves work by exciting water molecules in food. Also that this worked because the frequency in the microwave was the same as that in the bond between Oxygen and Hydrogen in ...
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Why do metal objects in microwaves spark?

I heard that electrons accumulate at points on metals, and this clearly explains the arcing phenomenon, but how does a microwave make an electron imbalance on the fork?
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Do Microwave oven heating times grow linearly with Wattage? Calculating optimal heating time

So this is a completely random and trivial question that was prompted by looking at my microwave oven and the back of a TV dinner and my google searching failed to produce a meaningful answer so ...
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How could we see microwave radiation with our eyes?

A few years ago I read a short little article about how big our eyes would have to be to observe microwaves (or any long-wave radiation for that matter). I don't remember enough about the article, or ...
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Microwave oven heating time

It's logical to think that the time it takes a microwave to heat the food would be proportional to the mass heated. But since a microwave is based on dielectric heating, I think that if you increase ...
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What properties make a good barrier for microwave (oven) radiation?

Suppose I have plenty of food I want to heat (which will provide load) in the microwave, and one item I don't want to heat. What properties would make a material a a good shield, to reduce or prevent ...
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Are normal light waves more dangerous than WiFi radiation? [closed]

I'm getting sort of tired of all the "wireless hysteria", so I thought this might be a nice comment. To the extent of my knowledge, WiFi uses microwaves, which have a lower frequency and hence carry ...
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Why are different frequency bands used in different countries?

Why are different frequency bands used in different countries despite ITU's effort for a common frequency band use? There's got to be a reason behind this. For instance, U.S.-based Verizon Wireless ...
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Could we really charge metal plates using microwaves?

While skimming through Dielectric heating, I read that they use microwaves to charge the plates. How do they do that?
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Does a microwave resonantly excite the rotational levels when cooking?

Wikipedia states there is no resonance absorption, but says at the same time that the molecules are oscillating like dipoles, which is kind of the same if you are exciting the rotational levels ? The ...
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How does the grid on the microwave oven window prevent microwave radiation from coming out?

If I look through the microwave window I can see through, which means visible radiation can get out. We know also that there is a mesh on the microwave window which prevents microwave from coming out. ...
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Can microwaves affect WiFi?

I listen to the radio via my iPad with wifi. When I switch the microwave oven on, the radio cuts out. When the microwave oven is finished, the radio comes back on. (This is 100% reproducible!) So - ...
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Could cell-phone radiation cause cancer?

It is very crucial that I ask whether it could and not whether it does. I do not mean to be the least controversial. To my surprise, having read "Physics for Future Presidents" by Richard Muller last ...