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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33
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2answers
21k views

How can wifi penetrate through walls when visible light can't?

I did search the question on Physics S.E considering it would be previously asked. I found this How come Wifi signals can go through walls, and bodies, but kitchen-microwaves only penetrate a few ...
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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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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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6answers
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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 ...
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1answer
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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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4answers
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Why do we use microwaves in microwave oven?

We know that any object above absolute zero emits electromagnetic radiation. The hotter the object, the shorter the wavelengths. In the electromagnetic radiation spectrum, radio waves have the longest ...
14
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1answer
5k views

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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2answers
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Why do microwave ovens use radiation with such long wavelength?

According to Wikipedia: Consumer ovens usually use 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in). Typically, I put the dish inside the oven in its center. I suspect most people ...
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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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2answers
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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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0answers
257 views

What is the lowest energy atomic transition ever detected and identified?

In this concise and insightful answer to Which is larger, all known, bound nuclear energy levels, or known, bound atomic energy levels? it was pointed out that atoms can have an extremely large (...
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1answer
900 views

The "watering hole" frequency versus microwave oven frequency

I recently learned about the "watering hole," a group of frequencies between 1.42 and 1.66 GHz. I also read that microwave ovens operate at 2.4 GHz. If 21 to 18 cm (1.42 to 1.66 GHz) is the resonant ...
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If visible light has more energy than microwaves, why isn't visible light dangerous?

Light waves are a type of electromagnetic wave and they fall between 400-700 nm long. Microwaves are less energetic but seem to be more dangerous than visible light. Is visible light dangerous at all ...
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What makes cheese so effective at absorbing microwaves?

Whenever I put a meal in the microwave which contains cheese, why does the cheese get hot before the rest of the meal is heated through?
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Why is Microwaved mac & cheese burnt where they touch?

After reheating cold about 1.5 oz. of Annie's Mac & Cheese shells for 15 seconds on high power in the microwave, the mac & cheese was burnt black only at certain points where the pasta is ...
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In a microwave oven, why do smaller portions heat up faster?

Sorry for brevity, but what is the exact physics explanation of why smaller quantities placed inside a microwave oven heat up faster than when you place a larger quantity of a similar material inside?
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4answers
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Is it possible to shield a camera so as to record from the inside of a running microwave oven?

Would it be possible to create shielding for a camera, allowing it record food being cooked from the vantage point of the inside of a consumer microwave oven without the camera being damaged? ...
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5answers
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How come Wifi signals can go through walls, and bodies, but kitchen-microwaves only penetrate a few centimeters through absorbing surfaces?

The only difference that I know of between kitchen microwaves and WiFi signals is how much power is pumped through them. Why is it that WiFi signals, being 1000 times weaker can travel so much ...
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1answer
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How can electromagnetic waves reach a cell phone in Faraday cage?

is there any way to make electromagnetic waves reach a cell phone in Faraday cage although conductor surround cell phone everywhere? can we pass current through conductor to make charges move as a ...
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2answers
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Why does plastic wrap grow, then shrink, then grow again when microwaved?

The other night I was reheating a bowl of leftovers in the microwave. There was a fair amount of liquid in the bowl, so I covered the bowl with plastic wrap when I put it in the microwave. When I put ...
12
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2answers
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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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2answers
732 views

How come a mobile phone signal is blocked by aluminium foil, but Wi-Fi gets through?

Major puzzle for me. I have done a demonstration in lectures for years now, where I show that a mobile phone call can be blocked by wrapping the phone in a single sheet of standard Aluminium kitchen ...
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7answers
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Will a microwave heat sand?

I want to cook Turkish coffee on heated sand at school. I have difficulty accessing some easier method of heating, so I was going to try to heat sand in a microwave. It was then pointed out to me that ...
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1answer
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Why does the food in the microwave heat up but the bowl doesn't?

I put a 1/4 inch thick clear glass container into the microwave with a plate on top and put it in for almost 5 minutes (there was lots of soup). When It came out the soup was really hot but I could ...
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1answer
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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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3answers
592 views

Can radio waves be harmful to us?

I was studying about Microwaves and their action on water molecules in heating up the food. This all is probably due to Microwaves have wavelength such that it can be absorbed by water molecules (am i ...
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2answers
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What would a graph of temperature increase of a cup of water in a microwave look like?

My lunch had been in the microwave for a minute or so, and I was wondering if I took it out 10 seconds early, would the amount of temperature it increased in that 10 seconds be more significant, less ...
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1answer
114 views

How do microwave kilns work?

I have recently been doing some research into the working principle of a microwave kiln, and have run into a few things that continue to confound me. The first of which being that the devices ...