The tag has no usage guidance.

learn more… | top users | synonyms

0
votes
1answer
55 views

What is “wrong” with this microwave?

Metal objects in microwave ovens are known to be somewhat dangerous. However, my microwave has the following label stuck inside: It seems to imply that this particular oven forbids heating drinks ...
0
votes
1answer
32 views

What do we mean by wavelength of any electromagnetic wave?

What do we mean by wavelength of EMW? Wavelength of oscillating electric field or the oscillating magnetic field? Or is it that both the electric and magnetic field waves have same wavelength? If ...
0
votes
1answer
21 views

Microwaving two products based on individual instructions

Suppose I have a cake, which has instructions to heat it for 60 seconds in the microwave. I also have some custard, which has instructions to heat it for 30 seconds in the microwave. For convenience, ...
0
votes
1answer
14 views

Electric fields with different frequencies, total intensity?

What happens when electric fields with different frequencies are combined? Is it possible to calculate the intensity of the total electric field? For a project, I need to simulate a brain treated ...
0
votes
0answers
20 views

Books on Spectral Jacobian

Can anyone point me a book to better understand "spectral Jacobian". I am studying X-parameters, I have the book X-Parameters: Characterization, Modeling, and Design of Nonlinear RF and Microwave ...
1
vote
0answers
38 views

Can I safely heat stainless steel 1-2 inch ball bearings in a consumer microwave? [closed]

I am looking to heat 1 or 2 inch stainless steel spherical ball bearings in a microwave. I would like the bearings to get to about 140 degrees F but not hotter. I have read that this should be fine as ...
0
votes
0answers
35 views

What are the properties of the electromagnetic radiation from a magnetron?

There are different modes of EM radiation. A bulb emits photons in a wide range of wavelengths and without polarisation. Radio waves are polarized modulated radiation. What is about the radiation ...
1
vote
0answers
37 views

wave propagation (refractive index gradient) [closed]

I have 2 questions and need some advice from you all. A $30\,\mathrm{km}$ microwave link operates at $4\,\mathrm{Ghz}$ using $4\,\mathrm{m}$ parabolic reflector antennas. the transmit antenna is ...
0
votes
0answers
110 views

Loaded Quality Factor

I came up with an expression for the reflected power of a resonator: $$\left| \Gamma \right|^2 = 1 - \frac{1-\left(\frac{\kappa - 1}{\kappa + 1}\right)^2}{1 + 4 \left( \frac{Q_U}{(\kappa + 1)} ...
1
vote
0answers
24 views

Microwave Farraday cage shielding

After a decade of using a microwave oven in my house I figured out I never cared to connect the grounding cable. So my question is regardless of electrical shock risk, does the Microwave Faraday cage ...
0
votes
1answer
69 views

Dodging Microwaves [closed]

I'm not sure if I'm just being paranoid or not but I'd like some explanation as to whether my fears are justified or not. With a normal microwave oven you can usually end the cycle early by opening ...
0
votes
0answers
36 views

What is the effective volume for TE011 mode in a cylindrical cavity?

Is the effective volume same as the volume of the cavity? I am not sure I understand the concept of effective volume.
1
vote
1answer
59 views

Light / TEM wave in a hollow waveguide

I'm cramming for my EMF exam, and a question came up: Light in free space is an example for a TEM wave, isn't it? (Maybe thats already my mistake) And we learned that in a hollow waveguide only TE ...
2
votes
0answers
24 views

In theory, Is it possible irradiate a blob of matter -for instance- with microwaves in order to that matter emit more energy than has received?

Suppose that you want coerce a block of matter to lose his energy. I mean thermal energy. This should be done by irradiation of more energy. The final thermal energy should be lower that the original ...
2
votes
1answer
520 views

If a microwave oven disk rotates to warm up food, why doesn't it go up/down/sideways?

This has been in my mind for a while... Well, actually everytime I heat any food with a greater amount of liquid in it: a microwave oven warms up food by inducing polar molecules in the food to ...
0
votes
1answer
50 views

Shape of metal to be heated in consumer microvave oven? [closed]

I tried to use a common 900 W microwave oven melt some alloy with low melting point (138 deg C, eutectic bismut/tin). The metal did not heat up, neither did the metal container, which makes me think ...
0
votes
1answer
79 views

Distance of electromagnetic waves based on frequency

I would like to ask your opinion regarding this matter: Based on the relation of frequency and wavelengths, the higher the frequency, the shorter the wavelengths and therefore the distance of travel ...
2
votes
2answers
273 views

Why does aluminium foil spark in the microwave? [duplicate]

I don't understand fully why aluminium foil sparks in a microwave oven? I think what is happening is the oven sets up an electric field, and the field induces a current in the foil (how?), and ...
0
votes
1answer
210 views

Electromagnetic cooling

Heat means stored kinetic energy in matter. Microwave owens and induction heaters works on increasing kinetic energy on matter. Is it possible to make inverse of this heaters like cooler. Can we ...
1
vote
0answers
172 views

Can a microwave oven induce an accumulation of static charge in food?

I often "touch test" microwaved food to see if it is heated up enough to my preference. In doing so, I sometimes notice the characteristic tingle of a static discharge between the food and my finger ...
0
votes
0answers
17 views

My microwave oven disrupts my bluetooth connection even when I'm 12ft away. Should I be worried? [duplicate]

I often wear bluetooth headphones that connect to my mobile phone. I work on my laptop in my dining room approx. 12ft away from the microwave oven and my mobile phone is usually in my pocket; ...
3
votes
0answers
65 views

Why do rings form on microwaved CD/DVDs?

Here's a microwaved CD. As you can see, the disc has been destroyed, but there are very clear circular rings bridged with lines. Why are rings formed when microwaving discs?
7
votes
1answer
1k views

Why when I put a teabag into microwaved water does the water fizz? [duplicate]

When I am in a rush, I will heat up water in a cup in the microwave for tea. I usually put the cup on high for 2 mins. When I put the teabag in, the water starts to fizz almost like it is ...
0
votes
0answers
37 views

Expanding the H and D field in orthogonal modes

Currently I am doing my bachelor thesis on the behaviour of Q-factors in 3D microwave cavities. One step in that process is to approximate the behaviour of the 3D cavity by comparing the cavity to an ...
1
vote
2answers
197 views

Does a source emitting visible light also emit infrared, microwave and radio waves?

I have a bulb which is hot enough to emit visible light and obviously it's hot enough to emit radiation which lies before the visible light temperature i.e. radio waves, microwaves, and infrared ...
5
votes
2answers
3k views

Why do we use microwaves in microwave oven?

We know that any object above absolute zero emits electromagnetic radiation. So hotter the object shorter the wavelengths. In the electromagnetic radiation spectrum radio waves has the longest then ...
2
votes
1answer
45 views

How come a current sheet of $J_s = J_0 \hat{x}$ produces plane wave solution?

Given in the picture. There is a current sheet $J_s = J_0 \hat{x}$. Supposedly Jo is not oscillating. So, how does this thing create a plane waves propagating away from the current sheet? Shouldn't ...
5
votes
3answers
2k views

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 ...
2
votes
1answer
98 views

Does humidity affect passage of microwaves?

Does the humidity level in air affect the passage of microwaves? I've heard people say water is radio opaque, so could a high humidity level lead to faster signal degradation? As an example, would ...
0
votes
1answer
43 views

Energy variations of cosmic background radiation

Has anyone been able to measure a difference in the energy density of Cosmic Background Radiation in a gravity well compared to zero gravity?
3
votes
2answers
104 views

Microwave oven and heating my sons milk

I heat up my sons milk in the microwave... I use the same volume all the time and always punch in 42 seconds (on high) and his milk comes out the perfect temp every time. However, sometimes he ...
0
votes
1answer
138 views

Why would a sweeping LIDAR or RADAR beam not produce an artificial Doppler shift?

Assuming a bi-static Radar or LIDAR with a stationary transmitter and a stationary target and a stationary receiver, with a sweeping RADAR/LIDAR beam reflecting off a stationary target: Why would the ...
0
votes
1answer
70 views

Dielectric heating - does EM field transfer energy to polar molecules?

In AC field, polar molecule are trying to align with external field. At high freguencies, changes of field are so quict, that molecules cannot align with it. This leads to increasing kinetic energy of ...
12
votes
3answers
460 views

Is it really possible to “discover” the speed of light with a microwave oven?

I've seen a number of sites/videos online that describe a method for measuring the speed of light, using a microwave oven and a chocolate bar. For example, this video on youtube. The basic idea is to ...
1
vote
0answers
58 views

I need to remove water from a system [closed]

I work in an industry and I need to remove water from a system. The scenario: There is a washer and a blower on a conveyor belt. The item being washed is plastic (not sure what type) and can't be ...
0
votes
1answer
155 views

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 ...
18
votes
2answers
4k views

How do microwaves heat moisture-free items?

Today I learnt that microwaves heat food by blasting electromagnetic waves through the water molecules found in the food. Does that mean food with 0% moisture (if such a thing exists - dried spices?) ...
2
votes
2answers
413 views

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 ...
0
votes
1answer
103 views

If halving signal strength is only a 3db drop, why can't cell phones be much lower powered?

My phone can receive a signal that's -90dBm. That's roughly one-billionth of a milliwatt. Cutting a signal's strength in half only drops the signal by 3dBm. Apart from slightly higher range, is there ...
1
vote
2answers
647 views

2.4Ghz microwaves have a 12cm wavelength. How do microwave ovens leak radiation, since any gap in the shielding is much smaller than that wavelength?

I've read (I think on wikipedia, but I can't find the reference) that microwave oven leakage is often due to faulty seals on the door. Given that any gap in the door is going to be far smaller than ...
3
votes
2answers
2k views

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 ...
1
vote
1answer
24 views

Generator phase noise influence on its averaged signal

I need to estimate averaged signal of a generator with known phase noise and the amplitude noise can be neglected. The averaged signal of the generator is expressed as: $$ \langle A\exp{i(\Omega t + ...
0
votes
0answers
35 views

Why can microwave (in microwave oven) heat the food but wifi can't? [duplicate]

As far as i know, microwave (used in microwave oven) and wifi all operate on the same frequency, but why microwave can heat the foods while wifi wave can't?
11
votes
4answers
2k views

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? ...
0
votes
1answer
60 views

Use microwave cavity in atomic clock

In most of the papers regarding atomic clocks, the author talks about a microwave cavity. In this box, all the unwanted frequencies of the electromagnetic radiation are absorbed and the other ...
2
votes
1answer
326 views

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 ...
0
votes
2answers
245 views

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 ...
7
votes
2answers
551 views

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 ...
9
votes
4answers
484 views

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 ...
2
votes
2answers
278 views

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 ...