Skip to main content

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).

Filter by
Sorted by
Tagged with
0 votes
0 answers
95 views

Distance needed for visible light to be cosmologically redshifted to microwave

What distance will it take for visible light to become a microwave due to cosmological redshift? I'm not sure how to calculate this, as I'm never good at complex math. I tried googling but didn't find ...
X3R0's user avatar
  • 109
15 votes
4 answers
8k views

If microwave ovens run at 2.4 GHz, what is the long-term effect on living tissue of exposure to this frequency, but with a thousand times less energy?

Very low power electromagnetic waves with a frequency of 2.4 GHz can't cook anything. That's obvious, despite the heating effect such radiation has on water. However, what if such an object containing ...
Mesijé vopřenej Vo zeď's user avatar
1 vote
2 answers
99 views

Physics of microwave oven

I am looking for a definitive discussion of the physics of microwave oven - I mean I would like to see actual evidence in favor of this or that explanation, rather than just popular physics/...
Roger V.'s user avatar
  • 60k
10 votes
5 answers
3k views

Why does microwave take more time to heat more food?

As I understand, a microwave works by generating an electromagnetic field. As food enters this field, waves will transfer energy to those food particles that are intercepted by waves, and those ...
Maurice's user avatar
  • 101
2 votes
1 answer
35 views

In magnetrons, is it the accelerating electrons or alternating fields within the anode that produce the microwaves?

Doing a report for a school project and want to get to the bottom of the radiation source within a microwave oven: According to Maxwell's equations don't the accelerating electrons (accelerating ...
Hearn's user avatar
  • 21
3 votes
0 answers
64 views

Can cell phones send message in the elevator?

From Gauss's theorem, a closed, hollow conductor shields its interior from fields due to charges outside, but does not shield its exterior from the fields due to charges placed inside it. So my ...
Yuan Fang's user avatar
  • 275
1 vote
0 answers
35 views

How long to put Silica gel in microwave oven?

I have a 800 W microwave oven and want to dry some silica gel packages (each labeled with 10 g and sealed in paper mantling). The silica gel is colorless and seems to be of the kind of silica gels ...
user7468395's user avatar
-1 votes
2 answers
80 views

What's the difference between the different kinds of EM waves?

I am an A-level student. We have traditionally been taught that different types of EM waves exist only between certain ranges of wavelengths and frequencies. However, I learned that electromagnetic ...
Haram Tanveer's user avatar
0 votes
1 answer
101 views

Microwave oven efficiency and conservation of energy

Wikipedia says that microwave ovens can be around 50-64% efficient at converting electricity into microwaves. Where does the energy lost at this stage go? And how much of the energy that is ...
Karl's user avatar
  • 103
1 vote
0 answers
54 views

How to practically generate longitudinal waves in a plasma

It can be read almost everywhere that plasma is the best convertor of transverse waves to longitudinal waves. I'm not much interested in the theory here. Rather, I would like to know how to do it in a ...
MikeTeX's user avatar
  • 487
0 votes
0 answers
49 views

Why can $Q$ be calculated by $f_0/f_{FWHM}$?

I found this expression for the reflection signal of a microwave cavity: $$ |\Gamma|^2(f) = 1-\frac{1-\Delta M}{\left(2Q\left(\frac{f}{f_0}-1\right)\right)^2+1}, $$ with $f$ the frequency, $f_0$ the ...
LeendertMeneer's user avatar
0 votes
1 answer
27 views

Microwave waveguide position is not symmetric with respect to the center of the cavity

I am using a Panasonic microwave oven for some experiments. I found that the waveguide is not placed centrally on the side wall. The waveguide flap is closer to the back wall of the cavity than it is ...
yds1798's user avatar
0 votes
1 answer
63 views

How to measure time varying electric field strength accurately in space and time?

I would like to know of any techniques that can be used to measure the electric field strength precisely and accurately in both time and space. I know that there will be physical/ practical ...
Christian's user avatar
  • 113
0 votes
0 answers
70 views

When temperature is only caused by translational kinetic energy, why does microwaves heat water by rotation? [duplicate]

I thought microwaves causing water molecules to rotate, thus raising the temperature of my food but temperature isn't caused by rotation or vibration degree of freedom: We also pointed out that ...
iwab's user avatar
  • 211
0 votes
1 answer
62 views

Why do some microwave meal instructions violate the 'Specific Absorption Rate' rule?

Do Microwave oven heating times grow linearly with Wattage? Calculating optimal heating time states that the product of the microwave power and cooking time should be constant. However, some meals ...
Gnubie's user avatar
  • 1,879
-1 votes
2 answers
221 views

Is it possible for microwave beam to pass through non-metalic materials?

Greetings fellow physicists. I have some questions about the ability of different electromagnetic waves to pass through materials that I hope you can clarify. It seems that microwaves can go through ...
Hooman Puyandeh's user avatar
1 vote
0 answers
43 views

Why does my microwave turn on other battery powered electronics?

Situation: I have a 8-10 yr old LG microwave in a small alcove built into the cabinetry of our kitchen counter. I have a pretty cheap Bomata battery powered coffee scale that I store on the countertop ...
Gronk's user avatar
  • 111
0 votes
1 answer
37 views

Effective permittivity of multiphase system

I am simulating the microwave heating of a packed bed of solid spheres. This consists of a discrete phase made of the solid spheres and a continuous phase in between. In order to simplify the problem ...
cosmogato's user avatar
1 vote
1 answer
151 views

Is the argument of zero tangential field components in wave guide walls a fallacy? Or: How EM waves "magically" find their correct transverse modes

I just came across a nice answer on Quora, explaining visually how wave guide modes can be constructed from the condition of zero tangential fields in the wave guide walls. In mathematical terms, this ...
srhslvmn's user avatar
  • 181
0 votes
1 answer
101 views

Is there laser operating at megahertz?

I have tried to find a laser with working frequency at megahertz by Google but failed. Is there exist one?
Hunter's user avatar
  • 1
1 vote
3 answers
3k views

Why does a microwave's faraday cage block microwaves but not larger wavelength radiowaves?

I read that the Faraday cage on a microwave door prevents the microwave radiation from escaping the microwave because the wavelength of the microwaves is "too large to fit" through the holes ...
Cole Pearson's user avatar
1 vote
1 answer
79 views

How does 3cm microwave pass through a 0.5 cm grating?

This YouTube video prompted a question. If the wavelength of the PASCO microwave generator is about 3 cm, how do we explain that a significant portion passes through a 1/2 $cm^2$ screen? I have a ...
daniel's user avatar
  • 590
-1 votes
1 answer
80 views

What is radio frequency microwave energy used for? [closed]

Yesterday, the X-37B landed in Florida after 3,774 days in space orbiting earth since 2010. It was said to be transmitting radio frequency microwave energy towards earth for experimentation. What is ...
JustBeingHelpful's user avatar
1 vote
1 answer
2k views

Why does my microwave oven affecting Bluetooth signals? [closed]

Today morning I observed something interesting while I was listening to music with Bluetooth earphones. I connected earphones to my mobile phone that was lying almost 20 feet away . Music was of ...
McLovin's user avatar
  • 111
6 votes
0 answers
75 views

Does 5G affect your physics experiment?

Our institution wants to lease a nearby roof for a 5G mast. Has anyone experienced the installation and operation of telecoms infrastructure - particularly 5G - significantly affecting physics ...
NLambert's user avatar
  • 537
0 votes
1 answer
95 views

Need the (frequency dependent) dielectric permitivity of quartz

I have desperately googled to find a table or a graph for the complex dielectric permitivity of quartz (e.g. fused quartz), as a function of frequency, at room temperature. I am mostly interested in ...
MikeTeX's user avatar
  • 487
3 votes
1 answer
70 views

In a ion source, how do we make the ions get out of the cavity?

Ion sources are devices that allow creating ion beams (e.g. argon ions) and to project them outside the device, for example to be further processed by a particle accelerator, or to irradiate materials ...
MikeTeX's user avatar
  • 487
11 votes
3 answers
3k views

If we have a cosmic microwave background should't we also have a cosmic radio wave background?

I'm a layman in physics, but here is what I understand: What we see in the sky with naked eyes is a map of electromagnetic waves in the frequency visible to the human vision. But that kind of ...
Werex Zenok's user avatar
0 votes
0 answers
30 views

Coupling ion ray with a EM wave and penetration depth

Ion sources are devices that allow creating ion beams (e.g. argon ions) and to project them outside the device, for example to be further processed by a particle accelerator, or to irradiate materials ...
MikeTeX's user avatar
  • 487
1 vote
0 answers
122 views

Relation between Radiance and Surface power density (i.e poynting vector intensity)

I am attending a microwave remote sensing course and I have same problem to understand the relation between the radiance and the intensity of poynting's vector. The radiance is defined as: $L(\theta,\...
Marco Toni's user avatar
0 votes
1 answer
163 views

Do microwaves only make water spin? Can microwaves spin single atoms?

I’ve been reading how microwave ovens cook food by spinning water molecules and was wondering if water is the only molecule that can be spun using microwaves, possibly by raising or lowering the ...
user11937382's user avatar
1 vote
1 answer
115 views

Does microwaves nevertheless pass through smaller slits?

It is known that the Foucault currents prevent the microwaves to leave a microwave oven (MWO). The waves can not pass tru several times smaller openings than their wavelength because the grid of the ...
Mercury's user avatar
  • 651
0 votes
1 answer
303 views

What would happen on an atomic level to mercury in a microwave?

I'm not sure why I was thinking of this, but I did and I couldn't think of an equivalent physical model to relate microwaved liquid Mercury to. Polar substances are heated by dielectric heating, the ...
AncientSwordRage's user avatar
1 vote
1 answer
184 views

Microwave turntable absorption

I have heard that microwave turntables absorb microwaves when there is very little load in the cavity, which limits the reflection to the magnetron. Will this also limit the leakage radiation from the ...
Steve's user avatar
  • 11
0 votes
1 answer
140 views

Why wire grid polarizers do not re emit absorbed radiation both ways?

The wikipedia page on polarizers states about wire grid polarizers that : "Electromagnetic waves that have a component of their electric fields aligned parallel to the wires will induce the ...
Manu de Hanoi's user avatar
0 votes
1 answer
23 views

Frequency upconversion of pulses shorter than 1 IF period

I have a rather elementary frequency upconversion/mixer question, perhaps so simple that it does not warrant a real question but rather just a reference to a website/tutorial (that I have not been ...
user129412's user avatar
  • 1,521
0 votes
1 answer
187 views

Is water thermolysis via microwave heating feasible?

Can water molecules be heated enough (2500°C? 3000°C?) to be separated into hydrogen and oxygen by thermolysis via a microwave emitter? I've searched around but it appears this hasn't been researched? ...
Sebastián Vansteenkiste's user avatar
3 votes
6 answers
814 views

Why do microwave ovens need to have a resonant cavity?

Why is it considered necessary for the microwave oven to be a resonant cavity? If it wasn't resonant then the energy wouldn't have anywhere to go but in the food as well. So I don't understand the ...
Manu de Hanoi's user avatar
1 vote
2 answers
282 views

Is the accuracy of atomic clocks about engineering limits?

I read that a microwave with specific wavelength is shone on a bunch of atom to make them change energy state from ground to excited state, then they measure this difference in energy to determine its ...
user6760's user avatar
  • 13k
14 votes
7 answers
5k views

Microwave inside-out cooking true/false

The wikipedia article on microwave ovens says Another misconception is that microwave ovens cook food "from the inside out", meaning from the center of the entire mass of food outwards. It ...
Erhannis's user avatar
  • 327
-1 votes
1 answer
77 views

How can effect of electromagnetic radiation on human sperm be explained physically? [closed]

I am not sure if this question belongs here. If it doesn't belong here, feel free to remove it (and maybe tell me where to post this instead?). I have been researching the question of whether ...
Aaronmacaron's user avatar
11 votes
1 answer
1k views

Why is my bluetooth signal able to exit my microwave?

I was shopping for a bluetooth meat thermometer. Since this device would also be used in my combo (conventional and microwave) oven, which is shielded for microwaves, I expected the device to not work....
Jeffrey's user avatar
  • 1,003
0 votes
1 answer
84 views

What implies that transverse EM fields satisfy Laplace's in TEM waves?

I am reading Pozar's Microwave engieering. When explaining the TEM waves (pag98 4th edition) he defines $\bar{e}(x, y)$ as the transverse electric field. He proves that $$\nabla_{t}^{2} \bar{e}(x, y)=...
DamyHao's user avatar
  • 71
2 votes
0 answers
91 views

If I made a double slit using microwave oven door, do I get an interference pattern?

Imagine the following setup: A microwave oven door with 2 holes big enough for the wavelength of microwave to pass through, high power magnetron as the source of microwave and wall of metal to produce ...
user6760's user avatar
  • 13k
1 vote
1 answer
24 views

Can lenses and mirrors be described in terms of beamwidth and directivity?

As a first background, I am an Electrical Engineer with experience in antennae design for microwave bands. Lately, I have been interested by optical devices, and I notice one strange phenomenon: when ...
user3141592's user avatar
0 votes
2 answers
178 views

When an electrical field is generated inside a Faraday cage (say as in a microwave) does the cage act as a reflective surface to amplify the field?

I am familiar with the concept that electrical fields within a Faraday cage do not extend outside of the cage and that electrical fields generated outside do not extend into it. My question is -- when ...
plumpy's user avatar
  • 1
-2 votes
2 answers
200 views

Building a "stelaser" - a star-powered maser network that distributes free global electricity. Why and Why not?

I wish to design a Space Based Power platform that delivers microwave power from space. This approach has been criticized (famously by Elon Musk), because converting sunlight to electrons to ...
adamwong246's user avatar
15 votes
4 answers
5k views

Why do microwaves penetrate flesh when visible light does not at the same intensity?

I understand why microwaves penetrate flesh, it has been answered before here, but in the most answers it was mentioned that although microwaves have less energy per photon when compared to visible ...
Samyak's user avatar
  • 177
0 votes
1 answer
65 views

Scattering parameter oscillation

Why does scattering parameter $S_{11}$ for a two port measurement with a simple cable oscillate with frequency?
SR_00's user avatar
  • 9
0 votes
0 answers
54 views

Microwave effect

I'm new to the forum. I state that I am a technician and I have to deal every day, even with various types of radar, but I am not only concerned with this. I found out on the web about the danger of ...
Samyt 's user avatar
  • 11

1
2 3 4 5 6