# 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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### 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 ...
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### 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 ...
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### 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/...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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?
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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### 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 ...
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