Why do microwave ovens make such a distinctive humming sound? | AskScience Blog

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Monday, September 9, 2019

Why do microwave ovens make such a distinctive humming sound?

Why do microwave ovens make such a distinctive humming sound?


Why do microwave ovens make such a distinctive humming sound?

Posted: 08 Sep 2019 12:47 PM PDT

When I look this up the only answers I come across either talk about the beep sound or just say the fans are powerful.

But I can't find out why they all make the same distinctive humming noise, surely it should differ from manufacturer to manufacturer? Surely some brands would want to use quieter fans?

submitted by /u/thinvanilla
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Allowed electron orbits seem odd and purely a mathematical construction. Are they just theory but reality gives more laxitude to where an electron might be?

Posted: 09 Sep 2019 04:18 AM PDT

In A Brief History of Time, Hawkins explains the allowed orbits by saying only integer multiples of an electron's wavelength are allowed, otherwise after a certain number of orbits the electron's wave will destructivley interfere and the e- will disappear and you restrict your solution-space to discrete allowed orbits.

Does this mean we limit ourselves further to electron energies that have wavelengths longer than or equal to their orbital circumference so they can intefere? If the wavelength is shorter than the circumference would we not have a band of orbits which will never destructivley interfere and hence not limit ourselves to the simpler situation of discrete energy levels for the e-?

Also, as a mathematician, if space around the e- is compact these allowed orbits (to me) represent the limit points of allowed orbits and that in the real world you would have a band of 'effectively' allowed orbits which would be stable for long periods of time without ever collapsing into the nucleus or flying out into space.

The band might be small, but a band of any size at all would give an uncountabley infinite number of possible orbits in the physical world, hence when you come to describe the e- in the world of quantum mechanics you can't use the simplification of discrete energy levels which will messes up their representation when expressed as vectors.

submitted by /u/stinkers87
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What does oxygen production in a tree scale better with? The amount of leaves or the who biomass of the tree ?

Posted: 09 Sep 2019 07:46 AM PDT

Would a small tree with the same amount of leaves produce less oxygen than a bigger tree(more tree, more energy required, more efficient use of leaf surface area)?

EDIT: Whole* biomass in title, ffs...

submitted by /u/si3rra_7
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How do fans cool a room?

Posted: 08 Sep 2019 09:05 PM PDT

How can a fan, put in a hot room and surrounded by hot air, take that still air and cool it through acceleration alone? Why doesn't the room stay just as hot but with more hot air circulating? There is no chemical refrigerant used, so I don't understand where the heat transfer occurs.

submitted by /u/KidAardvark24
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Is it possible to create an artificial lightning/thunder on a very small scale? If so, how?

Posted: 09 Sep 2019 06:45 AM PDT

If you somehow condensed all of the sunlight that hits Earth into a beam 1cm in diameter, how hot would that beam be?

Posted: 09 Sep 2019 02:35 AM PDT

How does Isopropyl Alcohol interact with Passivated Stainless Steel?

Posted: 09 Sep 2019 05:59 AM PDT

I have been doing some research into stainless steel passivation as it relates to my field of work, and as it is still new to me, I am trying to know what to avoid when it comes to my part in handling such things.

Today I was cleaning some stains from said passivated steel, and when it occurred to me that I didn't know how this would interact with the passivated layer (chromium oxide?). I began to worry that I may have damaged them unwittingly, and I still don't know if that's the case.

So will this have caused damage to the parts? Also any info that may be relevant to passivation in general, and safe handling, would be of great interest.

submitted by /u/questions178
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Could you capture random microwaves flying about the place and turn them in to energy (or is there not enough random microwave ebergy flying about)?

Posted: 09 Sep 2019 04:11 AM PDT

Sorry, I'm not well versed in this as the title suggests.

But would it be possible to reverse a micrwave's mechanics in some way as to be able to capture microwaves and generate electricity?

Does the sun- for example- give off microwave radiation that we cant capture with solar cells, but that we might capture with some massive horn that concentrates these rogue microwaves?!

I have no idea, but I suspect someone here does. Any advice or info is much appreciated.

submitted by /u/Trynottobeacunt
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How much does the annual flu shot in the U.S. actually help given that it only immunizes against a handful of strains?

Posted: 08 Sep 2019 04:04 PM PDT

(I am not an anti-vaxxer or anything like that, I'm just curious.)

submitted by /u/gcross
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Conceptually, what is the cross-section in Quantum Field Theory?

Posted: 09 Sep 2019 01:02 AM PDT

(Reposting, because I forgot to add a question mark in the title)

After finishing my introductory Quantum Field Theory course, I don't feel like I'm actually grasping the concept of the cross-section very well. I understand that it is related to the matrix element and probability of an interaction, but I don't see the connection with cross-sectional area.

We used Peskin&Schroeder as a reference, and I found their explanation of the concept very vague.

submitted by /u/Akaleth_Illuvatar
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After putting down a hot plate, why does the pain persist, is it because of swelling?

Posted: 08 Sep 2019 03:49 AM PDT

I just held a pretty hot plate of food, but after putting it down, my fingers are still stinging a little, with slight swelling.

I get that because it's hot, the heat receptors in my fingers have sent a signal to my brain: is it correct to say that my brain then processes this and 'says' that it is dangerous, so I feel pain because I'm being made to stop holding the hot plate?

Are there different receptors for 'okay temperatures' and 'not okay' like there are for cold and hot relative to our body temperatures? Do these temperatures change? Like chefs have 'abestos hands' is this a receptor/nerve thing (one post suggested the nerve endings here may have been damaged), or is it really thickened skin, or is this a mental thing?

Then, after I put down the plate, I notice a little swelling on some of my fingers. Apart from the temperature differences across the bottom of the plate, does acclimatisation to the high temperatures also impact the degree to which I experience swelling? Is this swelling the reason I feel slight stinging even when I do not type, or is it residual heat?

Lastly, if it's not residual heat, could you also explain why without the hot plate as the stimulus, we feel pain? eg. not just with a hot plate, but when we accidentally whack our toe into a table leg, and quickly jump off, why does our toe throb even after the impact has ended like a couple of seconds before? -> has the pain been extended by our brain to make us remember, or is the signal continuously coming from our sensory neurones in our toe firing like crazy? -> I've done a quick reddit search and but only found the gympie gympie plant post about prolonged pain.

Sorry for the multiple questions, thank you very much! (re-post with question mark in title)

submitted by /u/silenceinanabyss
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Monozygotic twinning question?

Posted: 08 Sep 2019 10:56 AM PDT

Is the zygote before twinning one being that a piece of it comes off of to create the twin, or is it two beings in one that, splits apart? Or is it something else?

submitted by /u/fudwicker
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What field studies the interaction between wild species and humans throughout history?

Posted: 08 Sep 2019 11:47 AM PDT

I've been seeking a name for this subset of natural history for a while and thought I found it in Anthrozoology, but I'm not totally sure that best fits the specific topic I want to study.

I want to find similar stories of human interaction with wild species like that of the Australian Aboriginal tribes using Remoras to catch Green Sea Turtles.

Accounted here under "MODE OF CATCHING TURTLE":
https://www.gutenberg.org/files/12525/12525-h/12525-h.htm#chapter2.1

A live sucking-fish (Echeneis remora) having previously been secured by a line passed round the tail, is thrown into the water in certain places known to be suitable for the purpose; the fish while swimming about makes fast by its sucker to any turtle of this small kind which it may chance to encounter, and both are hauled in together!

Is there a more specific subset of zoology or anthropology that studies the ways humans have cohabited with wild animals or used them as a part of their culture?

Stories and accounts like using bears to locate honey hives, using ants to suture wounds, following baboons to water, tying string around a cormorants neck and having them catch fish, etc.

I especially prefer non-city interactions, though something like the battle between raccoons and human garbage infrastructure in the current day is also interesting.

What study is this? When reading through articles and papers on Anthrozoology I see only discussions of domesticated animals, humans handling species in conservation, and cultures trading in exotics.

Examples of those: https://www.depauw.edu/humanimalia/index.html

Do you know of the field I'm seeking, and what is the more specific term for it?

Thank you

submitted by /u/williamburwin
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what happens when a hurricane crosses hemispheres and has it happened before? how does it effect the hurricane?

Posted: 08 Sep 2019 11:57 AM PDT

I often read what an outside observer would see if I was falling into a black hole, but what would I see if I looked back out while falling into a black hole?

Posted: 08 Sep 2019 09:27 PM PDT

Even though I cant communicate back out, there should be no physical laws stopping me from looking back out of the black hole right?
Would time-dilation allow me to see the end of the universe?

Would everything get "blueshifted"?

submitted by /u/taracus
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Does the pH of soaps actually matter?

Posted: 08 Sep 2019 08:27 PM PDT

So much shampoo and soaps say pH balanced on the label. Also, I read that it isn't good to give cats dog shampoo because the pH isn't correct for them. I can't really seem to find much information on it because half of the Internet says it's a scam but the other half is adamant on how important it is. I'm unable to find genuinely useful information about it.

submitted by /u/weebcontrol240
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Are there warmer/colder regions of interstellar space? What causes these temperature differences and what are the warmer regions/colder regions called?

Posted: 08 Sep 2019 01:39 PM PDT

How do Led Lights/semi conductors function?

Posted: 08 Sep 2019 07:08 PM PDT

Hi, I 'm trying to learn how led/semiconductors work. What I understand so far is that there are 2 sides of the led. one contains negatively charged particles and the other positive. there are gaps in the atoms in the negative side, so the electrons from the positive side go to the other. By changing energy levels, energy has to be lost and it is lost by giving off light. depending on how much energy it is losing, the color changes. Is this correct?

Additionally, I was wondering how electrical discharge differs from leds. electrons flow from one side to the other side, and collide with gas particles which produces light. why does this method of lighting require gas, while leds only need the movement of electrons?

Thanks

submitted by /u/Cereal_Bird
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How does this "Mitochondrial Eve" thing work? Did humanity really population-bottleneck to a single female at one point in time?

Posted: 08 Sep 2019 05:21 PM PDT

So, every single living human being today, can have their lineage traced back to a Mitochondrial Eve. How does that even work? Did we really come that close to extinction that at some point, there was only one female human on the entire planet whose descendants didn't die out before making contact with others?

That's some cosmic horror level stuff right there. Every other pocket of human population dying, only the children of one woman living on... Holy crap...

Shouldn't this show some lower than normal genetic diversity tho? I heard cheetahs have debilitatingly low genetic dieversity due to a bottleneck in their population thousands of years ago... yet I never heard of humans having such.

submitted by /u/Doveen
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Are there any differences between a hurricane and a typhoon?

Posted: 08 Sep 2019 10:34 AM PDT

I was under the impression that they were the same storm, just on opposites sides of the world and spun different directions. Does this cause any different characteristics?

submitted by /u/Tuleycorn
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What absorbs more carbon - an acre of rainforest or an acre of soy/corn?

Posted: 08 Sep 2019 12:45 PM PDT

Had an argument with a guy from the agricultural sector. He claimed that the amazon fires aren't such a big deal for the climate crisis as most of the burned area is used to grow soy or corn later on, and that these crops absorb as much carbon as rainforest. I called b/s on that, but couldn't find any statistics when I googled it. Can anyone help? Is this guy wrong, and if so, why?

submitted by /u/Schanzenraute
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If two objects with different masses fall at the same rate in a vacuum, why does mass affect how the two objects act differently in Earth's atmosphere?

Posted: 08 Sep 2019 03:53 PM PDT

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