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An Ikea Bowl Has Been Setting Things on Fire

atlasobscura.com

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Re: An Ikea Bowl Has Been Setting Things on Fire

#81

Post by pavel_lishin »

buserror wrote: post #18
Freak_NL wrote: post #12

The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their…

Actually one of the official 'old school' tool to measure sun exposure thru the day in meteo stations is a glass sphere with a calibrated piece of paper underneath. Needs to be changed everyday, but the burn mark is quite neatly drawn on the chart. EDIT: Found it again https://en.wikipedia.org/wiki/Campbell%E2%80%93Stokes_record...

I've never seen a glass sphere this large - it's almost surreal: https://en.wikipedia.org/wiki/Campbell%E2%80%93Stokes_record...

I keep looking at it, my brain confused why I can't see through what is clearly a transparent object. It doesn't feel like I'm looking through it, though inverted; it feels like I'm seeing a weird depiction of the nature scene around me plastered on its surface.

Re: An Ikea Bowl Has Been Setting Things on Fire

#83

Post by sqeaky »

djmips wrote: post #77
camiller wrote: post #55

Earlier quoted context omitted.

I believe that mythbusters had an episode disproving the Archimedes heat ray

Yeah, like Mythbusters is definitive science. I'll half ass this with my high school level of education and TV budget and deadline and fail and declare it definitively busted!

No science is definitive. Even Isaac Newton was overturned.

As near as I can tell they have put the most effort into duplicating Archimedes Heat Ray. They attempted it three times with large budgets and demonstrated why it was possible, but entirely impractical.

After they showed that just being wet was enough to save the boat (when would a boat ever be wet?!) they then offered a replacement explanation and had an example of a flaming arrow. It took one archer and required a fraction of the cost, could be reliably duplicated thousands of times (in battle) and had better range than a team of guys with mirrors.

Re: An Ikea Bowl Has Been Setting Things on Fire

#84

Post by ptaipale »

burkaman wrote: post #79
elliottcarlson wrote: post #65

Earlier quoted context omitted.

Where is the line between clickbait and attention grabbing headline. In the case of "You won't believe THIS simple trick to..." I'd definitely call it clickbait - but in this instance, the title reflects exactly what the article is about, and while the modified title on HN does a far better representation of the contents, I personally don't see the harm in how Atlas Obscura worded the title. Or maybe I am just really…

This is a very minor example, but compare the title to just "Ikea Bowl Has Been Setting Things on Fire". The word "this" naturally prompts the response "which one?", just like something saying "look at this" in real life. Again it's very minor, but the extra word adds nothing except a slight suggestion that this particular example is especially interesting and you should click to see it. Compare "Florida Man Escapes…

Yes, except that "This" in a title is a definite turn-off for me, and a sure way to make me avoid clicking. So sick of baiting.

Re: An Ikea Bowl Has Been Setting Things on Fire

#85

Post by cowpewter »

Freak_NL wrote: post #12

The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their…

It's really common with round fishbowls as well.

https://www.youtube.com/watch?v=QV-Y74YH51M

Re: An Ikea Bowl Has Been Setting Things on Fire

#86

Post by amelius »

koolba wrote: post #50
amelius wrote: post #33

Earlier quoted context omitted.

But actually how close is the bowl to a parabola?

I'm going to find out this afternoon. I've got two of these at home (the medium sized and the large one). I'm guessing the overall shape is the same between those and the small size one pictured in the article. We'll see!

I hope your house is still there when you get home ;)

Re: An Ikea Bowl Has Been Setting Things on Fire

#88

Post by datenwolf »

alfonsodev wrote: post #6

could be this adapted receive better wifi signal ?

Of course. As a matter of fact I once bought that very exact bowl for making a S band dish antenna.

There's a small caveat: The bottom of the bowl is flattened (so that it doesn't roll around). That's not a big deal though if you use a dipole feed; since the dipol radiates mostly normal to its axis (look up the pattern if it's unclear what I mean) a dipole mounted at the center and perpendicular to that flatted base will actually not "see" much of that flat base and work only against the curved part.

Due to the rather small radius and being a spherical shape the directivity/gain is not that great, compared to a parabolic dish antenna. But it's cheap and works well enough if you have to cover only a couple of km.

However keep in mind that regulations likely limit maximum transmission power to something like 20dB(m) EIRP, so depending on how much directivity gain you get, you'll have to reduce the TX power by that amount to stay legal… or get a license.

Re: An Ikea Bowl Has Been Setting Things on Fire

#89

Post by eric_h »

Freak_NL wrote: post #12

The same phenomenon occurs with glass spheres. If you think about it it is obvious enough (most people are familiar with how a magnifying glass concentrates the ray of the sun in a single spot), but it is something people tend to overlook when employing glass spheres as elements of your interior design — e.g., glass door knobs, large marbles, and decorative knick-knacks (which people have a tendency to place on their…

Indeed, some friends of mine in college had an acrylic sphere that they left on a couch while they went to class. They came back to find the FDNY finishing up putting out the fire it caused.

Re: An Ikea Bowl Has Been Setting Things on Fire

#90

Post by ythn »

dekhn wrote: post #74
ythn wrote: post #68

Earlier quoted context omitted.

I think it would actually be quite difficult to start a fire with this. Speaking as a former boy scout who had to build a fire with a magnifying glass for wilderness survival merit badge - it's really easy get smoke, it's quite difficult to get a flame. The article claims that he "set a piece of newspaper on fire" using the bowl, but after watching the video I just saw some smoldering paper - no flames. I'm betting t…

I can set a piece of cardboard on fire with visible flames in a few seconds. I carry a small fresnel lens, https://www.amazon.com/3-Pack-Credit-Card-Pocket-Fresnel/dp/...

I still maintain that it is much more difficult to start a fire with a lens or mirror than people seem to think. Post a video of using your fresnel lens on different material types (paper, cardboard, wood, pine needles) and see how quickly you can get a visible flame. I'm betting you won't be able to easily get a visible flame on most materials you try.
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