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What Happens to the Extra Volt in a 6-Volt Lamp?
If we're talking old school incandescent bulbs, the light output and heat vary with voltage. And so does bulb life. For many bulbs, the manufacturer provides specs for the same bulb run at different voltages. A bulb might be a bit dim but last nearly forever at 5.5V, bright and last a usefully longRead more
If we’re talking old school incandescent bulbs, the light output and heat vary with voltage. And so does bulb life. For many bulbs, the manufacturer provides specs for the same bulb run at different voltages. A bulb might be a bit dim but last nearly forever at 5.5V, bright and last a usefully long time at 6V, super bright but short lived at 7V.
Colour temperature also changes, as you would expect from different temperatures. Light will have a warmer colour at lower voltage and temperature, closer to white at higher voltage and temperature.
See lessWhy Are So Few Rocks As Old As Our Solar System’s Origins?
The earth is an active system. We have tectonic plates that move and essentially recycle the rocks over time. There's also erosion, pressure, heat and other things that destroy the stone or change it so the history is lost. Some rocks like sandstone are hard to date. It's very hard to find rocks soRead more
The earth is an active system. We have tectonic plates that move and essentially recycle the rocks over time. There’s also erosion, pressure, heat and other things that destroy the stone or change it so the history is lost. Some rocks like sandstone are hard to date.
It’s very hard to find rocks so old because of these problems.
The book Story of Earth by Hazen is a very good book on this matter and explains also how we arrived at that number.
See lessCan We Harness Degeneracy Pressure to Alter Matter States?
If you have a material that is compressed a lot and then suddenly release the pressure then it will explode, yes. A diamond anvil cell can reach such a pressure. I'm not sure about the fast release mechanism, but that's probably possible to arrange.
If you have a material that is compressed a lot and then suddenly release the pressure then it will explode, yes. A diamond anvil cell can reach such a pressure. I’m not sure about the fast release mechanism, but that’s probably possible to arrange.
See lessWhat Do Electron Orbital Shapes Reveal About Atomic Structure?
The angular behavior of the hydrogenic electron orbitals are described by the [spherical harmonics](https://en.wikipedia.org/wiki/Spherical _harmonics). The cylindrical symmetry that you have noticed comes about because the states are described and organized in terms of their angular momentum alongRead more
The angular behavior of the hydrogenic electron orbitals are described by the [spherical harmonics](https://en.wikipedia.org/wiki/Spherical _harmonics). The cylindrical symmetry that you have noticed comes about because the states are described and organized in terms of their angular momentum along the z-axis. If there is a preferred direction (because we are for example studying an atom in an electromagnetic field) we tend to use this representation of the states and choose the z-axis such that its direction aligns with the preferred direction. This often makes studying the problem easier since a physical fact about the system is embedded in the math itself.
If there is no such preferred direction it is often convenient to use the so called [real spherical harmonics](https://en.wikipedia.org/wiki/Spherical_harmonics#Real_form) instead. These are just combinations of the previous ones that end up having the same mathematical properties with the exception of there not really being such a preferred direction. You can visualize the hydrogenic orbitals in this representation instead if you want: https://en.wikipedia.org/wiki/Table_of_spherical_harmonics#Visualization_of_real_spherical_harmonics
See lessWhat Happens to a Ball Thrown Upward in a Spinning Space Station?
Try and picture a view from outside the space station. The moment you let go of the ball, it travels in a straight line at constant speed, but that straight line is not towards the centre of the ring unless you threw the ball at an angle backwards exactly sufficient to cancel out your rotational speRead more
Try and picture a view from outside the space station. The moment you let go of the ball, it travels in a straight line at constant speed, but that straight line is not towards the centre of the ring unless you threw the ball at an angle backwards exactly sufficient to cancel out your rotational speed. This means that in general it will travel at some tangent to the circle.
In terms of how this will look for you, the anser is: weird. For quite a range of angles you throw it, there is I think a speed where it will hit the ground at the same place you have rotated to during its flight time, so it will appear to do some magic boomerang type movement. For other speeds and angles, it will do weird magic boomerang stuff and land somewhere ahead of or behind you. The bigger your space station rotating ring, the less magic boomerang stuff it will do, and the more it will feel like throwing a ball on earth.
See lessIs a Smaller Star Possible in a Solar System with a Giant Star?
Yes, systems with multiple stars are very common. Normally the stars are similar in mass but this is not an ironclad rule. The nearest star system to us is such a multiple system, with two stars of similar mass and a smaller red dwarf star orbiting those two. We also know of planets around several sRead more
Yes, systems with multiple stars are very common. Normally the stars are similar in mass but this is not an ironclad rule. The nearest star system to us is such a multiple system, with two stars of similar mass and a smaller red dwarf star orbiting those two. We also know of planets around several stars in binary system.
See lessHow Do Jet Engines and Rockets Enhance Thrust with Exhaust Design?
The nozzle of a rocket is actually doing more than you might expect! It's actually a form of [De Laval Nozzle](https://en.wikipedia.org/wiki/De_Laval_nozzle). For the first part of the nozzle, the flow does what you've intuited: it speeds up the exhaust because the cross sectional area gets reduced.Read more
The nozzle of a rocket is actually doing more than you might expect!
It’s actually a form of [De Laval Nozzle](https://en.wikipedia.org/wiki/De_Laval_nozzle). For the first part of the nozzle, the flow does what you’ve intuited: it speeds up the exhaust because the cross sectional area gets reduced.
But then the flow transitions to sonic / Mach 1 at the smallest part of the nozzle, and gets choked – it becomes very hard to get it to flow faster because the Mach 1 zone is basically limiting how fast you can get the flow to go. You can increase the chamber pressure, but the flow still piles up at the Mach 1 point even as you squeeze it harder.
But supersonic flow does something interesting: when the cross sectional area increases, the speed of the exhaust actually increases again! This part is a little counterintuitive because we’re more used to subsonic flow in our everyday experiences. So you can “squeeze down” the exaust to get it to move at the Mach 1 sonic transition point, and then to get it to move faster, you expand it back out again, and this is how you can get the exhaust to flow at supersonic velocities out of the engine bell.
So the short answer is that the nozzle shape is greatly, if not primarily, there to get the exhaust as fast as possible, because in general the harder you throw the exhaust out the back, the more reaction force you get for the same amount of mass, and the more efficient the rocket.
See lessDid the decline of bugs on windshields impact insect populations?
The amount of insects that die on the windshield is negligible, the loss of habitat is the main issue mainly because we converted a lot of the land into farms destroying a considerable amount of the habitat and also the use of pesticides that usually affect even beyond the farms where they are appliRead more
The amount of insects that die on the windshield is negligible, the loss of habitat is the main issue mainly because we converted a lot of the land into farms destroying a considerable amount of the habitat and also the use of pesticides that usually affect even beyond the farms where they are applied
See lessWhat Forces Drive Entropy Increase in Osmosis and Molecule Movement?
We tend to more often see scenarios that are more likely to occur. Entropy quantifies the number of ways a scenario can occur (e.g., the position and speed of microscale particles consistent with a macroscale temperature or pressure or chemical potential, say, that we measure). Replace “tend to moreRead more
We tend to more often see scenarios that are more likely to occur.
Entropy quantifies the number of ways a scenario can occur (e.g., the position and speed of microscale particles consistent with a macroscale temperature or pressure or chemical potential, say, that we measure).
Replace “tend to more often” with “always” when considering the vast number of particles participating in osmosis, for instance.
So we always see total entropy being maximized—not from a fundamental force but based on a statistical tendency that we can absolutely rely on, given the circumstances. This total entropy maximization corresponds to the Gibbs free energy being minimized locally when a system can thermally and mechanically interact with its surroundings, as I review [here](https://physics.stackexchange.com/a/386789/146039). So osmosis proceeds, as do most processes around us, in order to minimize the Gibbs free energy.
Another way to look at is that molecules, existing as they do in a thermal bath that gives them constant momentum kicks, will do anything and go anywhere they can. In the case of osmosis, the molecules that can’t pass through the membrane bounce off it, entraining and effectively pumping the molecules from the other side that can pass through.
Does this clarify things?
See lessIs There a Cure for Dengue Like for Hepatitis and Chickenpox?
The fundamental difficulty of making effective antivirals is very similar to the difficulty of making anticancer drugs without horrendous side effects - most of the machinery involved in viral replication is that of your own cells, so finding orthogonal, druggable targets is very challenging. If youRead more
The fundamental difficulty of making effective antivirals is very similar to the difficulty of making anticancer drugs without horrendous side effects – most of the machinery involved in viral replication is that of your own cells, so finding orthogonal, druggable targets is very challenging.
If you look at the linked Nature paper above the proposes pimecrilomus (an approved immune suppressant for conditions like eczema) they don’t actually know how or why it inhibits Dengue viral replication. Sometimes we stumble upon those kinds of drugs, but more often we need a specific viral protein to target (e.g. reverse transcriptases, integrases, or viral proteases). Sometimes we can find a clear target to work with, but in other situations that just proves to be very difficult.
See lessCan the World Supply Enough Lithium for EVs and Solar Demand?
Lithium ion batteries are not the only way to store electricity, they are just popular for leigthweight consumer electronics right now. So to store massive amoints of power for night time usage we wont be using lithium but pump water up a dam or similar. In theory the planet has enough lithium to poRead more
Lithium ion batteries are not the only way to store electricity, they are just popular for leigthweight consumer electronics right now.
So to store massive amoints of power for night time usage we wont be using lithium but pump water up a dam or similar.
In theory the planet has enough lithium to power all the phones and probably cars too, it would just get more and mlre expensive to extract and with that the price would go up.
So its probably worth at some point to take any other battery type and ise that for the car even if that means its going to weight more.
See lessCan We Ever Observe Particles Smaller Than Quarks’ Limits?
there actually is an lower limit. you see - the smaller the object is, that you want to detect, the more energy you must cram into a small volume to achieve the necessary resolution. at some point, you cram so much energy in a so small volume of space, that you basically create a black hole. and thiRead more
there actually is an lower limit.
you see – the smaller the object is, that you want to detect, the more energy you must cram into a small volume to achieve the necessary resolution. at some point, you cram so much energy in a so small volume of space, that you basically create a black hole. and this is the smallest “object” you could theoretically detect. for smaller objects you would need more energy, thus making the black hole bigger, not smaller.
because of the way, the planck scale is definied, this limit is the planck length. you would have to cram one unit of planck-energy into one unit of planck volume – which is the tiniest black hole possible.
some folks assume, that because of this the planck scale is the absolute lower limit for anything – that space is kind “pixelated”. but this assumption is not necessaryly correct. we have no way to detect, if space itself is somehow “quantized”. so this assumption is not scientific.
ok – off topic: a “particle” is a quantum object. it has no definied size. when a scientist talks about the size of a particle, they usually mean the cross section of the particle – the volume of space, where an interaction of this particle with something else is almost guaranteed. the interaction itself can be point-like – aka, has size zero. but the particle has no definied size at all.
See lessCan High-Velocity Objects Create Black Holes Beyond Limits?
This question comes from a common, but fundamental, misunderstanding of relativity. When someone asks it, I like to answer their question with another: There is a perfectly legit reference frame in which you are currently traveling at 99.99999999999999999999% of the speed of light. Have you collapseRead more
This question comes from a common, but fundamental, misunderstanding of relativity. When someone asks it, I like to answer their question with another: There is a perfectly legit reference frame in which you are currently traveling at 99.99999999999999999999% of the speed of light. Have you collapsed into a black hole?
Since all inertial reference frames are equally valid according to relativity (aka, there are no [preferred frames](https://en.wikipedia.org/wiki/Preferred_frame)), we can say you are traveling at any speed less than ‘c’ that we want. And not only say it, but it’s true. So, this should help people understand other common misconceptions- for instance there is no frame where your clock ticks slowest (due to time dilation), all clocks ticks at “one second per second.”
To answer why fast moving objects don’t collapse into black holes- the concept of “relativistic mass” was a sloppy one, which some physicists like to use but has really fallen out of favor because it causes a lot of confusion, like this question. In Special Relativity you’ll see this same factor, 1/sqrt(1-v^(2)/c^(2)) show up a lot, and we call it “gamma.” For instance, dt’ = gamma*dt (which is the famous time dilation equation, where if you’re moving fast relative to me, I’ll see your clock running slower). Well, the “standard” momentum equation in physics is p = mv (momentum equals mass times velocity) and in special relativity, that becomes p = mv/gamma. So, what some physicists did was say “oh, we’ll say p = (m/gamma)*v and then call (m/gamma) “relativistic mass” which implies as velocity goes up, mass goes up. And for *some* limited calculations, that intuition works, but for a lot of others, it doesn’t. However, the physics only applies to the momentum- if you are moving fast relative to me, I will measure your momentum to be based on that equation- the physics doesn’t say it’s mass going up, it talks about momentum. That’s real.
See lessDo magnets weaken in storage? Tips to preserve their strength!
Magnets tend to lose about 1% of their field strength over the span of 100years. That is if properly cared for : no impacts, exposure to electrical currents (i.e. no wires with live current near or on them), no heat. Store them pole to reverse pole (N to S to N to S etc) and you should be ok for yeaRead more
Magnets tend to lose about 1% of their field strength over the span of 100years. That is if properly cared for : no impacts, exposure to electrical currents (i.e. no wires with live current near or on them), no heat.
Store them pole to reverse pole (N to S to N to S etc) and you should be ok for years.
See lessWhat unique bacteria thrive exclusively in oil environments?
Probably not the exact answer you're looking for but there are plenty of anaerobic bacteria that live in microscopic droplets emulsified in oil. C. botulinum is a great example and why garlic in oil is a big no no without some preservation technique. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1105Read more
Probably not the exact answer you’re looking for but there are plenty of anaerobic bacteria that live in microscopic droplets emulsified in oil. C. botulinum is a great example and why garlic in oil is a big no no without some preservation technique.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11057212/
See lessCan a Blobfish Survive Slow Ascent Without Becoming Blobby?
It will blobbify. No matter how slowly you go you cannot stop the human body from dying at extreme pressure as you go lower. Similarly you can't stop a blobfish from dying by going slowly. Something you should remember is that humans need a careful process to return to their ORIGINAL pressure. A bloRead more
It will blobbify.
No matter how slowly you go you cannot stop the human body from dying at extreme pressure as you go lower.
Similarly you can’t stop a blobfish from dying by going slowly.
Something you should remember is that humans need a careful process to return to their ORIGINAL pressure. A blobfish has no chance when being raised up to a completely new pressure.
See less