Ham radio operator here: basically neither will happen because both don't really mean anything.
This is an imperfect analogy, but I think it will set you thinking in the right direction: If someone is blinking a flashlight at you, and you're sitting right next to another person, do both of you see the flashlight at 100% brightness, or do your eyes wrestle for the same light waves?
What does "pick up the signal at 100%" mean? Let's say me and my buddy are talking on our car radios, no repeaters just point-to-point. If we start off in the same parking lot, we can easily hear each other. If we start driving in opposite directions, we'll still hear each other just fine, until one of two things happens: We go on either side of a hill or far enough to be beyond the horizon, and then abruptly stop hearing each other, or the signal will fade in intensity until the background noise is louder.
If we get to that point where the signal is weak but still receivable, increasing output power of the transmitter, or switching to a directional antenna might help. People tend to think antenna gain is some magic that makes the radio louder, but it's not. A high gain antenna does the same thing that cupping your hand behind your ear or around your mouth does; it puts more of the energy that would have gone in different directions in the direction you need.
Without getting too far into antenna theory, I will say that yes having two antennas near each other can cause them to interfere with each other. "Wrestle for the same radio waves" isn't the way I would describe it. Antennas resonate with radio waves, it's like a tuning fork, if you play the note the tuning fork is tuned to, the tuning fork will start to vibrate and emit its own sound. If two antennas are quite close together, this can cause destructive interference. You can use the same principle to construct a high gain antenna; look up how yagi antennas work for more details.
possibly several things but my first thought is your body is acting like a capacitor to ground. I'm guessing you've noticed this on an FM radio or rabbit ears on a TV that probably weren't grounded well.
In some cases you're tuning (or detuning) the antenna capacitively.
On other cases, like if your tv gets interference when you're standing in part the room, there may be standing waves causing interference, as the rf is bouncing around your room.
To further your point, theorically, there is a voltage potential between any two objects. That's the capacitance. Better conductor, for the same surface area, create a bigger potential.
So when you tune/detune a signal with your presence near the antenna, it is because you are close enough to the antenna that the potential between you and the antenna affects the filter of the signal.
How do you think you are changing the resonant frequency? By modifying it's capacitive impedence, i.e. creating a capacitor with yourself and the antenna.
And you know what we call the difference of electric potential between two points? Voltage.
When you say that capacitance is geometry, you are right. The distance between two objects, be it you and an antenna or two planks of wood, affect the capacitive impedance.
As the distance increase between two surfaces, the capacitance diminishes and the voltage between the two increase, so that C=QV is always true.
The resonant frequency is determined by the impedence, i.e. capacitive and inductive impedence.
You can't affect inductive impedance of the antenna because you are not a coil and do not emit EMR. But you can change the capacitance between you and the antenna by moving closer or further away.
as the distance increases the capacitance reduces. But C=Q/V doesn't mean you're not inducing any potential into the antenna... You're adding to the load... C=ε*A/d is the equation that says capacitance will decrease with distance, but that isn't going to induce any voltage in this case.
yes this is what I'm saying.
in the very near field, conductive tissue, ie a body, will have Eddy currents. Your body has an ε term as well as σ. You can definitely load an antenna. The R term will dominate but there will be some effect on inductance.
I don't know what chain reaction exactly they were thinking of, but from modern fusion research, I believe we can confidently say that the atmosphere would need to be interior-of-a-large-star-level dense, and even then I'm not sure you'd get nitrogen fusing with anything without a lot of hydrogen or helium around. Nitrogen-nitrogen fusion seems extremely implausible for sure
Prolly the most relevant paragraph from the linked article for this discussion:
Today, especially after the detonation of the 50 MT Tsar hydrogen bomb on Novaya Zemlya in 1961, it is also experimentally verified that the danger of atmospheric or even oceanic ignition does not exist. Also, the experimental measurements obtained by Zucker and others demonstrate that the fusion probability is much smaller than the geometric cross-section for 14N+14N assumed by Teller and coworkers, further reducing the chances for such an event. Furthermore, the atmosphere is also heated only to temperatures of a few million degrees, so that the most efficient energies of the fusing nuclei are a few 100 keV and thus well below the Coulomb barrier and very much reduced by penetrability. These temperatures are noticeably lower than those in the late hydrostatic burning stages of massive stars.
Basically the temperature of the atmosphere is over an order of magnitude too low to have any chance of ignition (need 10s of millions of K), and the reaction rate is thus several orders of magnitude lower than the threshold.
i think the idea is that the part that already fused creates a blast wave that could create the conditions, including preassure required for more fusion. i have no idea if it's possible though.
Yeah, you're not going to get a self-sustaining reaction in Earth's atmosphere if it wasn't already hot and compressed enough that there would be a self-sustaining reaction happening anyway. It's just not a plausible concern. You only get self-sustaining fusion in stars, so Earth would have to be a star in this scenario.
You and the person on a chair on the beach next to you will both get sunburnt. In the same way, radio waves washing around your house or car interacts with everything, antenna or not.
It would turn scary if the atmosphere would become as dense as the core of a star. Then too, a lot of stuff depends on the type of star we're talking about. Are we talking about some wimpy red dwarf core density? Yeah, we'll fuse the hydrogen in the atmosphere/on the surface all right. U wanna fuse nitrogen? Oof. U'r gonna need a much bigger star than that.
So basically, to become scary, ur atmosphere would have to be a lot more dense than what it would be if it was fkin solid (like if the gases were literally solid). It wouldn't thus be an atmosphere.
People are answering what you asked but what you probably mean is in a 2d world where two antenna are perfectly in line with the transmitter will the first absorb some of the signal - yes it will, just like two wind turbines in a line it's absorbing the energy from the medium and using it to do work.
It's not always so simple, it might spit some of if out too if it doesn't have anywhere else for it to go and it'll do this in a certain pattern which can, depending on the distance and arrangement ,increase the signal received by the second one. This and similar principles are why you see so many odd shapes for antenna designs such as the many bars on a TV antenna which make it more directional.
Depends. If the antennas were resonant dipoles placed some fraction of a wavelength away from each other (1/4 wave away), you may get some cancellation of the signal.
Look up the "yagi uda" antenna, it's the classic rooftop tv antenna. The elements are spaced by fractions of a wavelength to achieve directivity. One single element is driven, the others are just resonant lengths of wire.
The potential energy of the spring is “stored” in individual molecules that are pushed into some configuration that they don’t quite want to be in, and they exert force on each other trying to push themselves back apart / back together into being the way they like. As the spring disintegrates, you could model those individual forces, and molecules exerting force on each other would release it into kinetic energy one by one or in groups, as the spring gradually lost its integrity to exist as a singular entity.
(I think that in practice, metals are made of grains, big groupings of molecules which stay pretty much as rigid bodies unless something really crazy happens, so most of the potential energy is force of the grains wanting to go back into their preferred arrangement in relation to other grains. I.e. not in practice at the level of molecule to molecule. But I’m not 100% on that part.)
I would imagine that as the tiny bits of the spring are released from one another, the stored energy would be released as a small force within the acid. That is, even if the reaction was perfect down to the molecular level, the new molecule combination would be "launched" away from the spring more vigorously than if the spring weren't compressed. So you'd end up with the acid being "stirred" a bit by the reaction.
Assuming the spring dissolves perfectly (no breakage, just complete disintegration)
I think, eventually, this assumption breaks down. As the metal is dissolved away, the internal stresses in the spring will become greater than the remaining metal can hold, and the spring will break.
If the spring does eventually break, it will be a weaker spring since a lot of material is gone. The potential energy of a spring at the breaking point would be different than the original spring. So I guess I could rephrase the question, what happens until that point? Does it get let go as heat?
Fair enough, thinking about it at a microscopic level, individual molecules/atoms of material will be pushed into positions where they are being repelled from other atoms/molecules via electromagnetic forces. Those forces won't go away as the chemical reactions happen; so, I would guess that the answer is kinda the same as it is at the macroscopic level. When the bond which holds an individual atom in the lattice of the material is broken, those electromagnetic forces would push the resulting molecule away. So ya, it becomes heat.
That's one hell of an assumption. It's not gonna break down equally across the entire spring. Whatever the weakest point is will eventually wear away first and cause it to break because of all the tension in it.
Even if it could dissolve equally across the entire spring, the outer parts would go first and it eventually will dissolve away from the things holding it in place and release that tension. If it doesn't just break due to the dissolving metal weakening the structure while still under tension.
I feel like to get the meat and potatoes of the question a better way of asking would be what would happen to the potential energy if the spring was instantly vaporized, like by a Star Trek phaser.
The greenhouse gas "problem" is necessary to survive. If the greenhouse effect didn't exist, neither would life as we know it.
The issue with combusting non-renewables is that that energy used to be sequestered away from the carbon cycle, effectively allowing for a balance without too much overall disruption (certain natural events notwithstanding).
So now, with all this stored away, not-part-of-the-carbon-cycle carbon being burned up, we're adding more to the carbon cycle, disrupting it, and causing a new higher thermal equilibrium (which has yet to be reached due to geological time scales). Side note: water is a better greenhouse gas than methane or carbon, but it's accounted for.
Because the greenhouse effect still exists, and we're adding more greenhouse gasses, the greenhouse effect will not allow heat to transfer to space as easily.
With solar being "captured" by a black roof, that would be mostly negligible, as a portion of that energy will potentially radiate away during the capture process. However, with more greenhouse gasses being dumped into the atmosphere, that radiative cooling will become less viable as time goes on, as it too will stay largely captured.
We need to reduce greenhouse gas emissions, otherwise it'll cause a runaway effect. That part might be too late.
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