144 replies to this topic

[D.K.]

Holy mother... I'd like to join in the discussion, but I'm afraid that mine knowledge of english is far too inferior to yours, to be precise, I don't know much of those scientific expressions, as no one here learns you...

Though, I'd like to put a question for Dauth:

What causes some elements to dissolve or react faster when in colder conditions. I suppose that it has some connection with inter-molecular hydrogen connections (don't know the correct english explanation for it, it's a link between atoms of water, if you know what I'm talking about)?

[Dauth]

Faster in colder conditions, I think you may be on about something like the Born-Haber synthesis of Ammonia. The thing is all reactions can eb reversed (depending on the conditions), Ammonia dissolves into nitrogen and hydrogen as temperature increases, conversely in lower temperatures the elements for Ammonia.

Reactions tend to be faster at higher temperatures since there are more interactions per second, and more molecules have enough energy to overcome the activation energy. As for faster when colder I'd like to see a specific example to help describe it.

Hope this helps.

[Z_mann]

Hokay, I've been thinking about this for a while, and I'm not sure how this works.

When a capacitor is in the process of charging, labor(work?) is done by an external source - a battery of sorts, for example. When said force is terminated, charge separation persists and a certain amount of energy is stored, until the system is returned into equilibrium (joining the poles).

My question is: where is the energy actually being stored? Especially if the capacitor is divided by vacuum.

[BeefJeRKy]

Z_mann, on 31 Jan 2009, 19:08, said:

Hokay, I've been thinking about this for a while, and I'm not sure how this works.

When a capacitor is in the process of charging, labor(work?) is done by an external source - a battery of sorts, for example. When said force is terminated, charge separation persists and a certain amount of energy is stored, until the system is returned into equilibrium (joining the poles).

My question is: where is the energy actually being stored? Especially if the capacitor is divided by vacuum.

Energy is stored as electric potential energy in the Uniform Electric Field I believe. Energy doesn't require a material to be stored in. In fact, many capacitors use dielectric materials for higher capacitance and better structure I think. We'll have Dauth confirm this.

[Dr. Strangelove]

Are there any particle beams that are fired into the atmosphere fast enough to generate Cerenkov radiation in mid-air?

Z_mann, on 1 Feb 2009, 1:08, said:

Hokay, I've been thinking about this for a while, and I'm not sure how this works.

When a capacitor is in the process of charging, labor(work?) is done by an external source - a battery of sorts, for example. When said force is terminated, charge separation persists and a certain amount of energy is stored, until the system is returned into equilibrium (joining the poles).

My question is: where is the energy actually being stored? Especially if the capacitor is divided by vacuum.

It's stored in the electrostatic fields that hold the electrons on the negatively charged side.

[Dauth]

The gamma factor to go faster than light in air is 43.58, if you shunted some of the big particle detectors straight up that would work but the beam would decompose very quickly in a free atmosphere. Any OMG particles moving in should be able to cause it, but you're looking at single photons and not something visible to the human eye.

[Dr. Strangelove]

Given a device which radiates a neutron flux of 1.1 Billion neutrons a second in all directions, is it possible to use that device to breed P-239 out of Tobernite? What if you have one that produces 15.5 Giga-Neutrons/s and you are breeding pitchblende? If the neutrons have 14.1 and 2.45 MeV, is a moderator necessary?

[Dauth]

Dude thats a little deeper than I'd generally like to go.

Phosphorous-239 (P-239) has never and I suspect will never be observed.

if you're after Plutonium, then I think that you should talk to real nuclear physicists. i would always recommend a moderator, just so you can control the reaction and prevent it going super critical.

[Dr. Strangelove]

Dauth, on 15 Mar 2010, 10:09, said:

Dude thats a little deeper than I'd generally like to go.

Phosphorous-239 (P-239) has never and I suspect will never be observed.

if you're after Plutonium, then I think that you should talk to real nuclear physicists. i would always recommend a moderator, just so you can control the reaction and prevent it going super critical.

Well, it's just that, purely speculating here, if given those conditions you CAN productively breed plutonium, I might have found a way someone could assemble a nuclear bomb. Not that I would ever approach that Darwin Award level stupidity.

[Chyros]

The Machman, on 15 Mar 2010, 11:26, said:

Dauth, on 15 Mar 2010, 10:09, said:

Dude thats a little deeper than I'd generally like to go.

Phosphorous-239 (P-239) has never and I suspect will never be observed.

if you're after Plutonium, then I think that you should talk to real nuclear physicists. i would always recommend a moderator, just so you can control the reaction and prevent it going super critical.

Well, it's just that, purely speculating here, if given those conditions you CAN productively breed plutonium, I might have found a way someone could assemble a nuclear bomb. Not that I would ever approach that Darwin Award level stupidity.

Of course he means Pu-239, not P-239 .

Just from nuclear collision you'd probably not manage to make critical mass anyway, since you need about 10 kg = 41 moles = 2,5∙10²⁵ atoms of Pu-239. Considering the chances of one nuclear collision happening I'd say that's not bloody likely .

[Dr. Strangelove]

Let's say you have two dynodes in a vacuum tube, and you apply a RF signal to them so that they are 90 degrees out of phase, and then make this signal resonant with the electron flight time across the tube at whatever voltage the dynodes are charged to(let's say 20kV for the sake of debate). When the electrons slam into the dynode, they should release more electrons via secondary electron emission. Now this might seem like one of those really, really, really, "Well DUH" kind of questions, but when the secondary electrons are created does that cause the plate they are liberated from to have a higher positive potential due to lost electrons?

Edited by Dr. Strangelove, 14 May 2010 - 03:20.

[Golan]

You mean creating an infinite photo-multiplier?

Emitting electrons will naturally make the dynode charged more positively compared to its state before the emission simply due to the decrease in electron number.

[quantumhead]

Gamma waves have the smallest wavelength on the electromagnetic spectrum (of the order of 10^-12), and radio waves have the greatest wavelength (of the order of 10^4). How can you explain the fact that they both travel through matter whereas visible light, which has a wavelength between the two others, cannot travel through matter? Also, why does visible light go through glass but not other solid materials?

[Destiny]

Uhh...not all materials are transparent you know...

[Sgt. Rho]

radio and gamma waves both don't go through solid matter if you have enough of it

Edited by Sargeant Rho, 20 September 2010 - 16:22.

[Golan]

Okay, first off, visible EM-waves can travel through many types of matter and non-visible EM-waves can also not travel through many types of matter. If you ever tried using a cellphone in an elevator or have been wearing glasses, you have experienced this.

As you might have heard, electromagnetic waves exist only in discrete packages, so called photons. Every photon carries a discrete amount of energy defined by its frequency, E=hv. This means that electromagnetic waves of different frequency (and as such, wavelength) also have a proportionally different energy (inversely proportional to the wavelength). For example, gamma radiation has the highest energy per photon whereas radio waves carry only little energy per photon.
Now, the transparency/opacity of an object depends on what amounts of energy it can absorb. For example, electrons orbiting around an atom nucleus carry discrete amounts of energy based on their orbiting radius (similar to the photon's energy-frequency relation) while the radii themselves are also limited to discrete values - thus, an electron absorbing photons to "hop" onto a wider radius can only absorb photons of a specific, limited frequency range. This usually happens in the range of and around of the visible spectrum. It is also the reason why the transparency of a material can be used as a rough indicator for how well it serves as an electrical insulator (e.g. transparent materials have their electrons bound tightly).
Other frequencies are subject to absorption through other effects - for example, photons can be absorbed by atom nuclei directly or link into the natural Brownian oscillation of crystals. Also, many materials will have the individual effects work together - for example, a photon can loose energy by physically hitting a nucleus, then be absorbed by an electron due to its energy now matching the gap energy, then re-emitted by the electron jumping back to its initial radius and then absorbed by another material.

Edited by Golan, 20 September 2010 - 16:27.

[BeefJeRKy]

I believe that materials arranged in crystalline lattices would also exhibit different optical properties too right?

[Dauth]

scope, on 20 Sep 2010, 18:08, said:

I believe that materials arranged in crystalline lattices would also exhibit different optical properties too right?

Correct, just look at Graphite and Diamond for an example.


Spectra for the atmosphere

[Alice Brown]

Good stuff! Learn a lot from the reading! Don't know if you still take questions, but I have one broad, hard question for you, which is more biology-related I think: what is exactly the cause of cancer? It's said that genes can also be one of the factors resulting in cancer? Is it correct?

Wish I could get your answer!

[CJ]

I'm afraid Dauth has left the forums and hasn't really been on for years now :|