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I don't know about a graph (it would be awfully big!), but you can find TABLES of most elemental spectra. For example, look in any handbook of chemistry and physics. You'll see about 100 pages just to list most of the spectra of the elements.

Dr. Louis Barbier

From your question it's not clear whether you are referring to electromagnetic radiation (the energy spectrum, including ultraviolet, X-ray, gamma-ray radiation, etc.) or "nuclear radiation."

You can learn a lot about electromagnetic radiation on the "Imagine the Universe!" site with their Electromagnetic Spectrum Introduction.

And the EPA has a good description of nuclear radiation at their page: What is Radiation?

Dr. Louis Barbier and Beth Barbier
(June 2003)

I'm no expert on radiocarbon dating. The parent nuclei is mostly atmospheric nitrogen, and since most of the nitrogen in the atmosphere is N2, I would expect cyanide to be produced. But I don't know how long the cyanide would survive, or if it even survives the nuclear collision that forms the C14. The chemical binding energy is much less than the energy of the collision.

I found a web site that has a tutorial on C14.

If it doesn't have your answer, perhaps one of the scientists who set up the site can help you more.

Dr. Eric Christian

If you expose silica to enough radiation, yes, it will become radioactive. However the cosmic radiation that we measure is a low enough rate (about 1 particle per square foot per second) that our detectors have negligible residual radioactivity.

Dr. Eric Christian

Your reasoning is correct -- any acceleration of a charged particle results in radiation and consequent loss of energy. This holds true in a magnetic field, as well, and the resulting radiation is called "synchrotron radiation" or "cyclotron radiation", depending on the particle energy. These names came from particle accelerators, where the radiation was seen. Synchrotron radiation also is observed, by radio telescopes, coming from energetic electrons gyrating in astrophysical magnetic fields.

The loss of energy does result in the particle trajectory in the magnetic field deviating some from the uniform circular motion. The force that does this is called "radiation reaction" -- the momentum in the emitted radiation causes an equal and opposite momentum change of the particle, which slows the charged particle down. This force is usually very small, but given long enough, the charged particle will, in principle, lose all of its kinetic energy. At low enough particle energies, quantum mechanics becomes relevant, and this classical picture breaks down.

Cyclotron and synchrotron radiation are discussed correctly in several web sites (try Wikipedia), but I was unable to find a clear discussion of the associated energy loss of the charged particles.

Dr. Randy Jokipii
(May 2005)

There's a good Web site at the Princeton Plasma Physics Laboratory.

Dr. Louis Barbier and Beth Barbier

I'm sorry to say that there is no credible evidence that cold (room temperature) fusion takes place. There was a big stir a few years back when two University of Utah experimenters (Fleischman and Pons) announced at a press conference that they had discovered cold fusion. If so, it would have definitely changed the world. Subsequent work showed that there was no such thing under the conditions they had claimed.

It has been explained as everything from an honest mistake to downright fraud. A few fringe scientists still try and attract investors because they claim something was there, but responsible scientists have written it off.

Dr. Eric Christian

We think you are confusing the symmetry of the electron's orbit with the stability of the atom. Electrons aren't actually on perfect orbits, nor are they expected to be, as dictated by Quantum Mechanics. We can discuss the "average" radius of the orbit, but we cannot know it exactly.

The description of electron "orbits" is somewhat historical. The stability of an atom depends largely on the number of electrons in orbit around the nucleus and, of course, on the number of protons and neutrons in the nucleus. Stable elements have reached a minimum energy configuration, i.e. it would take more energy to change the configuration of the atom (and so the atom doesn't change!)

You can read more about atomic structure at Terrific Scientific.

Dr. Georgia de Nolfo
(October 2004)

As far as I am aware, the question of attraction or repulsion of unlike and like electrical charges is regarded as laws resulting from observation. That is, the effect is a basic law of nature, much in the same way that gravitational attraction of masses is.

The attraction or repulsion may be taken to be a manifestation of a force field that permeates space, such as the electric field (due to a charge) or gravitational field (due to a mass). These force fields can be taken to be mediated by virtual particles. But I don't believe that they are the consequence of any derivation from a more fundamental theory.

In this case the answer as to "why" is just not known.

Dr. Randy Jokipii
(December 2004)

No, they don't. I regret that it gets a little more complicated than that. First, let's remember that magnetic fields are associated with currents, which are moving charges. Magnets have small currents in them formed by the alignment of the electron currents as they orbit the atoms.

Some things are the same. Two positive charges repel each other. So do the positive poles of two magnets. However, the force between them is not the same.

There is one big difference between electric charge and the poles of a magnet: charge can exist as a single entity by itself - just one charge and no other. Magnetic poles must exist in pairs and for every "+" pole there is a "-" pole. This is where it gets complicated. When you ask what is the magnetic field of the "+" pole of a magnet you also have to ask where is the "-" pole because eventually it will become a factor.

The force between two positive charges varies inversely as the square of the distance between them. For example, if the charges are put 1 inch apart and the force between them is measured, and then they are put 2 inches apart, the force between them will be 1/4 the original force. It does not matter in what direction you separate the charges. The strength of the force is always the same and depends only on the charges and how far apart they are.

If the two positive poles of the magnet are sufficiently large compared with the separation, the force between them can be almost independent of the separation. However, once the separation becomes sufficiently large, the "-" pole of the magnet comes into play and the force between the two magnets varies inversely as the cube of the separation. This means that the magnetic force will always be weaker than the electrical force once the separation becomes great enough.

I wish I had a simpler answer for you, but electric and magnetic fields really are different. On the other hand, wouldn't it be boring if everything were the same?

Dr. Charles Smith
(May 2005)

First of all, one thing that is important to realize is that in the case of particle annihilation, the end result is always TWO photons. Imagine you were sitting in the center of momentum frame as these two particles annihilated. If only one photon could be produced, then it would be at rest in your rest frame. This is impossible since Einstein said that a photon must be moving at c = 300,000,000 m/s (186,000 miles/sec) in EVERY rest frame. If two photons emerge from the annihilation, this fact is not violated (the two photons can leave your rest frame in opposite directions at the speed of light).

Now, where does this momentum come from? As you may know, for regular particles that have mass, momentum, p is equal to mass times velocity. However, since a photon has no mass, momentum is redefined to be its energy divided by the velocity of light. This is a product of the Special Theory of Relativity. In fact, as a particle with mass moves faster and faster (and approaches the speed of light) its momentum gets closer and closer to its energy divided by the velocity of light. So for photons, energy and momentum are very closely related.

So as these two particles annihilate, the photons get their momentum (and energy) from these the particles. The faster these two particles are moving when they hit each other, the greater the energy of the two resultant photons.

Lauren Scott
(October 2003)

Plasma is made up of ions, which are charged atomic nuclei, with some or all of their electrons stripped off. Since charged particles bend and move around magnetic fields, it is possible to set up a magnetic field that will hold a group of ions (a plasma) in place. This is known as a magnetic bottle. Here, it is the magnetic field that is holding the plasma in place and not the walls of the enclosure.

Lauren Scott
(November 2003)