22 Oct 07
Originally posted by RamnedOK! since I missed the spring question, I'm now on page 11 and will give this a whack! If we measured in proton volts, the resolution of our measurements would be courser by a factor of 1836 since a proton is that many times massier than an electron! Another way of saying it is the our measures of energy would not be nearly so precise!
Electrical Energy / Capacitance
[b]16. Suppose scientists had chosen to measure small energies in proton volts rather than electron volts. What difference would this make and why?[/b]
23 Oct 07
Originally posted by Gary Thomasnope 😉
OK! since I missed the spring question, I'm now on page 11 and will give this a whack! If we measured in proton volts, the resolution of our measurements would be courser by a factor of 1836 since a proton is that many times massier than an electron! Another way of saying it is the our measures of energy would not be nearly so precise!
I'll post the next question tomorrow
23 Oct 07
Originally posted by RamnedI think it must have a smaller frequency, and therefore less energy, because it has transfered some energy to the electron.
Quantum Physics
[b]27. An x-ray photon is scattered by an electron which is initially at rest. What happens to the frequency of the scattered photon relative to that of the incident photon?[/b]
23 Oct 07
Originally posted by RamnedThey are in the same chemical family. That means that all chemicals in a chemical family exhibit similar properties. The reason for this is that chemical properties (ionic charges, electron shell filling, bonding, are all related to the number of electrons and orbitals available for shedding or picking up or bonding in the outer shells, or sometimes, with transition elements, more complicated middle shells.
Atomic Physics
[b]28. (A) Why do lithium, potassium, and sodiu exhibit similar chemical properties? (B) Why is stimulated emission important in the operation of a laser?[/b]
Anway, lithium, sodium, and potassium are all highly reactive metallic elements that easily ionize (give up one electron) in chemical reactions.
24 Oct 07
2 edits
Originally posted by coquetteDon't forget part b. Part a is correct though.
They are in the same chemical family. That means that all chemicals in a chemical family exhibit similar properties. The reason for this is that chemical properties (ionic charges, electron shell filling, bonding, are all related to the number of electrons and orbitals available for shedding or picking up or bonding in the outer shells, or sometimes, with t ...[text shortened]... ghly reactive metallic elements that easily ionize (give up one electron) in chemical reactions.
24 Oct 07
Originally posted by RamnedPart b. Sorry. It was easy to overlook as the answer sounds too easy and circular. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. The characteristic of a LASER that is so important is that the light emitted is all "in phase." That is, the waves are running together at exactly the same time. All the little waves add up in power to one big . . or HUGE wave. So, "stimulated emission" is important because that is what causes all the light waves to be emitted in phase (all together). It's like in a school of fish or a flock of birds where they all turn together in the same direction at exactly the same time. We can't see why just by looking, but they do. One small stimulus causes them all to move together. It's just that in a laser it's millions of ions emitting together at the same time.
Atomic Physics
[b]28. (A) Why do lithium, potassium, and sodiu exhibit similar chemical properties? (B) Why is stimulated emission important in the operation of a laser?[/b]
24 Oct 07
Originally posted by coquettegood, i just threw that one in there 😛
Part b. Sorry. It was easy to overlook as the answer sounds too easy and circular. LASER is an acronym for Light Amplification by Stimulated Emission of Radiation. The characteristic of a LASER that is so important is that the light emitted is all "in phase." That is, the waves are running together at exactly the same time. All the little waves add up in po ...[text shortened]... her. It's just that in a laser it's millions of ions emitting together at the same time.
24 Oct 07
Originally posted by RamnedUnless I'm missing something obvious...
Nuclear
29. Two samples of the same radioactive nuclide are prepared. Sample A has twice the initial activity as sample B. How does the half-life of A compare with the half-life a B? (B) After each has passed through five half-lives, what is the ratio of their activities?
The half-life is dependent on the material. So the two samples have the same half-life.
In which case, the ratio of their activities does not change. After one half-life, A and B have both halved their activity.