Recent content by worwhite

Great! Thanks for your insightful points Andrew :) I would like to ask about some of them in more detail though: 1. For a free expansion of a gas, could I consider it to be a special case where by w.d. = p(delta)V does not apply? My rationale is that since this equation is derived from...

Thanks for your replies. They agree with what I originally (and still) thought. What I heard must be wrong then... thanks again :)

Hi, just wanted to ask a simple question: In the following equation: Work done by gas = Pressure x Change in volume does pressure refer to the pressure of the gas (that is doing the work), or does it refer to the external pressure (i.e. pressure of the surrounding gas)? I've heard...

Thanks for the answer krysith - it makes sense to me I suppose. My original thought was that water at 100 C had slightly larger inter-molecular spacing (and thus P.E.), therefore it takes less energy for it to become gas compared to water at 10 C.

Hi, I would like to ask, why is it that the specific latent heat of vaporization of water at, say 10 degrees Celsius, is considerably higher that at 100 degrees Celsius? It would be great if you could provide an explanation from the molecular view. Thanks.

I see, thanks.

I must say I half-expected that response. Yes I agree that it's all too common in physics to have muddled definitions, and as you pointed out, especially so between fields. I was hoping that this wasn't one of those cases (and I'm still not convinced that it is). In any case, I certainly...

Ah so what you mean is that the band is partially filled, and you can call that either a valence or conduction band depending on the definition. "the definition" is exactly the problem I'm facing. I'm not sure what's the correct definition is for a valence band, and I'm seeking confirmation on...

Ah I think that gives me a much better picture. Thanks!

Thanks for your replies. I think I get the fact that metal does have its conduction band partially filled at 0 K. Yes in my search almost everyone (Wiki, hyperphysics etc...) says this. However, in some sources (and in the question I was doing), it is said that metal can have separate valence...

Hi, I understand for metals the conduction band is usually partially filled. However, at absolute zero, is the conduction band empty (for metals)? I'm asking this because as far as I know, the definition of valence band is "the highest occupied band at absolute zero" However, I have...

Hi, In studying about lasers, it was mentioned that lasers are highly focusable, and this was because of the high spatial coherence of lasers. Just want to ask: 1. Why and how does spatial coherence affect focusability? 2. How is a laser typically focused (using a lens?) 3. Why do...

Whoa, I didn't expect the replies to be so numerous. And I noticed my post is now under Quantum Physics rather than SR...apparently the mechanics of light interaction isn't simple at all... I have another question, though. Photons have momentum, though they have no rest mass. So imagine a...

Dale: "That's fine, but then you never get to the "massless" point that you were talking about. You still have a particle whose total relativistic energy consists of some KE and some rest energy (aka mass)." When I said that the "rest energy" of the subatomic particles contribute to the rest...

Hi, Just a simple question. Does anyone know how a photon interacts with say, a mirror? Does it bounce off the mirror, much like a ball does, or does it get absorbed and then re-emitted? Thanks.