June 2009 - Physics

<p>what about the one about Bohr model.
It seems to be that general consensus was the choice (the third i think) that says levels are equally spaced’
But technically, Bohr did not believe in existence of photon.
(Although definitely the answer would be ‘c’ the choice with energy levels being equally spaced)</p>

<p>For the transverse waves question, I believe that EM waves and waves on a string are transverse. Sound is longitudinal.</p>

<p>im pretty sure for the question with the loop in a magnetic field, there is still going to be a current induced in it and that it is going to be in the clockwise direction</p>

<p>@Fernando Morient</p>

<p>Did the question actually talk about photons or did it talk about the emitting of energy to move from one energy level to another.</p>

<p>all i remember is there is a mention of photon.
Well, its not really worth discussion i guess, since the energy levels are obviously not equally spaced
during the test, I foolishly chose 5</p>

<p>And for the electro-microscope one I wasn’t sure, I put magnetic field and looked online and saw that a STEM uses magnetized lens, but this other type of electro-microscope apparently uses a electron gun (a particle accelerator), but it works by utilizing a magnetic field.</p>

<p>yeah. i wish i knew what the question was so i could check it, since both seem like they could be right.</p>

<p>lol sorry to break it to u guys
but the problem with the square wire moving at a velocity through a magnetic field going into the page induced a counterclockwise current (there is flux because it’s moving)
you use the right hand rule
thumb to right, fingers into the page, curl fingers up, flows counterclockwise</p>

<p>actually
because the net magnetic field on the wire is not changing there is no current
because there is constant field in that area</p>

<p>if it was like the ap exam fq question with a changing loop
then yes there would be a current</p>

<p>well I assumed the the wire square was moving with a force to the left due to the current in the wire. Because f=Ilb, the current must be in the clockwise direction to create the force.</p>

<p>what remained constant in the spring one - force of gravity?
also, in the waves ones, which waves carry energy? I think I wrote sound and string - was there an option like that?</p>

<p>In the wire one, I wrote no current, cause I dont there was a change in flux -BA - since area wass constant.</p>

<p>guys it asked about ‘induced current’
what is the point if there was already clockwise current…</p>

<p>regarding the whole two sources in phase with a difference in the distance of one wavelength question…does anyone remember what the different answers were? I said it was the birghtest point, was there an answer that said it was just a bright part?</p>

<p>phi= (BA-BA)/t, no induced current if area and B stay the same</p>

<p>The Bohr thing said that electrons could move through different levels by emitting photons.
I think that’s right… so I put C too.</p>

<p>Wanna know something really stupid btw?
If you remember the question on “work”… (easiest question btw)…
I got up to realizing the d was 500 m and ma (force) also equals 500 N.
When I multiplied them I put 50000 and there was no effing answer which said 5x10^4.
It was only when I left that question and came back to it that I realized it was 250000.</p>

<p>■■■■■■■■ right? At least I got it, phew.</p>

<p>What was the answer to the quasars question? That it had been around since the beginning of the galaxy? Someone in this thread said that, but I don’t agree.</p>

<p>By any chance, would someone know the standard or general curve for the SAT II Physics?</p>

<p>were there two bohrs model questions?</p>

<p>The error one was definitely +/- 0.5. You just had to find the minimum and maximum values, and then found that the difference between them was 1. then you know that the error was +/- 0.5.</p>

<p>Im pretty sure all waves carry energy. I wasnt quite sure which waves could have interference. Its sort of hard to say for a string, because it sort of depends how you define interference. I thikn i put all 3 for that one too.</p>