<p>how do i know charges are moving up? </p>
<p>because magnetic field is pointing in the page, and as the rod moves to the right, flux is getting bigger, so lenz’s law creates a CW current that will create a ‘weak magnetic field’ coming out of the page to try to oppose the string’s increase in flux… therefore, CW current is a charge moving up the bar. RHR says moving up, pointing in the page, you get a force to the left.</p>
<p>Wow, I totally bombed number 3. And 7, for some reason. ??</p>
<p>…let us now speculate on the curve. More lenient than usual? I hope so.</p>
<p>I see what you’re saying but why is the flux getting bigger? If flux is given by BA cos theta, which one of those is changing as the rod slides to the right?</p>
<p>area is changing, lol</p>
<p>What did you guys get for the last problem (#7)?</p>
<p>hey guys!! do the ap graders go easy on us??
for example, with number 3 frq, i numerically got parts a, c, and e correct, the other missed parts were due to an incorrect numerical calculation for part b</p>
<p>and for the thermo question, i did everything right, used right formulas, EXCEPT i just assumed there was one mole, which in the end basically made my temperatures wrong…how the graders handle this? would they think that i should’ve have had enough common sense to figure out that there was more than one mole? so they won’t give me any credit?? or will they have mercy??? =/</p>
<p>please reassure me!!</p>
<h1>7:</h1>
<p>a)they told you the de Broglie wavelength of the electron, so
p=h/lambda…mv=h/lambda, you know mass of electron, h, and lambda b, solve for v.
once you have v, Ke=1/2mv^2.
b)Kmax=hc/lamda-workfunction
you know Kmax, you know hc and lambda of photon, solve for work function.
c) since E= hc/lambda, then we know a bigger energy means smaller wavelength, right? so the only “bigger energy” than x are d and e… but since the photon is coming IN, then it’s path ‘e’</p>
<p>I’m fairly certain that they only take off for an error once–i.e., they will take points off because you assumed that there was only one mole, but only for the first incidence of the mistake.</p>
<p>…or maybe that’s just my wishful thinking.</p>
<p>Pigs at sea: They do not propagate errors, so if you make a chain of mistakes, they will only count it as one.</p>
<p>^phew thank goodness, because i also did this on number 7 lol
so is the energy transfer e for #7???</p>
<p>yes, it’s e.</p>
<p>for the electric potential equation (number 2 part b). Did u guys use v=kq/r for the formula and then made it into v=2Q/(Tsinx) i think</p>
<p>yeah, but I made r = 2Tsin(L)…oops. Maybe I didn’t…</p>
<p>oh, i think r=T(sinL) since that is the distance of each charge away from the middle point.</p>
<p>frq #2</p>
<p>part d)
i had
Tcos0=mg
Tsin0=Fe <—was i supposed to expand Fe? the question was too unspecific. i could have done that if it wanted that =[…how many points do you think they’ll deduct??</p>
<p>beautiful, thats what i put (thank god for FBDs), but i just in case i put on the side Fe=q^2/(2sin0)</p>
<p>I totally expanded it and SOLVED IT (no numbers of course…) when it said not to =(</p>
<p>you guys misread number 7c. It asks for the electron transition that caused the incident photon. When electrons drop energy levels they emit a photon. Therefore its d, not e.</p>
<p>just reading the questions no pigsatsea, they won’t take points of b.c u labeled it on the fbd which was the question before</p>
<p>I agree with YourFired (mainly because that’s what I put…) :)</p>