<p>crichessil, type out your question and maybe ill answer it.</p>
<p>the 2004 MC was released and available one month ago. if lucky, you can try to find someone who uploaded it online and print it out. but i doubt thay.</p>
<p>more questions on number 7 in 2000 free response, how do you know where the electric field faces (its number 7 b)</p>
<p>A hollow metal sphere of radius R is positively charged. of the following distances from the center of sphere, which location will have greatest electric field strength? answer is 5R/4</p>
<p>A) 0( CENTER of sphere)
B) 3r/4
C) 5r/4
d) 2r
E) none of the above</p>
<p>i do not know number 7 on 2000.</p>
<p>but the other question ...</p>
<p>the answer is 5R/4 by elimination. it cannot be 0 or 3r/4 because there is no electric field INSIDE the sphere.</p>
<p>E=kq/r^2</p>
<p>so from the remaining choices, the smallest radius will yield the largest electric field. (5r/4)</p>
<p>crichessill, i tried doing it with the radius equal to 1/4 and if you do it that waw then the force of gravity should be 16/10 times that of earth's. However, if you assume that your radius 1/2, then you do get the 3.92 which is about 4.</p>
<p>woo! just studied that, i kind of understand it now.</p>
<p>F = kq1q2 / r^2
E = F/q</p>
<p>so... plug in F, and you have E = kq/r^2</p>
<p>Can someone help me by explaining each equation? I understand F=kq1q2/r^2 is the force between two charges? [negative = attractive, positive = repelling force]</p>
<p>What about E = kq/r^2? The Force on a charge from an electric field? Im kinda confused.</p>
<p>for your second question, it will have to be the closest thing to the surface but it can't be anything less than r because inside the hollow sphere, no e field exists</p>
<p>i hope everythings learning from these questions coz i feel like a dumbass being the only one asking questions.</p>
<p>anyone care explaining the formulas for film interference (constructive/ destructive)</p>
<p>Lojt, that formula gives you the electric field around 1 point charge at a certain distance (r) away from it.</p>
<p>ooh so, the Electric Field's strength from a +4C chage, 3m away would be...</p>
<p>E= k(+4C) / 3^2 = 4k/9? What are the units? Coloumb's? Tesla? [Tesla's only for B-fields right?]</p>
<p>basically what constructive and destructive interference imply is that when there are two waves, if their peaks occur at the same time, essentially they will become one wave with a giant amplitude. They will "construct together." However, if they are destructive (maximum), the peak of one occurs at the low of another, cancelling each other out. Of course varying degrees of interference can occur which is what the formulas take into account.</p>
<p>can u relate it in film context? like when lights entering a film wiht a different n value what is the wavelength there.</p>
<p>electric fields are newton/ coloumbs</p>
<p>in film context, you just plug the various values into the eqn...n is just index of refraction</p>
<p>questionss</p>
<p>quantities that are conserved in all nuclear reactions include
I. electric charge
II. number of nuclei
III. number of protons</p>
<p>? im confused, cuz i know you have to balance both sides of the nuclear eq. to get = # of protons...but the answer's I. ..uhh...??</p>
<p>if photons of light of frequency f have momentum p, photons of light of frequency 2f will have a momentum of
2p << answer
radical2p
p
p/radical2
1/2p</p>
<p>i don't understaand...E=hf? lambda=h/mv?</p>
<p>A magnetic field of 0.1T forces a proton beam of 1.5mA to move in a circle of radius 0.1m. The plane of the circle is perpendicular to the magnetic field.
-- Of the following, which is the best estimate of the work done by the magnetic field on the protons during one complete orbit of hte circle?
0J << answer
10^-22J
10^-5J
10^2J
10^20 J
--Of the following, which is the best estimate of the speed of a proton in the beam as it moves in the circle?
10^-2m/s
10^3m/s
10^6m/s << answer
10^8m/s
10^15m/s</p>
<p>last one...</p>
<p>the disk-shaped head of a pin is 1.0mm in diameter. which of hte following is hte best estimate of the number of atoms in the layer of atoms on the top surface of the pinhead?
10^4
10^14 << answer
10^24
10^34
10^50</p>
<p>how do you know the direction of the electric field? for example on 2002 5a</p>
<p>and number 7a in 2000</p>
<p>electric field is always from higher potential to lower. It is assumed that the higher potential is positive while the lower is negative. Essentially electric field is in the same direction that a force qE would act on a positive test charge in between to parallel plate capacitators.</p>
<p>? what constructive and destructive equations.....</p>
<p>Maverick: "if photons of light of frequency f have momentum p, photons of light of frequency 2f will have a momentum of
2p << answer
radical2p
p
p/radical2
1/2p</p>
<p>i don't understaand...E=hf? lambda=h/mv?"</p>
<p>momentum = momentum [conservation of momentum]
mv = mv, and v = f(lamda)
so... mf(lamda) = mf(lamda)
so if you double the Frequency of one side, you have to double the otherside.
2mf(lamda) = 2p, where momentum=p=mf(lamda).</p>
<p>get it?</p>
<p>A magnetic field of 0.1T forces a proton beam of 1.5mA to move in a circle of radius 0.1m. The plane of the circle is perpendicular to the magnetic field.
-- Of the following, which is the best estimate of the work done by the magnetic field on the protons during one complete orbit of hte circle?
0J << answer
10^-22J
10^-5J
10^2J
10^20 J</p>
<p>magnetic field never does work because its perpendicular. also if the answer choice is zero and it has something to do with work, then thats the answer all the time i have encountered</p>