Recent content by platonic

thanks to everyone that replied. my mistake was thinking that dl = - dr when in fact they are the same quantity, dl = dr .

true. taking E\bulletdl to be negative, the negative signs combine to give a positive. But E is inverse square in r. When you compute the integral in terms of r, you get an extra negative sign, which makes the potential negative. Integral of 1/r^2 is negative.

the potential difference between b and a is defined as follows: V(b) - V(a) = -∫E \bulletdl the integral is taken from a to b. so the potential of a positive charge, with infinity as reference, is V(r) - V(infinity) = V(r) = -∫E \bulletdl the integral is from infinity to r...

never mind. was using <-zl+y> for amplitude, when it should be the conjugate of that.nNow switch both i terms works gives me correct answer.

When you have i*e^(i@) as an amplitude, when you conjugate, do both i terms switch signs? I tried this and keep getting wrong answer. Thanks in advance. BTW this has to do with spin half particles.

I know that is the definition of work. But in computing that line integral, shouldn't integrating in from infinity be integrating along the direction of negative r hat??

dl (dot) r hat in computing potential?? when computing the line integral "from infinity" back toward charge, the direction is pointing to the circle. But r hat is pointing away from circle. So vector dl should equal magnitude dl times negative r hat, which would change sign of potential...?

There is nothing special about the dedection device other than the fact that it can be checked on by us as we make an "after the fact observation." Device is made of inanimate matter, just like everything around the slits. The innanimate matter of the detection device changes the behavior of the...

I added the last paragraph in "when observed emission by emission" myself. Initially there was no reference to two slits resulting when observed going into the slits.

Anybody have a reliable link with proof that observer effects behavior?

This little link here: says that if there is a detection device that observes the electron before it gets to the slits, the observation collapses the wave function. This leads to the electron behaving like a particle rather than a wave as it enters the slit, so two bands are produced on the...

may i ask what is your education level? I'm 3rd year undergrad and these problems are very difficult for me, whereas you knocked it out with no problems.

how do you find torque and angular momentum of hoop about that point? the com of rope is not moving with respect to that point, so it seems that torque and angular momentum about that point is zero.

I'm pretty good with linear algebra, the basics anyway. I took introductory linear algebra this fall. Eigenvalues/eigenvectors, bases and stuff like that I'm good with. I was planning on taking abstract spaces this summer before taking QM in the fall. The only reason I'm thinking about taking QM...

I'm sure there is a considerable jump in difficulty going from state to tech. Then in addition to that, the other students will have had a semester of class mech to further refine their problem solving skills. I guess I'll give it a try this semester, although I'm a bit apprehensive.