Recent content by Bravus

113 views, no replies. It's OK. Here's what I just tweeted: Work through physics problem I was stuck on. Reassured to discover it's impossible. Grinning supervisor confesses to being 'mean'. As far as I can tell, there's no way to do it with one particle. The hint and key, that we got...

A human EEG would be different enough from that of other living things (and non-living things!) to distinguish. Depends whether you can detect an EEG from a distance, i.e. without electrodes actually on the scalp, and through the box.

Not sure why the TeX is failing me on the equation, but hopefully you can see what is top line and what is bottom line. Edit: fixed that Second edit: I missed something on my earlier look. There is no c^2 term. It should have read V_{ac}^2 - as it now does.

Trapping dust particles in a Paul trap, in air, at 50 Hz (similar to Winter & Ortjohann, 1991). Gravity compensation is achieved using a DC voltage across top and bottom electrodes. Given the features of the trap, the charge-to-mass ratio of the trapped particle can be calculated as follows...

Yep, that works, thanks! (As ever, it looks easy once someone explains!)

Homework Statement Here's a link to an image of the exam question. It appears in the exam every couple of years, and it's due in my exam this coming week. I've looked in both the textbook and the course notes, and they simply *state* the conclusion, so I don't have a way of proving it, and...

Thanks, yes, excellent!

Thanks, Francesco. That kinda makes sense to me. But I'm a little unclear. The fact that A and B commute means there *exist* simultaneous eigenkets, |ab> of both A and B. I don't think that means, though, that |a> and |b> are *necessarily* all simultaneous eigenkets. And they would...

Homework Statement http://www.bravus.com/question.jpg Homework Equations See below The Attempt at a Solution Below are my scribbles toward a solution. The point is that the two expressions are different *unless* either the operators A and B or the operators B and C commute...

Thanks but never mind: a and b were being calculated correctly (I was misled by something else), and E just needed an extra set of brackets to sort the calculation order.

http://www.bravus.com/formulae.jpg

(The usual format doesn't really fit this question, so I hope you won't mind if I set it up slightly differently) The task is to make a Fortran program that will read in a given set of data from a file, stopping when it reaches the end, and calculate the gradient and intercept of a best fit...

This works: rexact2=exp(x) i=1 dxfact2=1 rdiffer2=100 ! DO WHILE (rdiffer2>dx) ! dxfact2=dxfact2*i rapprox2=rapprox2+((x**i)/(dxfact2)) rdiffer2=abs(rapprox2-rexact2) i=i+1 ! END DO ! Thanks heaps, well done!

The challenge, though, is that I don't know n. There is no specific number of times to work through the loop, it just needs to run until the difference between the approximation and the actual value is smaller than a certain number.

Aha! Yes, that'll work. Didn't get what you did... and then I did! Was thinking I had to run a loop from 1 to i each time to calculate the factorial, but of course I can just keep building on the factorial each time. And yeah, forget the lecturer... I'll go for simpler variables, stop...