# Search results

1. ### What is a photon in respect to electromagnetic waves?

I've always thought that photons and electromagnetic waves are one in the same. And I still do, but I'm trying to get a better grasp on the idea and am finding it difficult. 1) As I understand it, they are the same. But an electromagnetic wave with definite frequency is a perfect sine wave...
2. ### Any way to do this using simple matrix math?

Homework Statement The following notation is as follows: a comma ',' represents a column and a semi-colon ';' represents a new row. I have a vector: A = [a1, a2, a3, a4, a5] and a matrix B = [b1, b2, b3, b4, b5; b6, b7, b8, b9, b10; b11, b12, b13, b14, b15] What I want is...
3. ### Learning without being spoon fed? (mod, move please?)

Learning without being spoon fed? edit: thanks mods --------------------------------- Is there a source, or does anyone have an idea how I can learn Physics without being spoon fed? I feel like whenever we were taught something new in my college Physics, we weren't given a chance to come...
4. ### Finding reduced chi^2 for independent variable?

Homework Statement I have a function V = kI where k is some constant I_err = 0.005 A V_err = 0.00005 V A fit was then made, but a problem occurs when I try to calculate the reduced chi^2. Since the error of the dependent variable V is so small, the resultant reduced chi^2 is fairly...
5. ### What exactly is the amplitude spectrum of the Fourier Transform?

Homework Statement Not really a homework question, but related none the less. I'm confused about what exactly the amplitude spectrum is. As well as the power spectrum. Homework Equations Not really taking a purely mathematical approach here, I'm using numpy for python. Specifically the fft...
6. ### Thermodynamics: Gibbs free energy from this battery reaction?

Thermodynamics: Gibbs free energy from this "battery" reaction? Homework Statement I'm reading my text book and it gives an example. The dH of the reaction is -316kJ/mol so that much energy is released by the reaction itself. Additionally, the entropy of the products are higher than the...
7. ### Pulley with string attached to ground

Not exactly a homework question, but I need to know this before I can answer the question Homework Statement There's a pulley suspended from a rope A. Hanging from the pulley from one side is a mass m. "Hanging" off the other side of a pulley is simply the same rope (which is attached to...
8. ### Determine the following sets

I hate to do this, but I've actually answered the questions. It's just that it seems strange to ask the student questions with such answers, as well as giving so much space to answer something so simple, I feel like I've done something wrong. Homework Statement Let set Q represent all rational...
9. ### Triple Slit Experiment?

Suppose that instead of two slits for the classical experiment, we use three slits. First what pattern would appear? I tried drawing it out, but without a protractor to draw proper curves, it's hugely inaccurate and I'm too lazy right now. Anyway, to the actual meat of the question, I was...
10. ### Help with D-Type flip flops?

Homework Statement In the Feynman Lectures on Computing, he uses this as an example of a D-Type flip flop. http://img526.imageshack.us/img526/1490/dtypeflipflop.jpg [Broken] Where the boxes are comprised of: http://img228.imageshack.us/img228/7421/flipflopt.jpg [Broken] And the \phi^{1} is...
11. ### Question about interference by observation (double slit exp.)

In the double slit experiment, under observation, the electron acts like a particle rather than a wave. From my understanding this is because the photon that hits it for observational purposes adds enough energy into the system to affect the electron and make it chose one single path rather than...
12. ### How do I convert CC-NOT gates to OR operators?

Fredkin Gates are supposed to be universal. So far I've gotten AND, OR and NOT out of them but I can't figure out XOR. Any help? I know that A XOR B = (A AND NOT B) OR (B AND NOT A), but trying to recreate that with Fredkin Gates is not very elegant... is that the only way? Edit: I guess I...
13. ### What is the function of a collapsed wave?

What is the function of a "collapsed" wave? I know from observing the particle in a dual slit experiment the wave function collapses and the results becomes something like 2 lines, but is there a function that defines the two lines? Does it just collapse to a function of how the particles...
14. ### Differential Equations of form y'(x)=f(ax+by+c)

Homework Statement My professor states that a differential equation of form y'(x)=f(ax+by+c) can be reduced to a separable equation by substituting in v=ax+by+c, but I don't see how. Edit: more specifically: y'(x)= sqrt(3x -4y +2) Homework Equations y'(x)=f(ax+by+c) v=ax+by+c The Attempt at...
15. ### Good way to take physics notes?

Didn't know what section to really post this, but exam time approaches. And we all know what that means. That's right, procrastinate by doing the most mundane things just to avoid studying! Last year was adding lyrics and album art to every song on my iPod. Took about a good 8 days. This time I...
16. ### Trouble understanding matter as waves

For simplicity sake, I'm assuming an electron is travelling in just one direction (x). From what I understand the square of the electron's wave function is proportional to the probability of finding it at x. But there's a point in every period that the amplitude is zero, which means the...
17. ### Double slit experiment, observer effect

It was a good while ago since I heard about this particular experiment, but I remember vaguely reading about how in one instance they recorded the observations, but then deleted the data before anyone could look at it, and in that instance the wave was still produced. Thus showing that it really...
18. ### Energy of a massless particle

Homework Statement Show that if mass = 0, then E=pc and u=c. Homework Equations E^2 = (pc)^2 + (mc^2)^2 B = u/c = pc/E The Attempt at a Solution I understand that if m=0, then E^2=(pc)^2 => E=pc. But isn't p = Ymu? then: E^2 = (Ymuc)^2 + (mc^2)^2 Plugging in m=0 sets E=0... It seems...
19. ### Confused about the intergral over a sphere

I don't know the beginning part of the question is relevant, so I'll leave it out unless requested. At the point of: \intsin\varthetad\varthetad\phi Which is to be integrated over a sphere, when integrating from 0 to pi for \vartheta and then from 0 to 2pi for \phi, we get 4pi, which is...
20. ### The Elegant Universe (Nova Series) - Thoughts?

I just finished watching the "Elegant Universe" series recently, diving in hoping to be fascinated by the ideas behind string theory. Unfortunately, I left the series as more of a skeptic than a believer. First a disclaimer. This video is essentially where I got all my information about string...
21. ### Question about momentum and larger masses

Question about momentum and larger masses (ice tubing, and why we have to let go) Okay, so my friends and I went snow tubing recently where the track was as such: _ ..\ ...\<---hill ....\.............................................../...