Phenomenon Definition and 213 Threads

ok so I was creating a connection today and used a 5 v led on a 1.5 v battery. Battery was in a case from radioshack and had insulated leads, full of twisted micro wire. Since there was no way to crimp it or strip the wire without me ruining the twists, I just bundled it to some non twisted wire...

Where does the requirement come from that special relativity applies only locally? It is not immediately obvious from the two postulates. I'm asking because this is important for the validity of the Hubble Law.

Dear PF Forum, I'd like to ask a question regarding a post in Relativity sub forum. The formula for kinetic energy is ##E_k = 0.5mv^2## Which makes sense. Because if we push/accelerate 1 kg object for 1 m/s2 for 8 meters, we'll spend ##E = N.m = 8 joules## How much time do we need to do that...

There is the illusion that when a force is applied at one point on a spinning wheel, the effect is as if the force is applied 90 degrees downstream of the rotation. What is this called? Does it have an official name?

http://www.quora.com/How-can-sound-waves-alter-the-flow-of-water Ok, so I carried out this experiment, and I understand some of it, but need help with other parts. Ok, so are we actually seeing a sine wave formed by the water? If so, I understand that waves are supposed to transport energy...

ok. this may sound stupid, first of all i asked this question because i have a doubt that "if a photon can see things around it will it be able to see its own reflection if it aproaches towards a mirror?" so i played a video of light being reflected in a mirror in slow motion and paused the...

Hi, I find an interesting related to electric field when doing experiment. I put a chip which has the following circuit inside Scanning Electron Microscopy(SEM), an electron beam is irradiating on R1. The AC source is isolated from Earth by using a capacitor C1 and resistor R3 in the...

I'm not sure which forum to post this under... Anyhow all scientists I've talked to have agreed that sonoluminescence is not completely understood by the scientific community. I'm curious as to which parts of the phenomenon remain a mystery. To me it seems like a reasonable process if you...

Concerning Quantum Phenomenon: I understand the effects of liquid nitrogen on the magnetic fields. However If you ran a tube of liquid nitrogen in the center of a torus magnet or toroidal inductor - would the magnetic field increase, toroidal magnetic vector potential increase. (Zero-point...

The situation is probably well known by many of you. The setup is at rest realtive to the B-field while the rod is moving at a constant velocity. I have been thinking about the connection between the Lorentz force and Maxwell 3 and looking stuff up about it. The first question is wheither only...

I am a student in my third year of engineering (materials science) and I was performing a lab experiment in which I was asked to calculate the heat capacity of metals using thermodynamic relationships. The experiment was done by placing a metal sample into a foam container filled with liquid...

Greetings, I am a student in my third year of engineering (materials science) and I was performing a lab experiment in which I was asked to calculate the heat capacity of metals using thermodynamic relationships. The experiment was done by placing a metal sample into a foam container filled...

Suppose we have a random service time ##T## with residual service time ##R## observed at some point along the way. What is the correct way to call ##T## (in 1-2 words, without having to introduce ##R##) if: 1) For any observation time, ##\mathbb{E}R\leq\mathbb{E}T##? 2) For any observation...

Hello colleagues So I've been trying to make head and tail of a paper concerning coherence holography. As I see it, it involves a sound understanding of the Van Cittrt Zernicke theorem I have linked the paper below, and I was wondering if someone could explain the physics going on behind and...

If you have two hydrogen atoms as your system, then you use the many body schrodinger equation for 2 protons and 2 electrons. The coulombic repulsion between the two atoms is built into the SWE, so is there a range of different possible magnitudes for the repulsion? If so, does the system decide...

I have a long tube (aout 30 cm) with a convex lens of diameter 7.5 cm on the one end and a small hole of diameter 2 cm on the other. When i shine a light through the hole and let it pass through the lens, i get a flowery pattern on the wall, looked very strange to me. There is a maxima in the...

Hey! :o I am looking at the Gibbs phenomenon. We want to look at the behaviour of a Fourier series of a region of discontinuity of $f$, especially we are looking at the function $f(x)=sgn(x), x \in [-\pi, \pi]$ near $0$.Since $f$ is odd, it suffices to look its behaviour at $[0, \pi]$. Why...

When a substance is neither attracted nor repeled by a magnet what can I call such phenomenon? Thank you

Dear Experts, I am 4th year undergraduate who did experiments for drag reduction in swim cap. I had applied hydrophobic and hydrophilic coatings on my cap. My final results are shown in attachment below. The no cap has more drag than body with swim cap without coatings. There is not much...

Is there any real life phenomenon that can be modeled by the curve: S(t) = 1/(1+e^-t) ? in the range between t=-5 and t=5 Thanks!

maybe this is too basic question but it is not so clear for me. when we refer to a random experiment, can a phenomenon be absolutely random by itself or its all about our uncertainty about the outcome that we call it random?

Today, all of the scientific world (including /r/physics) buzzes about BICEP2's discovery of gravitational waves dating from Big Bang as an undispute confirmation of the general relativity. Now I wonder is it really GR? Can't it be explained by simple Newton's mechanics? I mean if you can...

Hello , I have a rather odd question. I am trying to find a phenomenon that occurs in nozzles but am quite unable to name the phenomenon per se. The vague description of the phenomenon I remember is that when a supersonic flow occurs in a nozzle (or superheated steam), there is heat produced...

Does the term "Coriolis effect" refer to the phenomenon that causes the sheering of wind (or other objects) due to the difference in angular velocity encountered when moving from north to south or south to north, or . . . does it refer to the turning observed with a Foucault pendulum that is...

Greetings all Over the last couple of days I have been delving into a new personal discovery about seismic waves. And with the talk recently in several threads in the general and classic physics sections about sound wave propagation in water, I thought this was appropriate to share. Many of...

Consider a wire with charges moving with speed 'v'and '-v' in frame F (with charge q at distance s away moving at speed u). In frame F', the charge q is stationary, and so the speeds of the charges in the wire are v+ and v-, where v- > v+ Hi guys, I have trouble following through the proof in...

A seemingly good way to understand the overshoot and decay (ringing) of a square wave on a scope is that it is the result of bandwidth limiting. In that case, the Fourier series of a square wave \Pi(t) = \frac{1}{2 \pi} \sum_{n=-\infty}^\infty \frac{\sin(n \omega/2)}{n \omega/2} \exp(i n \omega...

Why when artists mix blue and yellow colors, we see green? What is the physical explanation of this?

For some reason, can't delete this thread... thank you, UltrafastPED, the below video was very helpful!

is black hole a theoretical concept or a natural phenomenon?

Magnet Phenomenon: The "divergent" region of a ring magnet Here's a puzzler: I have a NdFeB ring magnet, 1.75" outer diameter x 1.375" inner diameter x 0.25" thick, N40 grade. It is axially magnetized so that the north pole is toward one face and the south pole is toward the opposite face. The...

What's the optical phenomenon called when a wheel is rotating clockwise so fast that it eventually looks like it's rotating counter-clockwise? Not a homework question, just curious.

Hello folks. 2-dimensional spectroscopic techniques have been used to investigate biological systems and found that they transfer energy via coherent pathways. However, some have argued that this has no bearing on how these systems behave in nature, as the sun is not a coherent source and the...

Here's an explosion from mythbusters. At about the 1:35-36 mark, there is a particular camera angle where if you go frame by frame, just as the explosion starts, there is a weird disconnected phenomenon right above the explosion(kinda like a cone). Could anyone explain what that is? A...

I have a bowl in my kitchen that turns black when heated (when it goes to the microwave oven or the washing machine). It is driving my crazy so I started to investigate. Here are the results: This is how it looks after cleaning it: After going to the microwave it becomes like this...

photoelectric effect is explained by taking photon of energy 'hv'.Even electromagnetic waves carry energy.Why can't they interact with electron and transfer energy ?Even a wave has characteristics frequency and wavelength charateristics and all. I think I'm a bit confused.Can someone help me...

Hi! Someone said me, if I take a plastic straw and wipe it with a handkerchief (or something like that), I can recharge it so that it will hang even on some of the walls due to electric charge (but do not know which way, tomorrow I am going to buy some straws:-D) How would you explain this...

I have read about effect of refraction due to slowing of light rays reaching the denser medium first and so light bends etc...but why can't light go as shown in the figure (attachment)? In the diagram (Sry, not a great artist ;-) ) the wavefront does change but not the path of light...or is it...

I'm not sure how to put it, but recently its been happening, so far around 3 times, i leave a glass or a lightbulb on my desk right between my screen and my speakers RANDOMLY, seriously.. SPONTANEOUSLY they EXPLODE They have NOT been exposed to mechanical stress or even rough...

Many years ago I was sat playing cards with friends when I saw this strange light outside hovering just above a door handle so I went to have a look. It was about the size of a golf ball and had some resemblance to a flame but with very different properties. It was silent. It was in...

[FONT="Arial"]My Question is, “why the phenomenon of relativity is not progressive in nature”. For example we say that a person moving with ‘c’ faces the time dilation say t. But since the person is still in inertial frame (constant velocity or zero acceleration) and also moving with ‘c’ with...

Can anyone give me a description of the beats phenomenon associated with musical instruments (or in general, any waves with which beats are associated). I have looked at numerous textbooks however I feel I don't completely understand the concept still. Thanks

Greetings everyone, When someone discusses a given topic, people often perceive that the speaker's view on the topic is opposite theirs, even if no opinion on the topic was given. I know that there is a technical term for this (I read it in an obscure magazine, like Alaska Airlines magazine...

So a human is made of cells. It is essentially a city or society of cells that live together. There is no such thing as human, it's just a bunch of cells. So human is just a natural phenomenon, an emergent property. In addition, a cell is just a bunch of atoms. I.e. a collection of atoms...

I am currently doing a bit of research into the history of our understanding of the solar magnetic field. It is quite interesting. As I understand it, sunspots, which were observed at least as early as the time of Aristotle, were the first solar magnetic phenomenon to be observed. Can...

is the phenomenon of rotation of planets best explained based on frame dragging due to sun? If so does universe rotate as a whole. What causes it. I am really beginner. Forgive my ignorance.

Turbulence -- just a phenomenon of cavitation? Is turbulence exclusively cavitation of a fluid? Please give me your insight on this idea.

Homework Statement I have to submit a photo for a physics contest. I was thinking of using the picture in the attached, but I'm having trouble trying to figure out how to explain it in terms of physics. The background on the picture is: We had a very wet snow and as the snow built up on top...

I boiled the milk in milk cooker and i opened once to take some milk out. Remaining milk was there in the cooker and cooker is tightly closed. I placed the cooker over the stove and stove is switched off. when i get up in the morning, i can see that cooker has fallen down from the stove..is...