Loops Definition and 275 Threads

As far as I can tell (if we look at pictures, without equations), a loop can be considered as a 1-dimensional closed string; and an open 1-dim string can be considered as a loop that we cut one point on its boundary? So basically the fundamental building block is the same whether you call it...

Consider the problem below I used Kirchoff's loop/junction rules to correctly arrive at answer C (1.3A). Before using Kirchoff's rules I tried to get ##V_3## by treating this as a Fermi problem using the following lines of logic, but there is a flaw somewhere, can someone identify the flaw...

I want some clarification on what is done about the ##\mu^{2\epsilon}## renormalization scale parameter in loop amplitudes. I am under the impression that it shows up to restore the mass dimension of an amplitude when the loop momentum integral is reduced from 4 to ##4-2\epsilon## dimensions. As...

Hi all, I have a question on the DC current flows, when two loops are close by. Consider a battery driving a loop with a finite resistance. There are charges on the surface of the loop, which exerts forces to direct the flow of the DC current. The changes also produce an electrostatic field...

Hello! (I am not asking for someone to do this for me. I am only asking a qualitative question.) Suppose one knows the lengths of all six links that are involved in the Stewart platform. Is that enough to define the position and orientation of the top (assuming the base is fixed) I would...

I am looking for a paper i read several yeais ago. is was on a graphical way to see all the closed loops associated to an oriented spinfoam. there was a set of lines on each edge. do you see what i mean? thanks

I was watching a video about a herpetologist's trip to Thailand to study monitor lizards and there was a short part of the youtube video showing a part of the wing of an aircraft this guy was riding in. It's obvious it was a jet plane, but there was these weird loops that appear to be welded to...

The standard configuration of Brunnian "rubberband" loops shows a series of unknots each bent into a U-shape, with their ends looped around the middle of the next unknot. (See for instance http://katlas.math.toronto.edu/wiki/%22Rubberband%22_Brunnian_Links). This connection requires 8...

str1="hello" for stringElement in str1: print("str1","=",stringElement) Strings are arrays in python and they are represented like this. Now I want to understand how the for loop is working here. My dry run-: for h in str1 print h for e in str1 print e and so on till...

I calculate like this and I think the answer is E not D. N( µoI/2a + µo2I/2*2a) = 2µoNI/2a = µoNI/a

DISCLAIMER: in Italy, we talk about "circuitazione" of a field through a closed loop ##\gamma##, for the physical quantity $$\Gamma_\gamma(\overrightarrow{E}) = \sum_{k}\overrightarrow{\Delta l_k} \cdot \overrightarrow{E_k}$$ but after some research, I haven't managed to find the correspondent...

Hi Pfs Marcus wrote a huge bibliography during many years about LQG. but i do not see where to find an answer to a question. Penrose draw diagrams with edges labelled by numbers. What is the reason why later number were replaced by SU(2) representations?tÿ

I was looking at this discussion of swapping roots of a polynomial causing the discriminant to loop around the origin. https://www.akalin.com/quintic-unsolvability Although it appears to be the case, has this mathematical fact ever been proven? It seems that the formula for the discriminant...

I'm in an intro E&M class, and I'm trying to distinguish between Motional EMF for loops of wire and conducting plates. This question might be kind of silly, but are Eddy currents pretty much the same thing as induced currents in a loop of wire? More specifically, what I am trying to ask is if...

I'm stuck straight out of the gate any help is really appreciated

It's a simple question, and I feel like the order in which you run two loops would not matter in regards to how long it would take to run the script. You'd still have to run through ##m \cdot n## cells no matter the order. If you check column-wise, you will have to check all m entries in each of...

Hello, When connecting different circuits together, the reference electric potential ##V_{ref}## (the ##0 Volt##) for each circuit should be the same electric potential so the potential at all other points is the same. If circuit 1 has reference ##V_{ref1}## and circuit 2 has ##V_{ref2}##...

I am trying to get more confidence on the direction of current using Amperes law, the problem statement is Loop1: My first task was to assign the direction of current. If I wrap around the my right hand fingers in the direction of integration the thumb is pointing up hence Positive Y direction...

Does this mean that the expression for the above vertex is $$ -\frac{g}{2}\epsilon^{abx}\epsilon^{cdx}\int d\tau \langle A_{a} (\tau) A_{c} (\tau)\rangle \langle Y^{i}_{b} (\tau)Y^{i}_{d}(\tau) \rangle $$

To find out what the induced loop current was i used the formula: V=R×I To find out what the value of V was i used the formula that links electromotive force (fem) to angular speed: Fem=ω×B×A The only thing that's missing is the loops area but considering that it's a semicircle and that the...

My attempt is the magnetic field due to loop1 and loop2 should get added The magnetic field due to loop1 is B1 =(μ0 * Φ * i)/(4*π*r) = (4*π*(2*π)*0.004) /(4 *π*0.015) = 1670nT. I assumed this value should be less than 100nT. What is the reason? The other question is "Loop 2 is to be rotated...

Please help! I am trying to create a Python program for an assignment that will convert Celsius to Fahrenheit and vice versa depending on the input from the user. The numeric conversion portion of the code is working, however, if the user inputs "exit" the while loop is supposed to terminate...

tree level diagrams are classical, and loops are corrections of order h. what is a good derivation or explanation of this?

I think I know the answer,but just to make sure. I have two coupled inductors through a core that provides better flux permeability, aka a transformer, I provide say 5v and 1000 amps AC to the primary loop, in my secondary loop I have a capacitor in series with the loop (of sufficient...

How does changing the core of the solenoid affect the current induced in the loop?

What's the difference between Closed Timelike Curves seen in physics and the time loops in movies where a character relives a period of time over and over, but retains memories? I'm just curious about this stuff.

I haven't been on here in a while and have forgotten a lot of my physics knowledge, which is annoying. I just want to know, are time loops possible? Like the ones that appear in movies where a character relives a period of time. Is this allowed by the laws of physics? I know it's not really a...

I wonder if there is a way to calculate induced EMF in closed loops around bar magnet, which is traveling with constant velocity v to the right as depicted?

Hi, If I understand correctly, closed time like curves (CTC) are world lines that close upon themselves. What would an observer measure to demonstrate a CTC?

Homework Statement Homework EquationsThe Attempt at a Solution The current in the inner loop should flow in anticlockwise direction so as to resist the increase in flux of the external magnetic field . But how do I deal with the outer loop since there is smaller loop inside it ? I think...

A causal loop is when an object has no definite starting point, eg: if you threw a ball into a wormhole, and when it comes out it hits itself, making itself go into the wormhole. This sequence keeps going. Is this kind of stuff possible if we ever have a time machine?

Hi PhysicsForums, I have a pretty basic question about extracting physical parameters from lattice QCD simulations. As described in "Quantum Chromodynamics on the Lattice" by Gattringer and Lang, it seems we should be able to extract the static quark/anti-quark potential by considering the...

Homework Statement I've recently watched a video which explains Kirchhoff's first law however, I'm not sure about his calculations. I got the same answer just wanting to make sure I am doing it right. the guy wrote L1: -75I2 +3V=0 ⇒ I2= -3/-75=0.04A He calculated L2 like -12V -125I3 +75I2=0 ⇒...

Homework Statement Homework EquationsThe Attempt at a Solution Call the middle point where the two loops meet O . The induced EMF in the right wire should be anticlockwise and in the left loop should be clockwise . But there can be only one current in the wire . The induced EMF in the...

I don't understand something. At the center of N circular loops, the magnetic field is μ_0NI/2a. And that for a solenoid is μ_0nI. Why are they not the same when the number of loops is large and the length for the solenoid is long?

Hello Everyone, Can someone please explain to me how I would go about verifying the External Static Pressure of a pump that feeds a pressurized fire fighting network with loops in it. An image of the network is attached. I'm not being able to grasp the concept of pressure drop in a pressurized...

Hey, I just thought I would share some of my video art. They are meant to be visuals going alongside Techno / House music in the nightclubs of Berlin. However I got a lot of ideas from reading up on physics, like diffraction patterns, fractals, polarization of light / materials, lenses, video...

Homework Statement Modification: Take two big loops kept on both sides of the small loop at a distance a from the corresponding end of the small loop. Homework EquationsThe Attempt at a Solution The flux through the bigger loop is equal to the flux through the smaller loop, provided that the...

I was just wondering, if time can be dilated by gravity, can it actually loop and repeat itself (like movies), and if anyone was there it somehow witness it, they would see everything repeated? Sorry if this sounds silly, but I'm curious.

Hello all, I am doing this question where it asks if I increase the tension of a two loop standing wave without changing the frequency, what kind of standing wave will I get? I came to the conclusion that it would become a one loop standing wave as f= 2L/(n) as I plugged in 2 for n and I got...

I'm not a math machine, but I dabble in dimensional stuff. I think this falls under knot theory. I have built several prototypes of a tesseract. Each of them sits in a little case in my office. One of them is made from truncated cubes, held together with elastic cord: In theory, the...

Hi. I am using the Hardy Cross method to simulate the gas flow inside a multiple hearth furnace (as shown in figure A). Figure B is a representation of the furnace's body as a pipe network. The segment A-AH represents the actual hEarth's, while segments B-AI and C-AJ represent the exhaust ducts...

“If the weak gravity conjecture is right, loop quantum gravity is definitely wrong,” said Nima Arkani-Hamed, a professor at the Institute for Advanced Study who co-discovered the weak gravity conjecture. source...

I was just wondering if there is any physics behind the time loops in the movies Groundhog Day or Edge of Tomorrow.

When you run current through a circle formed wire it generates a magnetic field. Will this field affect the current in the wire that generates it? I mean if it does wouldn't the calculations for the created magnetic field be rather circular? The magnetic field depends on the current which in...

I've come across a rumor that states that if-else statements can make the loops go slower. Well, it's not rumors since the writer offered numbers (times) to support the statement. http://blogs.sas.com/content/iml/2012/02/13/avoid-unnecessary-if-then-statements-in-loops.html I was wondering...

would be really grateful if someone could help throw some light on this - its probably really simple but I am typing myself up in loops! I have a piece of wire which is placed in an external AC magnetic field which is varying sinusoidally. The wire is folded to make two rings of radii r1 and r2...

Hello, well I am not sure how to search for this online, but I raise this question here: Suppose that I have several bins of let's say cuts, here I list 3 but the main idea is to make their numbers tunable by the user: cut1 = { "p10" : "p <= 10" , "11p20 " : "10<p && p<=20" ...

Hello, As a heuristic tool for a complex problem, I'm trying to understand a series of nested conducting loops each with a initial identical current on it. These perfectly conducting loops are in the same plane each with that current in either direction. Each nested loop is perfectly...