Loop Definition and 1000 Threads

1. A conducting loop is shrinking in a constant ##\vec{B}##-field that is perpendicular to the loop-axis. The radius of the loop is given by ##r(t)=r_{0}e^{-at}##. The resistance in the loop is ##R(t)=2 \pi \rho r(t)##. What force is needed to keep the loop shrinking like this?2. Faraday's law...

Background: Using Biot-Savart law we proved that for a closed loop with current ##I##, the magnetic field at a point P was equal to ##\vec{B}=-\frac{\mu_{0} I \nabla{\Omega}}{4 \pi}## where ##\Omega(x,y,z)## is a function of the position of P that represents the solid angle at which the loop is...

Homework Statement First of all, Happy New Year! I have to solve the following exercise (xmas gift :P) and some things are a bit vague..Here is it: For the ee--->ee scattering process, draw all amputated and connected graphs that would contribute. The hint is that one should find 10 different...

Homework Statement Actually, the main question is to find out the potential difference between the points 'A' and 'D'. The cell with emf 'E' has not been shown in the main question, but I have assumed it to be connected between 'A' and 'D'. Each resistor is of 1 Ohm. 2. The attempt at a...

Homework Statement A hypothetical magnetic field existing in a region is given by ##\vec{B}=B_o\vec{e}_r##, where ##\vec{e}_r## denotes the unit vector along the radial direction. A circular loop of radius a, carrying a current ##i##, is placed with its plane parallel to the X-Y plane and the...

A major change is happening in the way LQG is formulated. Suzanne Lanery gave a seminar about this 5 days ago (10 Dec) at Perimeter, and today she gave a similar talk at Nijmegen (Renate Loll's seminar). It's evident there is a lot of interest in this new development, which is based on the 11...

Hi Can anybody tell me where to put a PID controller in the picture below to design a voltage feedbaxk loop? Thanks

Homework Statement The problem states, "Find the electric field a distance z above the center of a square loop (sides of length a) carrying a uniform line charge λ. " The hint says to use the result of example 2.1. Example 2.1 is a similar problem, but instead of a square loop you are asked...

Homework Statement A program finds the area under the Gaussian Distribution Curve between ±σ using Simpsons Rule. Modify the program to investigate the effect of the number of strips. Do this by using a DO loop in the main program for the following sequence of number of strips (n); n-2, n-4...

Hi people, I have a problem with some integral here. I have a loop of radius a, with a current I = Ioe-iωt' and trying to calculate the radiating fields in the far zone, my procedement is: Current density: J(r',t') = Ioδ(r'-a)δ(θ'-π/2)e-iωt'/2πa2 φ (φ direction) Here t' = t - |r-r'|/c...

Homework Statement A roller coaster is on a track that forms a circular loop in the vertical plane. If the car is to just maintain contact at the top of the loop, what is the minimum value for its centripetal acceleration at this point? A) 2g downward B) g downward C) 2g upward D) g upward E)...

When I use the code directly below, it works (indicated by the "Out:..."). tmp2 = Flatten[{33, {1, 2 + j, 6}, 55}];(*Out:{33,1,2+j,6,55} *) tmp2[[4]]; (*Out: 6 *) But when I use it inside a loop, it acts like the tmp2 list is not the correct size: For[j = 0, j <= 5, j++, tmp2 = Flatten[{33...

How much of the standard model do we have to change/forget in order for quantum loop gravity to work?

hello guys iam doing my homework in magnetic fields course and i found this problem i solved (a) and (b) by using F=I L x B and the total force on the triangular loop would be zero but in (c) i tried a lot to find the torque on the loop but i couldn't get the same result so please help me...

Homework Statement A current loops is oriented in three different positions relative to a uniform magnetic field. In position 1, the plane of the loop is perpendicular to the field lines. In position 2 and 3, the plane of the loop is parallel to the field as shown. The torque on the loop is...

Consider this: We have a sphere rolling down a slant, released from some height h with null velocity. At the end of the slant its potential energy will have been fully converted to kinetic energy, part translational and part rotational. Now consider this: at the end of the slant the ball enters...

Disclaimer: I'm just an amateur enthusiast who is a programmer during the day I suppose everyone who takes an interest in physics who doesn't have the mathematical tools to further their enquiries end up writing posts like mine, and that at the very least it's nice to see where the ideas reside...

1. So the loop is known to be 12m in diameter (6m radius). Assume the car weighs 1250kg - how fast must the car go to clear the loop, and what will be its max G-forces endured? This was the question, which I have broken into 3 sections: a) Velocity at top of loop (done) b) Velocity at start of...

Is there a way to determine the profile of the field around a charged closed loop - particularly on the direction normal to the plane of the loop, both front and back? For generic values of V, I, B, H, etc., and any dimensions of the loop, any particular formulae possible to obtain? Thank you...

Homework Statement Calculate the vector potential of a loop with current ##I##, raidus ##a##. Calculate it for anywhere in space and use approximation where ##r>>a##. Homework Equations ##\vec A=\frac{\mu _0I}{4\pi }\oint\frac{d\vec l}{|\vec r-\vec{r(l)}|}## The Attempt at a Solution Ok...

Homework Statement Consider the loop in the figure below. What is the maximum induced emf in each of the following cases if A = 600 cm2, ω = 31.0 rad/s, and B = 0.490 T? Rotating about x,y,z? Homework Equations Faraday's law The Attempt at a Solution This should be relatively easy since the...

I have a multivariable function, z = f(x, y, w), represented by a surface plot in 3D (z versus xy) for each value of w. As w varies, the function z varies (goes up and down and changes shape) over a given rectangular xy region. As z varies with w, contour lines with given constant values of z...

Homework Statement A bar magnet is held above the center of a wire loop lying in the horizontal plane, as shown in the figure below. The south end of the magnet is toward the loop. After the magnet is dropped, what is true of the current in the resistor as viewed from above? (Select all that...

Homework Statement A magnetic dipole m is moved from infinitely far away to a point on the axis of a fixed, perfectly conducting (zero resistance) circular loop of radius a and self-inductance L. In its final position the dipole is oriented along the axis of the loop and is a distance z from...

Write a loop that sets newScores to oldScores shifted once left, with element 0 copied to the end. Ex: If oldScores = {10, 20, 30, 40}, then newScores = {20, 30, 40, 10}. Sample program: #include <iostream> #include <vector> using namespace std; int main() { const int SCORES_SIZE = 4...

Homework Statement Consider the figure on the right. Wire 1 is oriented along the y-axis and carries a current I1. A rectangular loop located to the right of the wire in the xy-plane carries a current I2. Find the magnetic force exerted by wire 1 on the top wire of length b in the loop...

Hi. In this video: he ignores the magnetic field from current 2(I2). Could anyone give me a good explanation why?

me and my colleague watched Mercedes Benz commercial where its sports car accelerated, went in a tunnel, and made a complete loop around the tunnel by going up against the wall. Now, the debate was on whether a car can manage to make a loop in a same tunnel with same given velocity entering the...

Say I have a scalar field which decays into to a fermion - anti fermion pair which then interact in a closed loop to produce two photons. How would I evaluate this? Can I just follow the loop backwards from any of the two photon vertices and just write vertex factor, propogator, vertex factor...

ok so i realized my problem with c++ is that i don't really understand for loops. well it's not exactly the loop itself but i don't understand the loop variable [i]. what is for EXACTLY? why is it needed? why can't you just use the other variable you are using? why does this extra variable need...

Okay, I have a simple plant which is 1/s*(s+1) Two poles on 0 and -1 and no zeros. This is the case for open loop. But when I close the loop with unity feedback and add a K gain, I end up with following transfer function; K/s^2 + s + K So, clearly the poles are now at somewhere else. However...

Homework Statement Find the currents going through each resistor. Homework Equations V=IR The Attempt at a Solution [/B] I have the problem worked out and I can't find any errors in my work. The issue is that my professor has: I1=-.0843 I2=.086 I3=.0017 However my physics professor is...

use the DO...WHILE...LOOP statement to blink an LED at a rate of 2 times a second as long as a push button is pressed. If the push button is not being pressed, the program should wait until the button is pressed and held before blinking the LED. To solve this problem, the DO...WHILE...LOOP will...

I am doing a project of theories of gravity, and am having some trouble understanding whether loop quantum gravity is testable or not. I had some questions which I cannot seem to find the answers to: 1. Is it theoretically possible to probe distances of 10^{-35} or would the concentration of...

Write an expression that continues to bid until the user enters 'n'. Sample program: #include <iostream> using namespace std; int main() { char keepGoing = '-'; int nextBid = 0; srand(5); while (<STUDENT CODE>) { nextBid = nextBid + (rand()%10 + 1); cout << "I'll bid...

Homework Statement A rectangular loop of wire, of sides 5 and 3 cm moves away from a a long straight wire at 4ms-1 carrying a current of 2 amps. What is the EMF induced in the moving loop, when the near side of the loop is 3cm away from the wire? Homework Equations B = μ0I/2πr EMF = -dΦ/dt...

what is the purpose of a loop variable (i)? how is it useful?

Homework Statement A small ball rotates in a vertical loop of radius R. it's velocity is the minimal required to stay in the loop. Now the loop is cut at an angle ##\alpha## and the ball shoots out of it. Express ##\alpha## so that the ball falls back into the loop and continues turning...

Getting confused on understanding how opamp works with zener in Feedback loop. Referring to the ckt here (attached.) (replace diode with 5V zener) Using virtual short, when the input voltage is zero, opamp output is 5V? Basically the opamp sources current into the zener. When the input is -1V...

Homework Statement A plane makes a vertical loop like in the drawing. the speed is exactly what is needed that at the highest point the pilot won't feel any force nor from the seat and nor from the safety belts. 1) what is the weight of the pilot in comparison to the airplane? 2) what...

I am not sure if this is supposed to go in the homework forum or not since it is more of an off physics topic so sorry if it is incorrect. I have a programming assignment for class and I am having a lot of trouble with a while loop. For this part of the program I have to prompt the user to...

Hello, I am a novice in Mathematica, but insisting to learn it. I would appreciate help in solving the following problem: (*a=1;Which[a==1,x,a==2,b]*) list := List[1611, 1612, 1613, 1614, 1615, 1616, 1617, 1618, 32, 10] For[i = 1, i < 4, i++, a = list[[i]]; Print[a]...

Does anybody know a good reference for the gluon propagator at two loop? I need it in Feynman gauge, but to have it in light-cone gauge as well is a plus. Preferably a paper, or a book that is common (i.e. easy to find in our university's library :-) ). Thanks!

Homework Statement The square loop shown below is made up of four identical wires of length scripted l = 18 cm each charged with a linear density λ = 18 nC/m. Find the magnitude of the electric field at a distance z = scripted l/2 above the center of the loop. Homework Equations...

There is a conducting circular loop with resistance R falling in the magnetic field \vec{B}=B_\rho(\rho,z)\hat\rho+B_z(\rho,z)\hat z and gravitational field \vec g=-g\hat z. How does z and the current in the loop change in time?(assume the loop remains horizontal!) The flux through the loop...

...based on the angle. Homework Statement Figure 30-78 shows a wire that has been bent into a circular arc of radius r = 24.0 cm, centered at O. A straight wire OP can be rotated about O and makes sliding contact with the arc at P. Another straight wire OQ completes the conducting...

This is a question currently pondered by many Quantum physicists and theoretical physicists. I was just wondering how many of you prefer ST(string theory) as opposed to LQG(loop quantum gravity.) Please provide points and reasons regarding your answer. I will provide an opinion when a few...

Homework Statement I have to write a C# program for an assignment for school. Programming is not a problem, but physics is :P So I am kindly asking you guys for helping me out with this.. Sorry for my bad english, I'm not a native speaker. A glider pilot starts a back-loop with a plane...

Homework Statement Hi, I am stuck on this thought experiment: A roller coaster of mass m starts on a inclined plane at a certain height, and then enters a circular loop, with radius r. At what height, h on the plane, must the trolley start in order to stop at the exact top of the loop...

Homework Statement (a) The metallic rectangular loop of length b and width a (ABCD) is mounted in an assembly, which allows it to be rotated about an axis bisecting AD and BC. The plane of the loop makes an angle θ to the horizontal and a uniform magnetic field B is applied vertically...