What is Current loop: Definition and 104 Discussions
In electrical signalling an analog current loop is used where a device must be monitored or controlled remotely over a pair of conductors. Only one current level can be present at any time.
A major application of current loops is the industry de facto standard 4–20 mA current loop for process control applications, where they are extensively used to carry signals from process instrumentation to PID controllers, SCADA systems, and programmable logic controllers (PLCs). They are also used to transmit controller outputs to the modulating field devices such as control valves. These loops have the advantages of simplicity and noise immunity, and have a large international user and equipment supplier base. Some 4–20 mA field devices can be powered by the current loop itself, removing the need for separate power supplies, and the "smart" HART protocol uses the loop for communications between field devices and controllers. Various automation protocols may replace analog current loops, but 4–20 mA is still a principal industrial standard.
Homework Statement
Consider a long wire running in the vertical direction with a rectangular loop of wire beside it as shown. Now suppose that a constant current, I, flows upward along the long wire, and the same magnitude current, I, flows clockwise in the loop.
As viewed from the top...
Homework Statement
Please see my attachment
Homework Equations
In the diagram, F1 and F2 are equal and opposite also F3 and F4 also equal and opposite.
Its been mentioned that F1 and F2 have same line of action of force and the resultant effect on the loop is zero. But F2 and F4...
Homework Statement
Revered members,
please see my attachment (1)
In this diagram, PQRS is a rectangular current loop and I is the current and its direction is shown in red arrow . B is the magnetic field and it acts from left to right and n is the normal drawn to the plane of the loop...
Homework Statement
Find magnetic field along the z-axis of a circular loop, radius R with constant current lying in the z=0 plane.
Homework Equations
vec(r) = vector of r.
zhat = unit vector z.
The Attempt at a Solution
So starting with the definition, B = (u_o I/4pi) (dl x...
Hi.
I have a question concerning the magnetic momentum of a current loop.
We know that if we have a circular current loop (a solenoid with N=1), there is a magnetic moment (mu) in the center of the loop given by "mu=S I" (I=current, S =surface enclosed by the loop). So, if there is an external...
Homework Statement
Here is the problem and the picture that goes along with it. I am really stuck because our teacher never explained a problem like this to us before. Any help is appreciated! THank you so much...
Homework Statement
A force acts on a rectangular loop of wire, pulling it out of a magnetic field. Calculate the force required to pull the loop to the right at a constant speed of 4.42 m/s.
B = 0.44 T
l = 0.350 m
v = 4.42 m/s
R = 0.356 ohms
Homework Equations
Fmagnetic=I*l*B...
Hi,
I was reading through Jackson's Electrodynamics trying to reason through example 5.5 for the vector potential of a circular current loop of radius a centered at the origin. I pretty much understand everything except when he defines the current density as
J_{\phi} = I\sin \theta'...
Homework Statement
"A closed circuit consists of two semicircles of radii 40cm and 20cm that are connected by straight segments. A current of 3.0 A exists in this circuit and has a clockwise direction. Find the magnetic field at point P (center of the figures).Homework Equations
B = (mu *...
Given a square loop of wire centered at the origin and the coordinate axes is such that x is the to the right, z is to the top, and y is through the page (or screen). The plane of the loop will lie in the x-y plane. There is a magnetic field in the x direction. If the loop is fixed on the y-axis...
1. Homework Statement
A) A current loop is placed in a uniform magnetic field that is directed out of the page as shown. The current is clockwise as shown. What, if anything, happens to the loop?
B) Consider the following rigid coil that is placed in a uniform magnetic field that is...
Homework Statement
A square loop of wire with side 0.60 m carries a current of 9.0 A as shown in the figure (http://img847.imageshack.us/i/springquestion.jpg/). When there is no applied magnetic field, the plane of the loop is horizontal and the nonconducting, nonmagnetic spring (k = 550 N/m)...
Hi all,
I have a certain problem I'm getting stuck on hopefully someone here can help
Homework Statement
A rectangular coil is 75 mm wide in the y-axis, 100mm long in the x-axis. What is the speed of the rotation if an rms voltage of 0,25 V is developed in the uniform field of B =...
Isn't exactly a homework question, but it seems like it should go here.
This is a page from my notes that I'm having trouble understanding. Basically, it's calculating the magnetic field of a dipole by considering a current loop and using the Biot Savart law...
Hi there,
a few days ago I derived the probably well-know expression for the magnetic field of a current loop including elliptic integrals of the first and second kind (it can be seen here http://plasmalab.pbworks.com/f/bfield.pdf" ). As I'd like to rotate and shift the position of the...
Homework Statement
Hi guys,
on chapter 14 in Jackson's classical electrodynamics, problems 24 asks to prove that a dc current loop does not radiate, starting from Lienard-Wiechert potentials for the individual charges q. The distance between them is \Delta.
We should move to the continuous...
Hello,
When I have a current loop (macroscopical, but I don't know if that matters) in an external magnetic field such that the loop's magnetic moment vector is not aligned with the magnetic field, I know it'll create a torque on the loop to align it with the B-field. I was wondering: does...
Homework Statement
[PLAIN]http://img521.imageshack.us/img521/5139/physicsproblem.jpg
Homework Equations
FM in uniform magnetic field = I L x B
m = I A2 where A is the area, direction given by Right Hand Rule (perpendicular to plane of loop)
T = m x B
The Attempt at a Solution
I need...
Hello
I am carrying out some analysis on the magnetic field generated over a 3D region by a single current loop. The present form of the equations is in cylindrical coordinates and is as follows
\vec{B}={Brc,0,Bz}
There is no angular component in this present from.
Note: The following website...
Hello,
I am having a bit of a problem with this classic example. I know about the symmetry but I would like to push through the math anyway. The field point is at distance Z from loop on Z axis. Using cylindrical coordinates I am at:
dH = I*(rho)d(phi)*a(phi) X (z*az - rho*a(rho)) /...
Homework Statement
It is important to be completely isolated from any magnetic field, including the Earth's field. A 1.00m diameter current loop with 200 turns of wire is set up so that the field at the center is exactly equal to the Earth's field in magnitude but opposite in direction. What...
[b]1. Homework Statement
A 4-20mA current loop is being used to transfer temperature
values in the range + 10ºC to +60ºC.
(i) What temperature is represented by a current of 7mA?
(A) What current would you expect when the temperature of the
sensor is 32ºC?
Homework Equations
i HAD AN...
Homework Statement
A current loop that lines in the horizontal plane consists of a straight line segment 2R and semicircular segment with a radius R. A current I flows through the loop (assume counterclockwise direction), and a uniform magnetic field B points outward of the page everywhere...
Homework Statement
Find the magnetic field of a rectangular current loop lying symmetrically on the xy-plane. Find the magnetic field at (0,0,z)
Homework Equations
Biot-Savart law or derived formula (Mu/4*Pi) * sin(theta2)-sin(theta1)/s
The Attempt at a Solution
I am NOT good...
I have a question regarding the similarity between the Biot-Savart law and the equation that gives the magnetic field inside a current loop, and the similar version of Coloumb's law that gives the electric field due to a charged ring. In the equation for a charged ring at...
Homework Statement
A rectangular 20 turn loop that is 12 by 5 cm carries a current of 0.10A. It's hinged at one of the longer 12cm sides. It's mounted with its plane at an angle of 33 degrees to the direction of a magnetic field of 0.50T. What's the torque about the hinge line?
Homework...
Homework Statement
Homework Equations
\vec B = \frac{\mu i \phi}{4 R}
The Attempt at a Solution
The field due to the curve R_1 is:
\vec B = \frac{\mu i \phi}{4 R}
\vec B = \frac{(1.26x10^-6)(.281)(\pi)}{4 (.023)} = -1.21x10^-5 \hat k
The field due to the curve R_2 is...
Homework Statement
A wood cylinder of mass m = 0.250 kg and length L = 0.100 m with N =10 turns of wire wrapped around it longitudinally, so that the plane of the wire coil contains the long axis of the cylinder. The cylinder is released on a plane inclined at an angle theta to the horizontal...
Homework Statement
A current loop in a motor has an area of 0.62 cm^2. It carries a 207 mA current in a uniform field of 1.43 T. What is the magnitude of the maximum torque on the current loop?
A = .0062 m^2
I = .207 A
B = 1.43 T
Homework Equations
F=(IA)Bsin(theta)
The Attempt...
Homework Statement
A circular coil of 720 turns and area 0.6 m^2 is in a uniform magnetic field of 0.63 T. The maximum torque exerted on the coil by the field is 0.0026 N · m.
a) Calculate the current in the coil.
b) Assume the 720 turns of wire are used to form a single-turn coil with the...
Homework Statement
A loop carries current I = 2.5 A in the x-y plane as shown in the figure above. The loop is made in the shape of a circular arc of radius R = 4 cm from qo = 60 ° to q = 360 ° . The loop is completed by horizontal and vertical sections as shown.
What is BA, the magnitude...
Homework Statement
Loop like an "O" with current moving to the left
Diameter = 8cm
Current = 15A
FIND THE FLUX DENSITY OF THE CURRENT LOOP IN THE PLACE OF THE LOOP?
Homework Equations
B(flux density)=F(magnetic flux)/A(area)
B=H(magnetic field strength)*Permeability
H(magnetic field...
Homework Statement
A rectangular loop of sides a = 0.3 cm and b = 0.8 cm pivots without friction about a fixed axis (z-axis) that coincides with its left end (see figure). The net current in the loop is I = 3.2 A. A spatially uniform magnetic field with B = 0.005 T points in the +y-direction...
Homework Statement
Find the magnetic field at the center of a square loop, which carries a steady current I. Let R be the distance from center to side.Homework Equations
Biot-Savart for a steady line current:
B(r) = μI∫ dl X r
---- ----------------------...
Homework Statement
A small current loop of area A = 1.5cm^2 carries current I = 3.6mA. What torque acts on it in a lab where its magnetic moment is perpendicualr to the Earth's magnetic field of
4.2 x 10^-5
(b) Find its angular acceleration if its rotational inertia about a diameter is...
given a current loop, centered at the origin, and tilted 90 degrees so that it enters at x=1 and exits at x=-1, carrying a unit amount of current, and completely disregarding the z axis.
is the strength of the magnetic field at any point in the xy plane proportional to 1/(distance from...
I am trying to calculate the E-field from a varying B-field. The B-field is from a current loop.
\vec{B}(\vec{r},t)=\vec{B_{0}}(\vec{r})Sin(\omega t)
where \vec{B_{0}}= http://www.netdenizen.com/emagnet/offaxis/iloopoffaxis.htm"
Now since B is varying with time there should be an electric...
Homework Statement
A 119 cm wire carries a current of 1.5 A. The wire is formed into a circular coil and placed in a B-field of intensity 1.9 T.
1) Find the maximum torque that can act on the loop.
2) How many turns must the coil have, so that the torque is maximized?
Homework...
Homework Statement
Assume that the current flowing into the loop is 0.500A . If the magnitude of the magnetic field is 0.300 T, what is torque , the net torque about the vertical axis of the current loop due to the interaction of the current with the magnetic field?
the loop is initially...
[SOLVED] Magnetic Field due to a current loop
Homework Statement
A single loop of wire of radius 3 cm carries a current of 2.6 A. What is the magnitude of B on the axis of the loop at 2 cm?
Homework Equations
B=\mu/(4\pi) * 2\pi(R^2)*I/(z^2+R^2)^(3/2)
The Attempt at a...
Homework Statement
Hi, it's my first post and I'm not sure whether it's the right category to post anyway. Please help me though :) I have to "construct" theoretically a superposition of magnetic fields for the introduction of my tokamak-related diploma thesis. First task was to find the...
This question is a little bit more difficult. I'm not too sure if I'm in the right place to be posting this type of question- but here it is:
Type: Theory Question regarding electromagnetism
My professor is an extremely difficult person to understand. His notes are all over the place and...
Homework Statement
If the current is increasing at a rate of 0.1 A/sec what would the induced emf in a loop of 0.5 m be?
Homework Equations
I = \frac{|emf|}{R}
emf = - \frac{d}{dt} B A cos(\theta)
I'm obviously missing an equation or something.
Some guidance would be much...
Hello everybody!
I have some trouble determinating the magnetic field generated by a circular loop of current. I'd use it as an approximation for the poloidal field in a Tokamak (field generated by the current in the plasma).
I tried using Biot-Savard's Law but I'm getting stuck... I hope to...
Homework Statement
The 2-cm (radius) current loop shown in the figure is changing from θ1 = 11 degrees to θ2 = 66 degrees in a magnetic field 2 T in 0.5 seconds. What is the magnitude of the induced emf to the nearest hundredth of a millivolt.
The wire in Problem 2 has a thickness of 1.04...
I have checked the forums for similar problems and have only seen that one would use 'MATLAB' to perform this integration.
All I want to do is find the 3 components of the magnetic field at a point (x, y, z) off of the axis of a current loop (given current, radius and that the loop lies on...
Another doozie for me. I have been trying this one for 3 days now. I will give my first born for help to this one :rolleyes:
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Calculate the magnitude and direction of the magnetic field produced at point P in Fig. 28.52 by the current I in the rectangular loop. (Point P is at...
I've given this one a good effort and I cannot seem to solve it, been trying for a couple days on my own now...Anyone able to lend a hand?
I was using t=uxB(u cross B) to find the torque and then take the negative of it to find the torque that is to hold it?
vector u = I(vector A), and for...