Flux Definition and 1000 Threads

Homework Statement Suppose you have a disk of radius r at x=y=z=0 with its normal pointing up along the z-axis. The disk radiates with specific intensity I(\theta) from its upper surface. Imagine the observer plane is at z=Z, where Z is much greater than r. Let I(\theta) = I = constant...

Hey All, I was wondering if anyone knows of any good simulation software packages that can do quantitative radiometry. I'm thinking COMSOL may have a radiometry suite, but I'm not very familiar with the software or package offerings. Basically, I'm trying to optimize the placement of hundreds...

When you have the both sides of a non-homogeneous bar with thermal conductivities k1 and k2 in contact to 2 different temperatures, can you consider it the same as if there was some flux going through a homogeneous bar with the weighted mean of k1 and k2 as the conductivity?

Hello everyone, For the past 4 years I have been working on a new type of musical instrument that fuses together elements from electronic music into the acoustic realm. The instrument consists of 26 strings inside a wooden enclosure that are actuated (or "bowed") by the use of electromagnets...

Hi, in an axial flux generator if the flux passing through any of the coils at any given time constant is in the same direction , can all the separate coils be connected in series as to create a single phase output? in permanent magnet rotor this would mean that the rotor disc facing from one...

I am fixed to find out the reason what makes the charges get separated in conductor causing an emf leading to induced current. A very good reason exists for motional emf. It can be explained with the help of F=qvBsinΘ.

How would I go about finding temperature distribution in a thin square plate during the the first few milliseconds (or actually a fraction of a millisecond) after t=0s. Initial temperature distribution throughout the plate is known, there is heat flux to one side = Qinj, while heat flux from all...

Suppose that a ferrite bead is put around a cable where a constant current I flows, just like in this image. The coordinate system has the z axis along the cable. Let's evaluate the current through the (x,y) plane: according to the Ampère's law, the only magnetic field component generated by...

Homework Statement A long, straight wire lies on a table and carries a current I. As the drawing shows, a small circular loop of wire is pushed across the top of the table from position 1 to position 2. Determine the direction of the induced current, clockwise or counterclockwise, as the loop...

The book I am working through is beginning to dive into induced currents and Lenz's Law. When a conductor is moving perpendicular to a magnetic field, the charge carriers inside will experience a magnetic force; This causes the charges to move. Eventually, the electric field from the charge...

Flux linkage in a wire coil is given by BANcos(theta) with B being flux density, N being the number of turns in a coil and A being the cross sectional area of the coil and theta being the angle between the normal to the plane of the coil and the magnetic field. Is anybody able to explain why it...

If we have a conducting loop, and a magnet (say North pole first) is pushed into it; that induces and emf and hence a current in the coil due to the changing magnetic flux, right? According to Lenz' law, the direction of the current is such that it opposes the change. So from the side the magnet...

I am looking to find the magnetic flux of a cylindrical magnet as it passes through a coil. I am aware of the complexity of magnetism, however, i am only looking for a conservative approximation of the magnetic flux. I found the formula ΦB = B · A, but is my understanding that the magnetic...

Hey All, I'm trying to design a solenoid that would generate about minimum 1.6 A of current in order for me to charge up a 1.5 A 1.5 V battery. I already designed one which is about 10CM in length and unknown number of turns (as I used a drill to wind the coils around it. so I would guess its...

Flux is defined as (Area Perpendicular to field) x (magnetic field). If a magnet is traveling through a coil of wires. How do you figure out the area perp to the field?

Hello. Maybe this is the one of the most typical example in Electromagnetism textbook. There is a single round wire carrying current I (in D.C) with radius of R and length is infinity. From Ampere's law, the B field inside the wire is B = μIρ/2πR2 aθ where ρ is radial distance from...

Homework Statement A rectangular coil is composed of 150 turns of a filamentary conductor. Find the mutual inductance in free space between this coil and an infinite straight filament on the z axis if the four corners of the coil are located at Homework Equations B = (phi-hat) μoI/2πr dS =...

So, I've been at this for a while now. I am using my textbook (Introduction to NE, Lamarsh) and I cannot find a solution to calculate the thermal and fast fluxes in the reflector of a critical slab reactor. I have only been able to find solutions for the spherical shape, even online. As I...

Homework Statement I came across a recent problem that asked me to calculate the flux density at the end of a solenoid. I was given the current 3 A , the number of turns per unit length , 12 cm-1 and the using the permeability of free space as 4π × 10^-7 Homework Equations The equation I used...

Imagine a ferromagnetic medium shaped as a cylinder (a ferromagnetic fiber) with a magnetic relative permeability of μr, tilted with an angle a, as shown in the picture. I would like to prove analytically that the sum of the inductances measured along the x-axis (angle is a) and y-axis...

i can not seem to figure out how is the magnetic flux is changing and thus the current is induced , "A "is constant (same disk is spinning ) and "B" is constant and does not change , so how is the current induced ? and more specifically how is the change of magnetic flux is happening ? thanks...

Homework Statement Considering the vector Field F(x,y,z))(zx, zy, z2), and the domain whose boundary is provided by S=S1∪S2 with exterior orientation and S1={(x,y,z)∈ℝ3 : z=6-2(x2+y2), 0≤z≤6}, S2={(x,y,z)∈ℝ3 : z=-6+2(x2+y2, -6≤z≤0}. Compute the total flux of F across S. Homework Equations...

Homework Statement A sodium lamp emits light at the power P = 130 W and at the wavelength λ = 570 nm, and the emission is uniformly in all directions. (b) At what distance from the lamp will a totally absorbing screen absorb photons at the rate of 1.00 photon /cm^2s? Homework Equations 1...

Flux is the no. Of electric field lines per unit area..how can it have a unit

Hi, I understand that magnetic flux is like electric current and will take the path of least resistance, but I really don't like the current analogy and here's one question where it doesn't help: Say you've got a piece of Ferro Iron where the magnetic moments are not lined up, you put a...

Consider a straight infinite wire that carries a current I. Suppose you place a square circuit near the wire such that the circuit and the wire lie on the same plane. The length of the sides of the circuit is l`. The nearest side of the rectangle is at a distance d from the wire. question is...

How much electric flux linked with the spherical shell having a hole?(consider the charge is outside the shell) I knew the flux linked with spherical shell is zero.(because it is closed loop.)

Homework Statement Hello, So I've got to evaluate a flux integral, but I get 0. Could someone please, check my workings and give me advice. Please find my workings and the problem attached here as an image. Thank you very much!

Homework Statement The initial separation of the pistons is 2cm. They are submerged in water at room temperature. I need to calculate the work required to have two pistons touch, find the volumetric flux of the water as a function of time, and the force at a given time Homework Equations...

consider the graph below, the bar of length ζ moving to the right with speed v in a uniform magnetic field B going out the page. i don't understand why does the textbook say that there is a change in the magnetic fluxΦ? i think the area doesn't change, although it's moving. the original...

Homework Statement Homework Equations Flux = ∫E.ds The Attempt at a Solution I need to get the projection of cone on a plane perpendicular to the electric field . The area thus obtained when multiplied by electric field would give the flux . I am not able to imagine the projected area...

I've been studying em induction and in my book it was explained by considering a metal rod of length l moving through a magnetic field and cutting through the field lines at a constant speed. So in time dt it moves through ds and they showed e=BA/dt, where A = l x ds(the area that the rod...

Homework Statement A circular area with a radius of 7.90cm lies in the x-y plane. A. What is the magnitude of the magnetic flux through this circle due to a uniform magnetic field B = 0.223T that points in the +z direction? B.What is the magnitude of the magnetic flux through this circle due to...

Homework Statement The following equation is presented in my textbook, with very little context and J is simply described as the "trans-membrane fluid flux, which can be modeled by using Darcy’s law." Typically in this bioseparations class, when we discuss permeate flux, it is a unit volume...

Homework Statement My book demonstrates how a uniform electric field through a box generates a net flux of zero. I was wondering if the same would happen from a point charge outside of the cylinder on one end instead of a uniform electric field. Homework Equations Flux = E⋅A The Attempt at a...

Homework Statement [/B] A simple model of a railgun is a metal bar which runs on two long parallel rails. The two rails are connected to a charged capacitor with capacitance C and a resistor with resistance R. After charging, the capacitor can discharge through the circuit. You may assume that...

I wasn't sure where to put this so mods feel free to move, So this is a problem I'm trying to solve for a masters project and simplified it is this; I essentially have a stack of magnets all separated by 4mm each magnet is identical and produces a magnetic flux of 17.5 gauss at its centre (all...

Hello, all. I have been working on the following problem and was wondering if someone could check my work and provide some valuable input: Here is my work: What do you guys think about my approach to this problem?

My reasoning: The magnetic force on charge q is Fm = qv x B B does not change |v|. Therefore, |Fm| is constant at time t > 0 and Fm is always perpendicular to the direction of movement of charge q. Fm behaves as a centripetal force, and thus the charge moves along the circumference of a...

It is a cylindrical ac machine. If we want to produce a sinusoidal voltage, we need B (magnetic density) to vary sinusoidally. To get B vary sinusoidally, we need to get H(magnetic intensity) to vary sinusoidally. To get H vary sinusoidal, the best way is to vary the numbers in the air gap...

I'm messing around with Faraday's Law of Induction, and I will be using two magnets attached either side to a small bar inside two coils of copper wire, which I spin to induce a current. The design is basically this: http://amasci.com/amateur/coilgen.html My question is, what shape for the...

Hello! Im having some trouble really understanding this concept. I'll summarize my difficulty in 2 situations that I struggle with: 1) Coil: The inductance of a coil with N turns is known to be proportional to N2. My question is why is that true? I know that the H-field (and therefore the...

Homework Statement Let ## E ## be the ellipsoid: $$ \frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}+z^{2}=1 $$ Let ## S ## be the part of the surface of ## E ## defined by: $$ 0 \leq x \leq 1, \ 0 \leq y \leq 1, \ z > 0 $$ Let F be the vector field defined by $$ F=(-y,x,0)$$ A) Explain why ##...

Measuring the total radiant flux with an optometer of SFH 4550 LED from osram I'm getting ~70mW, If I place 5mm long rubber hose around the led (top 2,5mm of the led is free), the power is reduced to 50-40mW. This does not make sens to me, the led has a half angle of ±3° and emits nothing to...

Hi, If you've got an arbitary magnetic Flux1 and Flux2, traveling in the same or opposite directions, through a core, it doesn't matter with regards to the point on the saturation curve does it? Opposing or in the same direction it'll still be at the same point on the mag curve won't it?Thanks...

I found that for some LED's manufacturers specify groups/classes of radinat intensity in their datasheets. For example SFH 4258 from Osram http://www.osram-os.com/Graphics/XPic0/00101891_0.pdf/SFH%204258,%20Lead%20%28Pb%29%20Free%20Product%20-%20RoHS%20Compliant.pdf has four groups, going from...

I understand that from KVL e = v -IaRa e=k(flux)speed speed=(constant)*(V-IaRa)/flux But physically what causes the speed to increase? What force causes the rotor to accelerate? In fact physically, the rotor is moving because of field flux interacting with armature current's flux. So...

Hi. Consider the cylindrical Gaussian surface (Gs) shown in the following picture: Using Gauss's law, ∫ E ⋅ dA= E ∫ dA = Q/ ε E 2 π r L = λ L / ε E= λ /(2 π r ε) Is this true? I have a feeling like this is wrong. We have considered that there is only ONE...

Magnetic flux linkage = BAN B=magnetic field strength per unit area A=Area of conductor moved through the magnetic field N=Number of coils I don't understand when my physics textbook says the area of a single coil of wire moved through the magnetic field is π×radius of coil^2 as most of the...

Homework Statement According to my textbook, the electric flux through a disk of radius R situated at a height d from the xy plane is given by: ##2 \pi k_0 Q [1- \frac{d}{\sqrt{R^2+d^2}}]## Where ##k_0 = \frac{1}{4\pi \epsilon_0}## I'm having some difficulty obtaining this answer. Homework...