Induced Definition and 977 Threads

Hi, Two questions I'm finding it hard to get my head around with inductors... Say we have an increasing current, this is going to cause an increase in flux in one direction, which will induce an emf to drive a current which produces a magnetic field to oppose the change in flux. Than doing...

∇x E≠0 for an induced electric field whereas for field produced by static charges we have ∇x E=0. This is a very huge difference in the property of a vector field,then why do we call both of them electric field ?

2. Three loops of wire move near a long straight wire carrying a current as in the following figure. (a) What is the direction of the induced current, if any, in loop A? a. clockwise b. counterclockwise c. No current is induced. (ANSWER) WHY IS "C" THE ANSWER? I don't understand...

Homework Statement There's a infinitely-long straight line in vacuum goes through space, carrying a current which is time-dependent. What is the magnetic field induced by the curent? B, vector, the magnetic field E, vector, the electric field J, vector, the current density ρ, scalar, the...

Hi, I'm a bit confused by induced drag on an aerofoil and hoping somebody can clear it up for me. I understand that as air slips around the edges of the wing due to the pressure differential between the top and the bottom surfaces, the angle of attack at the ends of the wings is...

All I understand clearly that if a metal sphere is charged then the charges must reside on the surface because that is the only way there is no electric field within the metal. However if you imagine a neutral metal sphere, and let's say it is suddenly enclosed by a uniformly charged metal...

Understanding the physics of "induced charge" over a perfect conductor When we put a perfect conductor, let's say a sphere inside an external electric field, there will be a surface charge distribution different from 0 even though the sphere is electrically neutral. I don't really understand...

Homework Statement The magnetic field shown in Figure P20.61 has a uniform magnitude of 29.00 mT directed into the paper. The initial diameter of the kink is 0.30 cm. (a) The wire is quickly pulled taut, and the kink shrinks to a diameter of zero in 55.00 ms. Determine the average...

1. A 400 V, 10 HP, 3-phase synchronous motor has negligible armature resistance and a synchronous reactance of 10 Ω/phase. The motor runs at unity power factor. Determine the motor line current and the corresponding induced e.m.f for full-load conditions. The efficiency of the motor is 85%...

1. A solenoid of length 3.64 cm and diameter 0.914 cm is wound with 170 turns per cm. If the current is decreasing at a rate of 36.3 A/s, what is the induced emf in one of the windings? this is what I did: Length of the solenoid l = 3.64cm = (3.64...

Hello Team, I have a rubber (harness A of 54 and elongation at break of 100%) on which 30N of force is applied over 45mm2 of ares. I would like to know the strain induced in the rubber against the force. The problem here is i could not find the exact Young's modulus value for this material. But...

conflict: why synchronous machine doesn't produce induced EMF in the DC field wires Isn't it current path through winding which produce magnetic field (rotating) the must produce EMF in the dc winding of field (same theory of induction) but why isn't true in synchronous

Can electromagnetically induced transparency, be effected on a single atom within a molecule? Thanks, Jake

Hey Folks, I am a third year electrical engineering student and just want to clarify a concept involving electromagnetics/transformers. When supplying magnetization current to a transformer (assume sinusoidal), this induces a time changing magnetic flux in the core. The time changing magnetic...

Do you need a magnetic field for EIT, or just two electromagnetic beams with the right attributes? Thanks, Jake

The question comes from the Munkres text, p. 133 #3. Let Xn be a metric space with metric dn, for n ε Z+. Part (a) defines a metric by the equation ρ(x,y)=max{d1(x,y),...,dn(x,y)}. Then, the problem askes to show that ρ is a metric for the product space X1 x ... x Xn. When I originally...

Homework Statement A long solenoid with 1000 turns per meter and radius 2cm carries an oscillating current given by (5A)\sin(100\pi t). What is the electric field induced at radius r=1cm from the axis of the solenoid? What is the direction of this electric field when the current is...

I've just got confused about how the induced current in a metallic ring is calculated. Consider a metallic ring (radius a, resistance R and inductance L) immersed in a oscillating magnetic field, which is oriented orthogonally to the plane of the ring. The variation in flux of magnetic...

Can electric field be induced at a point near a time varying uniform magnetic field? "Near" means not the in the place where magnetic field exist. But at a point outside the field's presence.

Homework Statement Suppose we have a toroidal solenoid with square cross section and whose axis of symmetry lies along the z axis. Suppose a current I(t)=kt runs through the solenoid. Find the induced electric field at an arbitrary point on the z axis. Homework Equations \oint \vec E \cdot...

Say you had a rectangular piece of conductor perfectly balanced on a central pivot point. Around it, you put something that causes an electric field throughout the region. On one end of the balanced piece, atomic cores get exposed as the electron sea rushes to the opposite side via induction...

Homework Statement A DC is flowing through a conductor LK. Homework Equations Will there be a current in the frame ABCD, when: a) The current in LK will be switched on and off. b) The frame will not move relative to the conductor LK. c) The frame will be dragged to the...

Hello. Say I have a single turn of a coil in an external magnetic field. How do I calculate the voltage induced in this turn ? Initially I would use Faraday's law ∇×E = -j ω B But what should I use for B ? Will B not be a combination of both the external field as well as the field...

First off, sorry if this is a simple question, I'm very bad at electromagnetism. Homework Statement A metal ring of radius R rotates with constant angular velocity ω about a diameter. Perpendicular to the rotation axis is a constant magnetic induction field \underline{B}. Find the EMF...

Homework Statement A technician wearing a brass bracelet enclosing area 0.005 00 m2 places her hand in a solenoid whose magnetic field is 5.00 T directed perpendicular to the plane of the bracelet. The electrical resistance around the circumference of the bracelet is 0.020 0 Ω. An unexpected...

What is the difference between induced electromotive force and counter electromotive force? The way they are generated seems the same to me. Can someone tell me the difference and how they are different?

Homework Statement Attached Homework Equations The Attempt at a Solution I'm pretty confused about this one. First, I thought that maybe the magnetic field's non uniformity didn't matter since the rate of change of flux was going to be the rate of change of area, but that's...

Homework Statement Introduction to Electrodynamics by Griffiths, 3rd ed. pg 141-2, Example 3.8: An uncharged metal sphere of radius R is placed in an otherwise uniform electric field E=(0,0,E). [The field will push positive charge to the northern surface of the sphere, leaving a negative...

I'm quite new here, but here's my question: Is there a way to make one magnetic pole stronger than another?

Homework Statement (See attached diagram)--Note this problem was taken from Barron's SAT Physics Practice Test 1 #58 As the loop rotates, the induced voltage will be maximum at... a) 0 degrees and 90 degrees b) 0 degrees and 180 degrees c) 90 degrees and 270 degrees d) 180 degrees and 270...

Not sure if this is in the right section, but anyway... Homework Statement Explain the primary cause of the force experienced by the rod. In your explanation you must refer to the magnetic field generated by the current. The rod is carrying current perpendicular to the magnetic field...

I am having some trouble understanding why and how the emf changes when a bar magnet is dropped into a solenoid. As the magnet moves down (have not entered the solenoid yet) it experences an increase in magnetic field. As it enters the magnet it experiences an increase in magnetic still until...

Homework Statement The following is Problem 1-13 on page 23 from Electrical Engineering Fundamentals, 2nd ed., by Vincent del Toro: "In the configuration shown in Fig. P1-13 the coil has 100 turns and is attached to the rotating member which revolves at 25 \frac{rev}{s}. The magnetic...

Has anybody thought of it before? I mean even if it were energetically expensive to harness it it might actually create more than it takes since the energy source is raining down from the heavens anyway. Such a power plant would have to be placed at a high altitude though because most cosmic...

We just went over Faraday's law in class and our teacher stressed how a changing flux is needed to induce an emf in some coil/loop/wire. I was just wondering then, how is an emf induced in a straight conducting wire moving at a constant velocity in a constant magnetic field? It seems as if...

Does photon has spin induced magnetic moment? I think the answer is no. But why? You know, electron has. Does this have something to do with the fact that electron is massive while photon massless?:confused:

1. A rectangular wire loop (length 60 cm, width 40 cm) lies completely within a perpendicular and uniform magnetic field of magnitude of 0.5 T. If the length of the loop starts increasing at a rate of 20 mm/s at time t = 0, while the width is decreasing at the same rate, what is the magnitude...

I don't quite grasp this statement : Open attachment to view the image of what's going on The field from a positive charge Q pulls electrons to the surface of the metal nearest Q, leaving a net positive charge on the surface farthest from Q. The fields of these induced charges resting on...

hi friends, Suppose we have a vector bundle E equipped with a hermitian metric h, and in a subbundle of E noted SE . I would like tocalculate explicitly the induced metric Sh defined on SE. How to proceed?

It's a routine to calculate the magnetic field between circular capacitor plates by the Ampere-Maxwell law, and it can be shown that the magnetic field increases linearly with the distance from the center of the capacitor plates, with direction parallel to the plates. But what if the radius of...

When a bar is heated evenly, and it expands freely, they say it has zero induced stress. How about the stored energy? Isn't some energy stored in the process of expansion? Can this energy be calculated the same way the elastic energy is calculated? If so, why we state that it has zero stress...

Homework Statement http://img831.imageshack.us/img831/9721/img20120725160304.jpg http://img542.imageshack.us/img542/653/img20120725160312.jpg Fig 1 is an AC generator Fig 2 shows 2 solenoids (ASSUME the area of coils in both fig1 and 2 are the same = A, resistance of 3-turn coils = R)...

Hi everyone: Since there are many ions in ocean water, and these ions are carried by ocean currents, and they are moving through the Earth's magnetic field, by the electromagnetic induction laws, wouldn't there be a induced electric field in the ocean? if i want to detect this electric field...

Hi, So, I am learning about induced emf. I am having a hard time grasping the idea that we are interested in the angle between the normal to the plane of the coil and the magnetic field. In the standard illustration I actually understand it, but the following question confuses me. We are...

I am reading Munkres book on Topology, Part II - Algegraic Topology Chapter 9 on the Fundamental Group. On page 348 Munkres gives the following Lemma concerned with the homomorphism of fundamental groups induced by inclusions": " Lemma 55.1. If A is a retract of X, then the homomorphism...

On page 333 in Section 52: The Fundamental Group (Topology by Munkres) Munkres writes: (see attachement giving Munkres pages 333-334) "Suppose that h: X \rightarrow Y is a continuous map that carries the point x_0 of X to the point y_0 of Y. We denote this fact by writing: h: ( X...

Homework Statement A square loop with side-length a is positioned at the centre of a long thin solenoid, which has radius r (with r>a), length l and N turns. The plane of the loop is perpendicular to the axis of the solenoid, find V_{emf} induced in the solenoid Homework Equations...

Homework Statement I want to know whether Eddy current and Induced Current are same? Homework Equations The Attempt at a Solution 1)When flux linked with a circuit changes, an emf is induced in the circuit and this emf is called induced emf and the current is called induced...

Homework Statement The book describes a rectangular loop of wire in a uniform magnetic field created by a pair of coils. It then discusses the emf that is produced when the rectangular loop rotates with constant angular velocity, noting that the induced emf varies sinusoidally with time. At...

If a neutral conductor gets an induced charge and is then grounded, will electrons from the ground flow into the conductors induced positively charged side, resulting in a net negative charge for the whole conductor?