The tag has no wiki summary.

learn more… | top users | synonyms

1
vote
1answer
156 views

Induced electric field due to a moving wire

An infinite wire carrying a constant current $I$ in the $\hat{z}$ direction is moving in the $y$ direction at a constant speed $v$. Find the electric field, in the quasistatic approximation, at the ...
0
votes
1answer
103 views

Pulling a bar through a magnetic field

This is a question on magnetic flux and induced voltage. I believe that this problem's answer key is incorrect, and I want to determine whether my opinion is sound. I also want to explore one ...
0
votes
2answers
31 views

Inductor - cause and effect [on hold]

The voltage on an inductor due to alternating current, also called back emf, is given by a beautiful, simple equation. It's just L times time derivative of current. According to Kirchoff voltage law, ...
-3
votes
2answers
65 views

What is induced current? [on hold]

Can someone please provide me with a detailed, elementary explanation about the principle of induced current in electromagnetism.
3
votes
2answers
168 views

Is light moving because of self induction? [duplicate]

Light is made by an electric field wave and a magnetic field wave. Induction laws state that a variation in the electric field creates a magnetic field and vice versa. Therefore can it be said that ...
0
votes
1answer
321 views

Magnetic fields in transformers and back emf?

i am having some trouble with understanding the magnetic fields inside transformers and how they relate to back emf. My first query is: is the magnetic field produced inside the soft iron core ...
0
votes
0answers
18 views

Approximate of self-inductance of a square wire coil

Imagine you have a square coil of wires with n turns. In order to calculate the self-inductance coefficient I should know the magnetic field. Is it acceptable to consider the 4 sides as infinitely ...
4
votes
3answers
939 views

Measuring voltage drop from induced current

I'm having trouble connecting voltage drops and induced current. Imagine you have a triangular loop make up off three resistors. You place this loop in a constantly changing magnetic field. This ...
0
votes
2answers
156 views

Why Change Of Magnetic Flux Induces Current In circuit?

Why change of magnetic flux with the time through a coil induces current in it? Please tell me that what happen to charge in the coil if the magnet or electromagnet wave around this? Also, why a ...
2
votes
1answer
13 views

How do NFC/RFID devices transmit data?

I am designing an NFC device but am still a little unsure about the principles behind NFC/RFID. From what I understand: A primary coil constantly emits a 'carrier frequency' magnetic field. This ...
0
votes
2answers
192 views

Currents induced by rotation of a coil about magnetic field lines

If the coil on the left is rotated about the magnetic field lines, will there be an induced current? I know that the flux concerns only the component of the magnetic field perpendicular to the ...
1
vote
3answers
83 views

Does an induction cooktop consume as much energy when it's heating something as it does when it isn't? [closed]

If you plug in an electrical charger or an adapter of an electronic device such as a mobile phone or a laptop into the power socket, but you don't actually attach the device into the charger, the ...
0
votes
1answer
152 views

magnetic field of a rotating ring magnet

Can the magnetic field of a rotating ring magnet induce current in a conductor? Is there a flux linkage between magnetic field of a rotating ring magnet and a conductor?
0
votes
3answers
107 views

Induction on a circuit with switch

I have the following circuit: It is subject to a steady, time-invariant magnetic field which points out of the paper. At $t = 0$, the switch closes. I thought that the magnetic flux would decrease ...
0
votes
2answers
385 views

Is it possible to use induction ampermeter to measure power consumption of electric water heater and dryer?

I hope this practical question is not OT and not too trivial for this forum. I am renting an apartment in a duplex with a shared water heater and dryer. Turns out, both water heater and the dryer are ...
3
votes
1answer
158 views

Magnetic Levitation : Confusion with Lenz's Law

Considering the above diagram, I am failing to see why the aluminium ring floats upwards rather than oscillates. I understand Faraday's law, but I am struggling with Lenz's law - as there is an ...
0
votes
4answers
86 views

Can the potential difference produced in Van De Graff generator used to generate electric current?

If this machine can build up high voltages of order of millions of volts, can we use this volt the generate current of electrons? The building up of potential difference can result in electric field. ...
3
votes
2answers
173 views

What is the area in Faraday's law if we have only a piece of metal moving in a magnetic field?

If a piece of metal of length $l$ is moving with a speed $v$ in a region where there is a uniform magnetic field $B$ perpendicular to it, there will be a potential difference across its terminals ...
3
votes
2answers
209 views

Why is there no induced electric field in the experiment (Faraday's Law)

Below are three circuit diagrams for each of Faraday's experiments that allowed Faraday to come up with Faraday's Law. In Griffiths' Introduction to Electrodynamics Griffiths states (on page 302 of ...
3
votes
4answers
89 views

How does an inductor store magnetic energy?

I am trying to figure out what the potential energy of an inductor with a current really means. In a capacitor, the energy stored works like this: if you let the plates attract each other, before ...
-2
votes
0answers
51 views

How it is predicted, that a moving charge has to have a magnetic field?

This question appears after this comment: Even electric charges without intrinsic magnetic dipoles moments produce magnetic fields when they move. My respons: All electric charges (electron, ...
0
votes
1answer
95 views

Back EMF & Current, how can we make the current $I$ stable?

Lets assume we have a wire that has $10V$ across and $1$ $Amp$ flowing, now if this conductor is introduced to a changing magnetic field, $-EMF$ is induced, can we control our voltage to increase it ...
0
votes
1answer
119 views

Measured voltage on coil

I have a simple circuit of coil with inductance L $$u_c(t)= -L\frac{di}{dt}$$ and AC source with output voltage $u_s$ What is actually measured by the voltmeter ($u_c$, $u_s$ or $u_s - u_c$)? If ...
0
votes
1answer
103 views

Asymmetry in magnetic field direction of an electric wire

The simplest magnetic field is that of an infinitely long wire with uniform current. It does enjoy radial symmetry about the wire and has the variation as 1/r. To find the direction of the resulting ...
1
vote
2answers
247 views

Faraday's law and “infinite induction”

I may have confused after thinking too much about Faraday's law. If an emf is induced in a circuit due to some changing magnetic field, the induced current will be in a direction such that the ...
0
votes
1answer
55 views

Books on Faraday, Maxwell

Can you recommend a/some good book(s) on Faraday for the lay person? In particular, in relation to his 'Experimental Researches in Electricity'. Also, any books explaining how Maxwell explained ...
0
votes
1answer
33 views

Two questions about the nature of induced emf

I have two questions about magnetic induction (I am in university level introductory E and M so maybe my questions will be answered over the next few years): In the linear generator (shown below), I ...
4
votes
4answers
310 views

Can current be induced in a superconductor?

Moving a magnet close to a conductor induces a current. If it consists of a superconducting material with resistance $R=0$, then my textbook says: Then the induced current will continue to flow ...
3
votes
1answer
47 views

Does an Inductor maintain it's energy?

Consider a simple LCR ac circuit; generally I (might) understand that the charge exchange between capacitor and inductor would induce a harmonic current flow, but I remain confused for two reasons: ...
0
votes
0answers
13 views

How to show laminations minimizes eddy current?

In transformer, lamination is an effective method to minimize eddy current and thus energy loss. I just wonder how can we show that the energy loss due to eddy current in those laminates is added up ...
0
votes
1answer
72 views

The image current due to moving charges and a current carrying thin wire

Suppose we have a plane conductor and positive charged particles of mass m are moving parallel to the plane conductor at a distance d. The trajectory can be assumed to be straight. An image current ...
1
vote
1answer
28 views

Does the wireless energy tranmission affect compass

Wireless energy using magnetic inductive coupling. So magnetic field will be affect around device. We use it to charge mobile device so I wonder if it will affect compass in our device
0
votes
2answers
195 views

Magnetic field by a solenoid?

I am really not able to understand why is it that the current,while finding the magnetic field in the solenoid (ideal one), is not $I$ the current flowing throught the solenoid but $nI$, where $n$ is ...
1
vote
2answers
270 views

Derivation of Faraday's law using Lorentz force?

For a stationary loop of wire with a time varying magnetic field $\vec{B}(t)$ through it. Is it possible to derive Faraday's law, using only the Lorentz force $$\vec{F}=q \vec v\times \vec B \tag ...
7
votes
1answer
7k views

Does a positive or negative charge attract a neutral object?

Three objects are brought close to each other, two at a time. When objects A and B are brought together, they attract. When objects B and C are brought together, they repel. From this, we conclude ...
1
vote
0answers
27 views

Uniform field through a disc

Let us say that we have a magnetic field of the form $B_0 \sin(\omega t) \hat e_z$ in all space. Now let us say we put a conducting disc within this field. I want to find the electric field within ...
0
votes
0answers
17 views

Electric potential at the wings of a plane

PROBLEM: A plane with wing span 70 meters is flying with a speed of 100 m/s in a uniform magnetic field B = 5 T that is directed vertically with respect to the wingspan. What is the emf produced ...
0
votes
1answer
44 views

Inductance of two parallel wires

I've been asked to calculate the inductance per unit length for two wires or radius $a$ separated by $2d$ where $2d>>a$. Starting from $\int_{s} B.dS = LI$ Im not sure what surface to take? ...
2
votes
1answer
104 views

What is the sum of the electrons' magnetic moments in a wire?

Electrons have magnetic dipole moment. This magnetic moment will be influenced in an electric field in case the electron get moved non-parallel to the current. The magnetic moments will be more or ...
4
votes
1answer
57 views

Why an inductor parallel with a light bulb makes it flash as a key closes the circuit?

The title is a simplified form of my question. To be precise, I'm talking about the following circuit: The inductor has a resistanse equal to the resistor in the circuit. So, the question is that, ...
1
vote
1answer
314 views

Why is there a voltage drop across a superconducting inductor?

If there is no electric field inside a perfect conductor, then why is there a potential difference across an (superconducting) inductor?
1
vote
0answers
20 views

Calculating the amount of charges for an object that is electrostatically induced

Induction is one of the ways to get an object electrostatically charged. While positive charges accumulate on one side, negative charges accumulate on the other side for an object in an electric ...
1
vote
0answers
68 views

Induced e.m.f depends on…?

In my revision guide it says that Michael Faraday did experiments that showed that induced e.m.f for a coil of wire depends on four things: Magnetic strength of the core in the coil of wire. ...
4
votes
3answers
417 views

How are the Lorentz force, Maxwell's third law and Faraday's law of induction clasically related?

Faraday's law of induction can be used in any situation where the magnetic flux is changing through a closed conducting loop. While giving the correct answer, it seems to me that for the following ...
0
votes
1answer
49 views

Electric Field and Neutral Objects

Due to electrostatic induction, when a charged object gets closer to a neutral object, sides of the neutral object can get charged. Thus, a charged object can attract a neutral object. However, is ...
0
votes
0answers
27 views

Is there a method to detect a magnetic field within this range: 100 fT to 1 pT

Is there a method to detect a magnetic field within this range: 100 fT to 1 pT (human brain magnetic field) I know there are SQUID magnetometers currently using in primarily Medical Researches. But ...
2
votes
1answer
33 views

Voltmeters and changing magnetic fields

A changing magnetic field pierces the interior of a circuit containing three identical resistors. Two voltmeters are connected to the same points, as shown. V1 reads 1 mV. What does V2 read? ...
7
votes
4answers
5k views

Can you make ice red hot?

This video clip allegedly shows an otherwise unspecified ice cube that turns red hot (and burns) due to induction heating. Can somebody explain how this works?
1
vote
1answer
78 views

Motional emf with rod

We know that $\mathcal{E} = -N \frac{\mathrm{d}\phi}{\mathrm{d}t}$. When we have a rod such as the one on the left moving through a constant magnetic field, how is it the case that the flux is ...
1
vote
1answer
67 views

Shouldn't the currents be time-continuous here?

My intuition is that the current upon an inductor (say, a solenoid) will always be time-continuous, without "sudden changes". But below is a case that seemingly contradicts this point of view. There ...