Questions tagged [electromagnetic-induction]

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Is induced EMF proportional to the square of the number of turns of a solenoid?

In order for this question to be clear I must first give some context: Consider a 10cm long solenoid (solenoid A) of radius approximately 1cm with 400 turns. Let the current in $A$, $I_A$, ...
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3answers
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Voltage vs. EMF for a varying magnetic flux against an ohmic circuit

Suppose there is a circular wire, whose material is ohmic with uniform resistivity. If an increasing magnetic flux is applied to this "circuit", electric current will flow in one direction. Then by ...
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6answers
397 views

Right Hand Rule?

I'm trying to determine what the correct right hand rule is, but Google isn't helping. I've seen three different versions of Fleming's Right Hand Rule now, and I'm very confused. Here are three ...
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1answer
62 views

Usefulness of an iron core in a magnetic coil used to generate current

I wish to light a LED by moving a permanent magnet relative to an inductor consisting of a coil of copper wire. Can I increase efficiency (current produced for a given magnet motion) by using an iron ...
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1answer
86 views

How a moving electron gets deflected in a magnetic field in on direction and the positron gets deflected in the opposite direction? [duplicate]

In a question Why does nature prefer the right-hand rule over the left-hand rule? was another question My question is, why this direction and not the opposite? This part of the post received no ...
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1answer
50 views

The effect of the resistance of coils on DC motor

I have some doubts on how the resistance of coil affects the efficiency of a DC motor. I assume there are two DC motors operating under the same supplied voltage, and the resistance of the coil $R_1$ ...
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3answers
47 views

What happens when a super large charge is brought close to a conductor with limited supply of charges?

Imagine the following induction scenario: a super large charge +Q is brought close to a real conductor with limited supply of charges; that is, the total charge of all electrons inside this conductor ...
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3answers
367 views

Can Kirchhoff's Voltage Law be applied here?

First, consider a simple circuit comprising of an ideal battery of EMF: E and a single resistor of resistance R. Imagine that the switch is opened in the circuit. In the battery, some internal ...
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1answer
217 views

Emf in ac generator

I know that emf induced in ac generator equals [N.B.A.w.sin(wt)] And i noticed that the negative sign of lenz rule disappeared. Does this mean that emf will not oppose the change in magnetic flux?
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3answers
290 views

Direction of Hall current

A Hall current arises when electric currents transverse to a magnetic field exist. In this figure (found online), the Faraday current appears to be going upwards due to a magnetic field pointing into ...
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2answers
128 views

Which provides the energy for induced current at the starting moment of the lenz's law

I am learning about magnetic fields, but I get confused with the way energy is transmitted in Lenz's law. As I read on the question Explaining Lenz's Law without conservation of energy: Let's ...
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2answers
53 views

Why does a voltage appears between $A$ and $C$ when this coil is rotated?

Find the voltage between the points $A$ and $C$ when a wire is conecting $A$ and $D$. We know that there is a magnetic field $B$ perpendicular and entering in the papers plane, the semicircular metal ...
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1answer
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Current in circuit after joining two inductors with different currents through them [duplicate]

Let's take two inductors: one has its peak current (say, Io) flowing through itself and the other has no current through itself. Now if these two inductors are joined in series in a closed circuit, ...
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1answer
60 views

Measurement coil for magnetic fields, linearity and frequency of the field

I am trying to measure an oscillating magnetic field, of a solenoid and in the air gap of a transformer core. I have a Hall effect sensor, but its frequency range is limited, so I have put together a ...
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4answers
147 views

Is alternating current or alternating voltage supplied in the primary coil in a transformer?

In an ideal transformer, I want to know whether a alternating current or alternating voltage is supplied in the primary coil. If AC current is supplied, then there is change in magnetic flux and an ...
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2answers
186 views

Time varying magnetic field and faradays law of induction

According to faraday's law we say that , whenever a magnetic field varies with time it creates an "electric field" . But I do not understand , how can a time varying magnetic field produce electric ...
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2answers
61 views

Is it right to say that magnetic field energy is created only by non-conservative electric field?

In all the examples of generation or existence of Magnetic Field energy I have seen so far, I couldn't find any example, where magnetic field energy is created without Non Conservative Electric field, ...
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3answers
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Where does the Magnetic Field Energy come from, in case of a charged particle moving with constant velocity?

A charged particle moving with constant velocity creates Magnetic Field around it. If there is Magnetic Field, then there must be Magnetic Field Energy. The question is, where does the Magnetic Field ...
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4answers
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What do we mean by magnetic field energy? Does this magnetic field energy in a current carrying wire comes from the battery the wire is connected to?

Let me take an example to elaborate my question. Suppose we have a simple circuit with a battery (E) and a resistance (R). Current will be flowing in the circuit, I = E/R. Now, we know that that if ...
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1answer
62 views

Faraday's law superconducting [duplicate]

When we say flux can't be changed through superconducting coil , because resistance is zero , So this implies there is no induced emf in the coil , If it is so what makes current flow in the coil ...
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1answer
55 views

Magnetic fields for communication or remote interaction with devices [closed]

My understanding is that the electric fields are primarily what is used in communication technology and what most antenna design based around. And I am aware of loop antennas that act as an induction ...
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1answer
184 views

Magnitude of induced Electric field

Let us suppose there is a uniform magnetic field present in all space, pointed into the screen. If this magnetic field varies with time, Electric fields will be produced that in turn produce fields ...
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1answer
37 views

Interaction between a current-driven coil and a second passive coil in the same space

Good evening,I have some doubts about mutual inductance. I hope that somebody will be willing to reply to my questions. We have a coil L1 traversed by a current I1. If the current is stationary, L1 ...
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2answers
45 views

Physical significance of calculating inductance?

Consider a simple situation: Of an infinite wire and a loop kept in front of it. We are to find the mutual inductance of the system. $\phi = Mi$, where M denotes mutual inductance. The method we ...
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3answers
51 views

Why does a varying magnetic field exerts force on a charged particle?

I know that the equation is force=charge*velocity(perpendicular component)*B. But this equation is just for calculating the force. My question is why would even a charged particle experience force on ...
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3answers
113 views

Self induced EMF in DC

Why is self induced emf much greater than the source voltage in a DC supply when the switch is opened?
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0answers
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How to calculate the total emf and current in a secondary winding composed of multiple materials

In transformers, flux swings in the primary winding induce an emf in the secondary. Typically the secondary is taken to be a single material, but if it is instead taken to consist of multiple ...
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Why is magnetic flux proportional to the current?

I know this answer, but it does not answer my question. I want to know why is this proportionality, where does it come from. How can I derive it? To put it differently, I want to know where the $$U=L\...
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1answer
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Using superconducting coils as a transformer

In experiments such as tokamaks, typically an ohmic transformer (primary) is used to produce current in the plasma (secondary) by swinging from to the most positive to negative magnetic field. Ideally ...
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2answers
101 views

Difference between induced emf in a loop and a wire

In the given figure, I was asked to calculate induced emf in the loop and individual wires of the triangle. I have a doubt that when I am calculating the emf of the whole loop, between which two ...
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5answers
169 views

Inductor in A.C. Circuit

I am reading about inductors connected in A.C. Circuits. I understand mathematically that the current lags behind voltage. But what is the physical explanation for this? My understanding: As the emf ...
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1answer
120 views

Superposition of Magnetic fields in a Transformer

Lets say we have a transformer with two primary coils. The coils are positioned end to end such that unlike poles are adjacent (NS or SN). The current in one of the coils has a phase shift of 90 ...
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2answers
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Does the magnetic field line passing along the axis of a bar magnet ever reaches to South Pole?

Consider a bar magnet, and the magnetic field line that goes through its axis and through the center of its north pole and thus follows a straight line path out of the magnet. Will this line ever be ...
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1answer
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Magnetic field inside conductor and linearity of eddy currents

Eddy currents are currents that are generated in a conductor to produce magnetic fields that oppose the magnetic field originally produced by current flowing in the conductor. The figure below (from ...
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1answer
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eddy currents to heat reinforcing steel

The latest cook tops heat iron pans using high frequency circuits. IS it possible to do this with construction reinforcing steel also known as rebar) used in concrete slabs? I put rebar on a cook top ...
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1answer
68 views

Will a pulsating electron beam passing through a copper pipe induce eddy currents within the copper pipe?

If a pulsating electron beam is beamed down the center of a copper pipe, so as to not make any physical contact with the pipe, the beam should create a pulsating magnetic field that will not change in ...
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1answer
52 views

Electromagnetic induction and magnetic field (conducting rail problem)

Since we know the work done by a magnetic field is zero.now how does the magnetic field changes the kinetic energy of rod when it applies force BIL (where I is current at any instant) moreover if we ...
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0answers
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Why do both these molten metals round in a crucible?

In one of my classes this past semester, we did a casting lab. In this lab we used an induction furnace which uses a coil to generate heat within the material. One of the things that I noticed, was ...
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3answers
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Self Induction and Inductance [closed]

A coil with zero resistance has its ends labeled a and b. The potential at a is higher than at b. Which of the following could be consistent with this situation? Mark all that apply a. The current ...
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1answer
56 views

Can I induce AC current with a straight piece of wire and a spinning magnet?

The idea is, I have a fast spinning magnet and next to it a wire (with 2 free ends). When the + pole is next to the wire it will attract the electrons, and when the - pole is by the wire it will ...
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1answer
455 views

Magnetic Flux conservation

My teacher said that after switch is shifted (after very long time), $\phi_i = \phi_f$ $\implies i_oL = i3L \implies i = \dfrac{i_o}{3} $ where $i_o$ is $\dfrac{\varepsilon}{R}$ So the initial ...
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Faraday's law. And Faraday's law of induction

Can anyone properly tell me the difference between the two, and which one historically came first. A majority of sources directly connect "emf" to flux but the 'flux rule' isn't absolute. It isn't ...