The kind of magic without which all of this wouldn't be possible. This tag should be used for questions about the **physics** of the fields that charged particles create and how these fields interact. It should not be used for all questions involving electromagnetism, that would be everything on ...

learn more… | top users | synonyms

0
votes
1answer
82 views
+50

How to calculate the induced voltage?

From the given diagram: Conductor(C) is the only movable part with given velocity (v), connected to a stationary terminals(top & bottom) and an exterior circuit with a load. Will current flow ...
0
votes
1answer
47 views

Making a magnetic levitation system with arduino

I am planning on making a magnetic levitation system with an arduino that checks the value of a hall's effect sensor twice per second (but I have tried even 1000 times a second though) and turns the ...
3
votes
2answers
61 views

How can current flow in dipole antennas when there is no potential across them?

I have been trying to understand antennas and I've been trying to analyze how the transmitter's energy is transferred. It is clear that for current to flow there must exist a potential difference ...
0
votes
2answers
67 views

Can a Magnet power a fan for a wind and electricity output?

can it really be possible to power a ceiling fan with the use of magnets and could give you a wind and electricity output? how to do it? (For Remote Areas Without Electricity).
-2
votes
1answer
44 views

Magnetic field of a current carrying conductor [on hold]

why magnetic field of a current carrying conductor is produced in the form of concentric circles and why doesnt magnetic field converge or diverge from the conductor carrying current. A metal is acts ...
-1
votes
0answers
33 views

How to calculate the induced voltage in this case?

Here is a picture of the situation I don't know the details. Now what do I mean by details? Well, for example the strength of the bar magnet, how many loops the coil contains, etc. But I know that ...
1
vote
0answers
63 views

Building an electromagnet to work over an air gap

I am currently working on a project where I am building an electromagnet that works over an air gap. Specifically a gap of about 0.3 inches. The electromagnet type was selected because I need to be ...
2
votes
1answer
150 views

Power Supply Sees Electromagnet as a Short Circuit

I'm designing a circuit in which current periodically passes through a copper coil (with an air core), which acts as an electromagnet. The resultant magnetic field then repels a neodymium magnet ...
0
votes
0answers
24 views

Necessity of off-resonance operation of tightly coupled coils for maximum efficiency?

On Wireless Power Consortium webpage there is an article about Magnetic Resonance. These paragraphs in the page surprised me (emphasis is mine): You might expect that operating tightly coupled ...
-2
votes
1answer
117 views

influence of device upon another device from power supply [closed]

Suppose I have a power supply like an ATX computer power supply (which outputs a pretty stable voltage). Now, assume that I an a friend both connect some electronic devices (in parallel) to this power ...
3
votes
2answers
893 views

Skin depth at 50 Hz is much longer than the thickness of the shield of a coax cable. Then how does it work?

The title already narrates the question. We know that using a coax cable for audio amplifier input remarkably reduces 50 Hz noise. However the skin depth of the EM radiation at 50 Hz for copper is ...
0
votes
1answer
67 views

Solenoid circuit current issue

I have been working on a circuit go make a solenoid switch polarity with arduino. I originally used transistors (NPN) rated for 1A and 625mW in between the ends of the solenoid and ground. These all ...
0
votes
1answer
48 views

What is the difference between a magnetized nail and a coil?

When I was a child, I brought a nail (metal bar) and I made some turns around the nail. It was something like a coil and the nail was the core of that coil. When I applied DC on the coil using 1.5 V ...
-1
votes
3answers
89 views

Magnetic Field vs E-M Field

I have got some questions on this topic based on the best answers I get to these: -1- If magnetic fields arise due to electric currents in conductors, we say they are not E-M waves in nature; it is ...
0
votes
1answer
70 views

Why is there a copper winding isolated from the iron core of my transformer?

Here is a picture of a 1970's arc welding station. There is a 9 inch bar of metal surrounded by 88 windings of 4mm copper, that used to be on the end of the secondary winding, which is made up of ...
0
votes
1answer
44 views

magnetic flux cut by a magnet

I have two magnets A and B: Magnet A is movable, Magnet B is fixed. Magnet A is smaller and weaker (surface area of 1 Square cm) , where as magnet B is stronger and bigger (surface area of 4 Square ...
0
votes
1answer
30 views

What happens when I put a charge inside a conductor that is already in static equilibrium?

I understand how, when a neutral conductor is charged, the charges will repel each other and after the relaxation time will all be distributed in the surface of the conductor. My question is: after ...
0
votes
1answer
53 views

(theoretical) doubt in Gauss law [closed]

Let us assume the universe is filled with positive charges. At a particular point, all the positive charged particles will be symmetrical. Now, we assume a sphere of radius r (finite) as our Gaussian ...
1
vote
1answer
38 views

Clamp Meter Working Principle

Basic theory of clamp meter to measure rms of current wave. What I have in mind is that wire creates the changing flux that induces voltage in the meter.This voltage is calibrated ? Also how does the ...
0
votes
0answers
27 views

Generating current from a high voltage power line [duplicate]

I learnt that power lines carry high-voltage electric current with electric fields and a magnetic fields around them (That i just think go to waste). So i was asking, if i surrounded a single power ...
0
votes
2answers
50 views

Correct graph for induced E.M.F

Screen shot of the question is given below. What I know B field acting on the Ferris wheel is given below, And induced E.M.F initially is zero , therefore I can neglect answer number one and ...
1
vote
1answer
51 views

Findning the magnitude of the current

Screen shot of the question is given below. My thoughts Since the B field into the page is decreasing, and induced current is induced in such a way to oppose that condition. So here I can ...
-1
votes
2answers
33 views

How to determine the correct graph for induced current

To be straight , this is a home - work question . This is the question. Okay, now let me give you the my attempt and what I believe to be correct. Here E.M.F induced across OA is constant, ...
4
votes
1answer
75 views

How does a “neon tester” work?

I have seen the different answer posted in internet. Many people are saying glow of neon light on tester is due to stray capacitor formed by our body and ground. I am ok with that until I found ...
1
vote
2answers
198 views

How to choose the correct graph

This is a question based on electromagnetism. Screenshot of the question and all the necessary stuffs are given below, This is the figure , And the choices that are given, First choice ...
6
votes
1answer
141 views

Why does EM radiation travel much further than the magnetic field of an equivalent power electromagnet?

If both fall of as 1/r^2 from the source then why can radio waves travel around the world and still be picked up easily at the right frequency but the field from a powerful electromagnet can not?
0
votes
2answers
64 views

About induced current

This is a homework question that I have stuck for a while and couldn't able to come up with the correct answer. So here is the question, My thoughts towards this question When I move the rod PQ ...
0
votes
1answer
67 views

Direction of eddy current

To be honest, this is a homework question. Screenshot of it's given below. And the five choices are given below, What I already know I know that Eddy current is a circular electric which is ...
-1
votes
1answer
55 views

Confusing transformer winding, what is it and can i change it?

here are two 380V to 24V/48v transformers that weigh 10 pounds each. I was hoping i could get 15V with 500w out of one at 240V and measure the welding potential. the secondary winding uses 0.5mm ...
3
votes
1answer
67 views

A doubt on electromagnetic induction?

First of all I have to admit that this is a homework question. Screenshot of it is given below, I am able to find only two things, and they are given below : Magnetic force acting on each frame ...
0
votes
0answers
51 views

What do we mean when we say that a quantity is phase wrapped?

I have asked a question here in researchgate and I'm looking forward to get the answer. I thought it might be helpful to post the question here in an electrical engineering Q&A site. please inform ...
1
vote
1answer
34 views

Phase angle and amplitude -

A plane electromagnetic wave has the shape: \$\vec{E}(\vec{r},t)=E_0\cdot cos(\vec{k}\vec{r}-\omega t)\cdot \vec{e}_y\$ \$\vec{B}(\vec{r},t)=(B_1\cdot cos(\vec{k}\vec{r}-\omega ...
2
votes
3answers
107 views

Doubt on induced voltage

Honestly, this is a homework question. Below you could see the description of the question Here you have the relevant answer. My argument Here we can neglect answer number 1 and 4 Reason : ...
0
votes
5answers
167 views

Does a coiled wire have a higher resistance than straight wire?

If you take a straight piece of wire that is insulated and coil it around a non ferrous object like piece of wood would the resistance change?
1
vote
3answers
67 views

BLDC max speed KV or Hz?

So from what I've understood, the KV rating for a motor gives us the rotor speed based on the voltage applied at the phase of the motor. Having looked a bit deeper in ESC / inverters, I've come up ...
1
vote
0answers
29 views

Question about transformer reflected source

The following show the idea how a Thevenin equivalent source is used to replace the primary circuit of transformer. In textbook it is commonly stated that the load impedance sees an equivalent ...
-2
votes
2answers
88 views

Periodicity of sinewave

I am studying about continuous time periodic signal in that I saw some examples of sine waves and I have a question. The example is \$sin(400 \pi t)\$ is periodic or not. The explanation is given that ...
0
votes
1answer
34 views

units of magnetizing force

In electromagnetic field theory, we talk about "magnetizing force". Units of magnetizing force is A/m (Amperes per meter). It's obvious that units of force is Newton. So, is amperes per meter equal to ...
1
vote
2answers
94 views

How do we model the behaviour of circuits on ultrashort time scales (< ns)?

The electric field has a finite propagation speed. How do we describe the behaviour of circuits on timescales before even changes in the electric field have reached the entire circuit? Is this is a ...
0
votes
1answer
46 views

permittivity and conductivity vs. attenuation [closed]

Is there any direct relationship between permittivity of a medium and attenuation of an EM wave? What about conductivity vs attenuation? edit: Ok for instance an EM wave traveling in sea water. I ...
-1
votes
1answer
54 views

What is a safe level of electromagnetic radiation measured in terms of received signal strength indicator (RSSI) e.g. -26 dBm?

We know that the laws of our countries set the regulatory limits of EM radiated power based on the EIRP transmit power of the antennas of devices. However, the received incident power is more ...
0
votes
1answer
62 views

Does circular motion of electron perpendicular to the magnetic field experiences a force?

If i am moving a charged particle in a circular motion and then applying the magnetic field perpendicular to this circular motion ,will the charge experience a force. Note that magnetic line produced ...
1
vote
2answers
61 views

Capacitance of a single charged plate?

Lets say we have a single plate that has a charge of +Q on it. A plate with charge -Q is infinite distance away. Will the plate with +Q have a capacitance associated with it? Why or why not? I was ...
0
votes
1answer
49 views

Difference in Lorentz force?

From the following diagram: Lorentz force can be calculated from the following formula: F = IL×B What about this wire in the following diagram? Assuming that all the variables are the ...
1
vote
1answer
76 views

Advantages of parallel over serial connections

As far as my understanding goes, parallel data connections are faster than serial at the same frequency. However, when you increase the frequency in parallel you start getting bits 'cross-talking' and ...
0
votes
3answers
75 views

Capacitor and inductor power factor

I need an explanation about the leading and lagging power factor at electron level. Case1: In a inductor it has the lot of free electrons are ready to move when we applied a voltage(AC or DC). If we ...
0
votes
1answer
46 views

Electromagnetic or microwave cooling

Heat means stored kinetic energy in matter. Microwave owens and induction heaters works on increasing kinetic energy on matter. Is it possible to make inverse of this heaters like cooler. We can ...
3
votes
2answers
94 views

PCB coil electromagnet driver

Based on external sensor inputs, I want to vertically pulldown & release (in a controlled manner) a 7mm neodymium magnet enclosed inside a circular elastic diaphragm. I want to keep the size as ...
0
votes
1answer
75 views

What is the importance of EM field theory in electrical engineering? [closed]

I am a student of electronics and instrumentation engineering and have a course of electromagnetic field theory in our semester. Though haven't gone so deep in subject but have some primary idea about ...
0
votes
0answers
28 views

Do RFID-shielding wallets protect against all variants of RFID coupling (even magnetic)?

I have been thinking about getting some kind of RFID-shielding wallet or a set of sleeves for some of my credit cards. Now from what I have seen there are different types of RFID coupling in use, ...