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 ...

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41 views

How many coils should I wrap my 4inch long solenoid with?

I am making a solenoid as a project... but I am not sure how many coils I should wrap it with. I am using copper wire, it is 32 AWG. I have tryed wrapping it with 100 coils, but I found that it's not ...
0
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2answers
53 views

Will this structure emit EM waves when excited by out-of-plane time varying magnetic field?

Say I create a structure from copper that looks like the figure shown below. It's an open circle whose ends terminate in protruding wires of length x. If I excite this with an out-of plane time ...
0
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2answers
74 views

Increasing efficiency of a kinetic energy battery charger

I want to use Faradays law to convert the kinetic energy from actions such as a jog/shake to produce electricity to ultimately charge a battery. Materials Neodynium Magnet 3/4 diameter (2) ...
0
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0answers
24 views

How detect activation loop from AMB / Mylaps transponder

I have a kart track with AMB transponder TRANX 140 and TRANX 3 decoder, That transponders has a small battery with 5 years duration, so i guess they are activated by loop just few millisecons and ...
0
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2answers
58 views

Ways to use electromagnets to pick up metal shavings at a distance

I work at a rotor machining plant and there is an issue for shutting a line down to clean up metal shavings, causes too much down time. I was thinking of using a strong electromagnet to have a "pick ...
0
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1answer
53 views

Propagation across a surface

How do stud sensors actually sense current, what would cause the effect to propagate across an 8x8 foot surface area and remain strong enough to be detected? I asked another group "what is ...
0
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1answer
32 views

Formula for electromagnet strength parallel, outside the coil

I am working on a electromagnet project to collect metal shavings off the floor after machining. I have a formula for the magnetic strength at a distance from the ends, but not parallel to the coil. ...
0
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2answers
30 views

Can we make a simple wireless device by mutual induction phenomenon

I want to make a simple wireless device (radio?) that consists of only two copper coils where changing magnetic flux in primary coil causes a current flow in the secondary. I tried, once, with LEDs ...
0
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1answer
66 views

Magnetic switch with no moving parts

Is there a magnetic switch (like a reed switch) but with no moving parts? I need a switch that can be turned on by a magnetic field but won't move around due to tremendous shock absorption.
0
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2answers
54 views

Reactive Power in Inductor and Capacitor

Suppose a RLC circuit with AC source. Why the net reactive power in the circuit is the difference of reactive power in the inductor and the reactive power in the capacitor ? As both of them store ...
0
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0answers
44 views

There is thermochromic pigment. Is there a magnetic variety of pigment?

I can mix thermochromic pigment with transparent epoxy resin into a brightly colored paste which changes colors when it detects a temperature threshold in the surface it is applied to. Is it ...
1
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3answers
100 views

Complex impedance of a transformer

I consider only an ideal transformer here (no leakage etc.). Let L1 and L2 be the induction coefficients of the primary and secondary resp., and M be the mutual induction coefficient. Assume that the ...
1
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3answers
105 views

Reactive Power in the circuit

Why is inductive reactive power considered positive while capacitive reactive power is considered negative in the circuit ? Both inductor and capacitor consume apparent power so I guess ...
0
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3answers
67 views

Make an electromagnet attract and repulse

I bought and electromagnet online hoping to make it attract and repulse metals changing the polarity of the voltage on it, but I ended up experiencing attraction all the time. Is there any way to ...
0
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1answer
66 views

What method do wireless routers use to break apart the received wave into different frequencies?

What method do wireless routers use to break apart the received wave into different frequencies ? Does it have anything to do with Fourier Transformations ?
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1answer
67 views

ionizing body with tesla coil?

I have made a tesla coil.Now I want to ionize my body with it so that I can give shock to people with my hands.Is it possible to shock someone with it?
0
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1answer
46 views

Welding Transformers?

I was thinking of making a carry handle for two microwave oven transformers in series, and also so that they can share a common ground without having to split the ground wire. I thought about bolting ...
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1answer
54 views

What are the options for short range under six inches 3D multi point location tracking?

What methods exist to track the position of points relative to each other. Particularly what methods allow the determination of the distance between up to ten points at once. The distance ...
1
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0answers
25 views

Torque and Current Frequency Relationship in Lorentz force

Lorentz force equation shows us that current is proportional to the force. Is it safe to assume that the force generated by an AC current at 60Hz will always have the same frequency? In other words, ...
1
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3answers
51 views

Hall effect device for circa 1 tesla gaussmeter

I'm thinking about building an unsophisticated bench instrument for measuring magnetic field density, just to support my learning about electromagnetism and building magnetics for power electronics ...
2
votes
1answer
38 views

What is vector potential in magnetic field?

The vector potential in magnetic field (represented by A), what does that physically mean? I have serious problem in understanding it intuitively. $$\nabla^2\text{A} = -\mu_0 \text{j}$$ I read that ...
0
votes
1answer
41 views

Magnetic attraction/repulsion with motor/generator and similar systems?

With generators and motors, is there a form of magnetic attraction or repulsion between the conductive element(rotor/solenoid) and the magnet's magnetic fields? If so, what formula would be best to ...
1
vote
1answer
40 views

Interpretation of radiation resistance in receiving mode

Assume we have an antenna in receiving mode, connected to a matched load. The equivalent circuit is a voltage source in series with the antenna feedpoint impedance and the load impedance. As we know, ...
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votes
2answers
64 views

How electromagnetic waves works, how they are created and how thay transform to electric signal? [closed]

Few days I am trying to learn more about electromagnetic waves, induction, electromagnetic spectrum... And how it's connected. Here is what I understand now: There is a lot of electromagnetic waves ...
2
votes
2answers
48 views

Moving the magnetic field around a fixed conductor?

From this figure: And many others related to electromagnetic induction, the main component of motion would be the conductor perpendicular to a magnetic field. I know it's possible to have it the ...
0
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0answers
22 views

Change in induced EMF due to change in wire connection?

A copper slab moving inside a magnetic field: I can calculate the induced EMF(vBL) and given the resistance of the load, can calculate the current. However, I'm curious with how the ...
0
votes
1answer
280 views

smallest possible length of copper wire, where I can measure capacitance via multimeter

I am a new highschool physics instructor and I want to show to my students the basic concept inside capacitors and how they work. I plan on showing them 2 simple copper wires side by side , ...
0
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1answer
61 views

Calculating a compass angle?

I am getting data from compass( hmC5883L) and trying to detect angle. Well, i dont really care about offsets, i just want to check that if its flat on the table ...
0
votes
2answers
46 views

Magnetometer- there is no low current feature?

I have gone over all magnetometers available, most of them using I2C, and connected to some MCU, and i couldn't find even one with interrupt. That means the processor cant go to sleep, and always has ...
0
votes
0answers
43 views

Three Phase Permanent Magnet Rotor Generator Magnetization

I have a three phase permanent magnet rotor synchronous generator. The rotor was recently removed from the machine in order to repair the shaft. The motor when when run at the same speed does not ...
2
votes
2answers
61 views

“window utilization”

I would like an explanation of the importance of window utilization in transformer design. I understand that it is the ratio of area occupied by windings to total area available for windings on the ...
0
votes
1answer
44 views

reflected electric and magnetic fields component

The question states that the direction of propagation of E is +x and +z plane. The goal here is to find the reflected component of E and H. I know that the propagation changes sign once it hits the ...
0
votes
1answer
47 views

Perpendicular (TE) polarization

Perpendicular (TE) polarization occurs when the electric field is perpendicular to the plane of incidence. I am having a hard time visualizing why that is the case in the following example. please let ...
0
votes
1answer
48 views

Detecting mobile phone in airplane mode

I am working on a project to detect mobile phones in a room to avoid cheating. But the airplane mode ha posed a problem. A google search told that all radiations are switched off during airplane mode. ...
1
vote
2answers
64 views

Component bodies physically touching

Is it ok when components touch each other (with body, not leads) after assembly? I know that resistors should be ok, but how about capacitors? Is it ok when I assemble them densely? Will there be any ...
0
votes
2answers
50 views

How to choose an electromagnet controlled by sound signal

I've asked here before but I was told to be more specific so here I go. I would like to build an electromagnet that I can control with sound input, more or less like a speaker but safe and powerfull ...
1
vote
4answers
198 views

Tape recorder head has only 2 pins, which one is for grounding?

I am trying to make my own cassette adapter that will help me play my music on my iPod through my car stereo system that supports only cassettes. For that I've bought a 3.5mm earphone jack and a ...
1
vote
1answer
48 views

Ionic Reflection [duplicate]

I finally went and got my Ham Radio licence. I've been reading about how radio operators use the ionosphere for long distance communication through ionic reflections of transmitted/received EM waves. ...
0
votes
1answer
41 views

Semiconductor Condution

I've read that semiconductors (i.g. intrinsic silicon) behave as insulators at absolute zero (since all valance electrons are shared via neighboring atoms). My question is, does conduction still take ...
0
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0answers
45 views

Simulating input impedance of rectifier with known power

I am simulating a rectenna with a dipole antenna and a bridge rectifier in ADS. As a diode's impedance is dependent on the current, to accurately measure the input impedance of the rectifier, I want ...
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votes
1answer
67 views

How to design ESD and EMI -safe circuits? [closed]

First of all, sorry if this question is too low level or stupid, but I really wonder how to design ESD and EMI(electromagnetic interference) -safe circuits. I have read the user manual of my FPGA ...
1
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0answers
84 views

Impedance discontinuity problem at transmission line?

I am confused about how the waveform will be to the left of discontinuity. Please help me understand it better. Here is my understanding: When the unit step hits the inductive discontinuity, at ...
1
vote
1answer
47 views

What is the optimal disposition of coil to maximize the magnetic field created?

I am trying to create a powerful magnetic field using coil, and possibly some ferromagnetic metal bars. The white box with the X on it, is empty, or made of air. Saying that I have no limits on ...
2
votes
1answer
56 views

E and H relationship

Can any one explain why the direction of H is -Z and +Y ? once I do the cross product and multiply it by -100 , I get -Z and -Y as directions.
5
votes
0answers
110 views

Winding method for barrel wound secondary center-taped EE core

I'm designing a high-frequency transformer, EE type core, with one primary, and a center tapped secondary. As the secondary current is relatively high and the window area is small, I will use copper ...
0
votes
2answers
51 views

electromagnetism

I came across this problem, and I am having a difficult time to understand the direction of E. why the final answer is in -z and y direction?, when I do the cross product I get -z and -y direction. I ...
0
votes
0answers
37 views

What is the half wave dipole antenna impedance when it is in near-field radiative region

We know that the half wave dipole antenna impedance is 73 ohms when it's in far field region. I am trying to find its impedance when it is in near field radiative region at lambda/2 distance from a ...
1
vote
1answer
70 views

Is a Wifi antenna both a transmitter and a receiver?

I only have one antenna on my Wifi card so I am assuming it is both the receiver and the transmitter, but I can't quite wrap my head around it. Does it constantly switch between being a receiver to ...
1
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3answers
107 views

Quarter wavelength antennas

I'm interested in learning how antennas work and why they are required to be a particular length in order to receive/transmit. I've learned that the length is choose to be a quarter wavelength of the ...
0
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2answers
73 views

Signal speed through different materials

I've been tolled that signals are carried by electromagnetic waves caused by oscillating charges, and that this action occurs in a manner similar to how billiard balls interact with one another. I'm ...