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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2
votes
1answer
40 views

Electromagnet for string vibration

I recently read a lot about guitar sustainers, for those who don't know what are they - it is basically an electromagnet with an amplifier. It takes an input from pickup, amplifies it and then ...
-1
votes
1answer
45 views

Feeling strong “static electricity” on external harddisk USB cable? [closed]

Whenever I connect my Seagate 2TB external harddisk to the power through its original transformer, I can feel something special at metal connector of the USB cable (which is used to connect to the ...
0
votes
0answers
62 views

What is the ideal shape for rail-gun?

I was trying to create a low voltage (30V) rail-gun. I have quite a hard source of power that doesn't drop voltage upon current drain, further more, this source is re-inforced by big Tesla capacitors. ...
0
votes
1answer
54 views

How to get an object charged?

I want to create electrostatic force between two isolated objects which are 3 meters apart from each other. The electrostatic force should be very noticeable, so I want to get the objects charged ...
7
votes
1answer
262 views

How does this iPhone app measure the power flowing through an AC appliance cord?

My electric utility released an iPhone app called "DTE Insight" which (among other things) measures the amount of power flowing through an appliance's power cord by asking you to hold the cord against ...
0
votes
0answers
49 views

How would I make a controllable multi point magnetic surface?

Immagine that you have a thin plate, a metall ball on the plate, and a permanent magnet beneath the plate. This means that the balls xy coordinates is the same as the magnets. So the ball follow the ...
0
votes
1answer
60 views

Why does the speed of the Electromagnetic wave in the material depend on the frequency of the wave where as they are constant in vacuum (freespace)?

I am confused on why would the propagation speed of any EM waves at ANY frequency is constant in the free space (vacuum) but they seem to disperse in any other materials as the propagation speed of EM ...
1
vote
1answer
54 views

Can a solenoid have its magnetic field “focused”?

Imagine a solenoid generating a magnetic field. Can this field be focused so that it exists only in a certain section of that solenoid at a given time. If a typical solenoid looked like: ...
0
votes
2answers
49 views

Help with a ring launcher

I'm not sure if this is the right place to be asking this question, so close it if it's not, but I need help on a physics project. My current project is a ring launcher (Elihu Thomson Apparatus). I ...
2
votes
3answers
117 views

Is Back EMF relevant in dynamos, where there is electric generation?

While doing some research about dynamos, I came across a situation wherein there was a question about the validity of my dynamo design. The counter to the design I suggested was that there would be ...
0
votes
2answers
145 views

A cubical LC circuit

I would like to solve for currents through inductors and the voltage across capacitances of the attached circuit. I am trying to figure out a correct method to solve such circuits which could have the ...
0
votes
0answers
56 views

2mm linear actuator (electromagnet, hydraulic, etc.)

I am currently trying to make an idea become a reality, but I do not have a background in the electrical engineering, I am in fact a Software engineer. I have been searching a lot for a 2mm x 2mm x ...
-1
votes
2answers
59 views

What are evanescent fields?

I am not able to understand what is the origin of the evanescent field, how do they interact and what is the physics behind it.
1
vote
2answers
68 views

How does the shape of the coil relate to the magnetic field around it?

I want to know if the shape of the coil affects the path of the magnetic fields around it. The two different shapes that I have are Helical coil and a spiral coil (in a plane).
0
votes
1answer
105 views

How to make a simulation for wireless power transfer circuit in HFSS (High Frequency Structural Simulator) software?

I want to simulate a circuit of wireless power transfer consisting of two resonating coils along with a loop with each coil. I am stuck with introducing a coil in HFSS.
0
votes
2answers
45 views

Is there any simulation software that can be used for simulation circuits of wireless power transfer?

I am searching for a simulation software that also shows the interaction between electromagnetic waves in a wireless power transfer setup.
0
votes
1answer
62 views

Can magnets break LED notification light on phone? [closed]

I'm posting this question here because it's about magnets and electronics. Please tell me if it's better suited to another site! I've been messing around with some reasonably strong magnets around my ...
1
vote
2answers
71 views

How to make an effective electromagnet?

I am making a speaker with some neodymium magnets and about 3m of copper (insulated) cable. How would I configure this to make it loudest/best electromagnet?
1
vote
0answers
52 views

Electromagnetic interference in a Car

I am currently working with a 12 volt inverter to power EL tape. The tape is wired in various places in my vehicle, I have tested it in my car and I hear a high pitched noise on my radio when I try to ...
2
votes
6answers
735 views

How to create an electronically controllable resistance to a physical movement?

What is the best way to create an electronically controllable resistance to a physical movement? For example, at the gym you control the resistance to movement by putting more load, more weight. Is ...
1
vote
1answer
83 views

Rigging an MRI machine with club speakers and lights

I'm using a magnetic resonance imaging (MRI) machine to fMRI trial subjects while they experience club-like conditions. This means I need loud, high-fidelity speakers, flashing multicolored lights ...
1
vote
1answer
53 views

Meaning of “grounded” in a uniform field

I am reading an example in a book which considers a grounded conductor inside a uniform electric field. The author stated that "grounded" means, as usual, \$V=0\$. But I am confused. In my opinion, ...
3
votes
3answers
370 views

Please correct my understanding of “how electric works”

Being in Information Tech, I'm good with programming languages, processor logic, and the such. It's only natural I got curious about that outlet I plug my servers into. Here is where I am: I tried ...
1
vote
2answers
119 views

Loop count in a current transformer

I was reading this article about current transformers. It says that, the loop count is 1 when the wire is just passing through the core. And there are 2 loops when it is wound for once, and 3 loops ...
0
votes
2answers
116 views

Stepper motor failing. Electrical interference?

Update: This question is already so long, I'm hesitant to add to it but it occurs to me to ask if electrical interference between the stepper motor wires could cause this sort of behavior (motor ...
-4
votes
1answer
60 views

Good book/reference for electromagnetism and distributed elements model

I am looking for a good explanation of what is in "between" of Maxwell's equations and the lumped model. I am talking specifically of RF electronics and the distributed elements model. I am ...
0
votes
0answers
20 views

Infer the EMF amplitude of a generator from limited motor-mode data

Context: I am designing a very low speed alternator for small power devices, and I would like to select the correct motor for my application. The problem is, the cheap ones provide very little data - ...
2
votes
0answers
56 views

Generate magnetic field from card stripe wav or text data [closed]

Internet has a couple of answers about reading and decoding card magnetic stripe. I have another question -- how can I create magnetic field from stored stripe data? I want to take the data that I've ...
1
vote
4answers
239 views

How can I make a fine tipped object emit an electric field similar to that of a human finger?

I've asked this before, but knew less about the tech and didn't word the question properly. I know other people have asked similar questions and knew little, so let me be as specific as possible here: ...
1
vote
1answer
105 views

Help building electric generator? [closed]

I am in the process of building an electric generator for the first time, and I have found out most of what I need to do, except the following things. Can I have 2 rows of magnets linked together ...
0
votes
1answer
53 views

Question about magnetic field induction and AC generator

Since electromagnetic induction (faraday's law) is described as inducing a current why then would you need to be grounded to receive an electric shock? Since current is already present? If say (use ...
0
votes
1answer
81 views

DC 5 Volts - 2100mAh Electric Motor Generator. How?

I have spent my entire weekend trying to locate a place where I can buy a 5 Volts - 2100mAh Electric Motor/Generator. My goal is to spin this motor up to a certain RPM to generate the 5 volts and ...
19
votes
3answers
1k views

Why isn't there a potential difference across a disconnected diode?

I know this question sounds silly, as if there was a potential difference a current would be created when the terminals are connected together and this would mean energy has come from somewhere. The ...
2
votes
1answer
99 views

Increasing the surface area of an electro magnet

I am trying to design an electro magnet with a large surface area at the end. The first design used a 1/4" rod wound with magnet wire resulting in about 10 ohms of resistance driven with 12 V. This ...
0
votes
0answers
56 views

Minimum AC voltage that causes nerve damage?

What is the minimum AC(50-60Hz) voltage that can do harm/nerve damage? I know that a few hundred volts (even 100?) has been documented to cause nerve damage that resembles a crush injury. I also know ...
0
votes
1answer
170 views

How to design a magnetic vibrator?

I plan to create a magnetic vibrator to shake a small container. What I plan is to buy Two "Magnet Wire 14 AWG Gauge Enameled Copper 1.5lb 118ft 200C Magnetic Coil Winding" a custom made container ...
0
votes
0answers
48 views

Use Earth and Ground Rods as Tip and Ring for a Modem

My co-worker and I recently tested this theory out with two Cermetek 1794A modems. Datasheet: http://www.cermetek.com/Catalog/High-Speed-Modems/DataSheet/CH1794A_607-0020.pdf Now first, we did two ...
1
vote
2answers
60 views

electromagnet question

I have an electro magnet(just nail and wire). I linked the nail/wire to 1.5 AA battery, nothing. 9V and 12V, nothing. I then linked the nail/wire to a 6V lantern battery and it pickup up the ...
0
votes
0answers
46 views

Theoretical question about electromagnetism - Uniqueness Theorem for the free space

Given the Maxwell's equations, the sources of a field and its boundary conditions, the solution found is unique, as stated by the uniqueness theorem. In the frequency domain, if the considered region ...
5
votes
4answers
397 views

Concept of 'frequency' in wire vs electromagnetic frequency in fibre optic cable

I am having trouble understanding the concept of 'frequency' of a signal in an electrical sense in a wire vs the concept of 'frequency' in the electromagnetic sense in a fibre optic cable. Are these ...
-2
votes
2answers
103 views

Is a bus bar needed?

For a short period of time, 10 kA must flow in a circuit, is a bus bar needed? I mean, since the flow of current duration is less than 0.010 seconds on a certain wire?
1
vote
1answer
38 views

EMF in an Open Circuit?

Lets assume we have a wire passing a magnetic field, it is know that EMF is induced due to the magnetic field, what if the wire is not connected to a circuit what happens? Is there ay voltage in the ...
-1
votes
2answers
72 views

If resistance is very high?

$$ V = IR $$ If there is a conductor with very low resistance, moving in a magnetic field, will it induce low EMF = IR? And a high current? Im confused at that point... Lets assume a conductor ...
1
vote
3answers
81 views

How to detect non magnetic material?

I want to design a paintball counter. I have a metallic or plastic tube through which a paint ball passes. How can I detect that the ball passed? What kind of sensors do I need? I cannot see the ...
2
votes
3answers
448 views

My DIY solenoid does not work

DESCRIPTION: Hi there, I don't know lot about electricity and I`m having problems with my first solenoid-prototype, I tried to build it watching you tube videos. I have attached the pictures of the ...
1
vote
1answer
76 views

When -EMF is induced can we keep current the same?

I'm confused at how Back EMF or (-V, -EMF) reduces current, and conserving the overall power. Let use the following simple example to help my understanding: A solenoid produces a magnetic field B, it ...
0
votes
0answers
31 views

How can simulation be fast when Electric Field is being measured with probe in CST Microwave Studio?

I am measuring the electric field in the closure box with aperture and using probe to achieve that. But I have a problem. When I use the probe for measurement, results are not accurate in transient ...
1
vote
1answer
144 views

How internal capacitor stud finders work?

I don't understand how can a non magnetic object like wood be detected using a stud finder For instance, stud finders find wood from dielectric constance, but I don't understand the princible. The ...
0
votes
1answer
50 views

Electric flux density independent of bound charge?

The electric flux density is defined as $$\mathbf{D} = \epsilon_0 \mathbf{E} + \mathbf{P}$$ where P is the polarization vector of the material. As I understand it, the net electric field includes the ...
1
vote
3answers
124 views

Why is the magnetic field perpendicular to the magnetic force?

In the case of the electric field, we define the field as the force at each point in space exerted on a unit charge. This is intuitive, as the field will give me a good idea of how a charge will move ...