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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2answers
132 views

Where does radiated power come from?

I've had electromagnetism classes back in uni, but I'm having a hard time linking them with that matter: Take a car antenna -which I assume is simply a wire, coiled or not-, and apply a voltage ...
0
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1answer
72 views

Two conductors in a magnetic field, canceling each other's EMF?

If two conductors are in a changing magnetic field, oriented the same in the field, and they induced equal EMF's, can their wiring be oriented in a way that they can cancel each other's induced EMF? ...
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0answers
34 views

where i can find solution manual to Foundations of Analog and Digital Electronic Circuits? [closed]

its link on amazon is http://www.amazon.com/Foundations-Electronic-Circuits-Kaufmann-Architecture/dp/1558607358/ i have google for hours and cannot find its solution manual, so where i can get its ...
0
votes
1answer
31 views

What material is comonly used as insulator in laminations?

I am trying to build a brushless motor for quadcopter use, with a semi-CNC lathe and a CNC mill. I know I can buy a stator core on gobrushless or maybe other place, but I want to know if I am able to ...
0
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1answer
33 views

Hall Effect and Magnetoresistors

As per my understanding, When an electric field is applied to a current carrying wire, it exerts Lorentz force on electrons and hence a transverse electric field is generated. Also when we apply ...
0
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1answer
51 views

Minimal Hall effect sensor circuit to keep something off after certain RPM achieved

I have a somewhat limited understanding of electronics and circuits. I'm trying to build a circuit that will keep a transistor in an off state after a given threshold of RPM is achieved using a A3144E ...
0
votes
1answer
57 views

Super fast magnetic field by an electromagnet?

Was wondering about the possibility of creating a magnetic field in milliseconds or less? I know it's possible based on certain labs achieving 60-100 Tesla and more. But what about creating a 2 - 5 ...
0
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2answers
83 views

Supercapacitors vs. High Voltage Capacitors with Inductive loads used in CoilGuns or Solenoids

I'm looking for some insight on whether an 1000 Farads at 2.7v or 5.5v would be more effective than say 10,000uF at 400v-450v when creating a strong magnetic coil. The intent is something similar to ...
1
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2answers
54 views

Magnet in the generator?

I'd like to know if there is some magnet in the rotor or in the stator of the generator? Or neither of those (rotor & stator) need a magnet for the current to flow?
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0answers
52 views

For the following circuit find the turns ratio of the ideal transformer

my solution is: power P = V^2/Z Z = sqrt(R^2+XL^2) Z = sqrt(2^2 +(2*3.14*1000*0.001) Z = 3.206 ohms so P = 2 Vrms^2/Z = 2 120/3206 = 74.85 watts Power P = V^2/Z V^2 = 74.85 * ...
1
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1answer
109 views

How to build an H-bridge using MOSFETs? [duplicate]

I want to reverse the polarity of my current source, which is a capacitor in this case, in the middle of discharging phase. Also the capacitor bank is being discharged through a coil to make a short ...
2
votes
1answer
46 views

How to calculate the Induced Voltage Given Spinning Conducting Loop? Intro to Electromagnetics problem

I'm having trouble figuring out a different variation of this problem. On my homework, I'm asked to find the induced EMF for the following B field: $$\vec{B}=50\vec{a_y}$$ I was able to figure out ...
1
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1answer
52 views

Magnet strength in dynamo design

I come from a computer background, and apologies if this question sounds elementary. While designing a dynamo, I came across a problem of how to calculate the the strength of the magnetic field, and ...
2
votes
1answer
95 views

What are the bare minimum parts needed to operate a magnetron?

I recently took apart a microwave, and I managed to get a magnetron out of it, as well as a transformer that appears to be the power source for the magnetron, but looks a little small for the ...
0
votes
0answers
18 views

reflection and transmission coefficients when not given information of second medium

I need help with only part (A). I am stuck on this question, i have to find transmission coefficient and reflection coeeficient. I don't know how to get this, I don't have any information from the ...
1
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0answers
37 views

Is it necessary for EM fields to be dependent & co-exist in static conditions? [closed]

I was having a discussion today with one my colleagues in the lab about the independence and co-existence of EM fields. My argument: In time-varying fields: EM fields are necessary dependent, and ...
1
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2answers
64 views

Solenoid Fail - No Force

I have designed and built a small solenoid and... it doesn't exert any force on the steel bolt I am using as a plunger. I could freely move the plunger back and forth without any resistance. I am ...
2
votes
1answer
58 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 ...
0
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0answers
72 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
58 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
2answers
380 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
1answer
72 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
56 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
56 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
137 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
151 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
65 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
62 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
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2answers
89 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
190 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
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2answers
47 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
68 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
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2answers
76 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
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0answers
53 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
761 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
91 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
58 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
372 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
136 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
168 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
62 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
22 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
57 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
641 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
109 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
74 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
104 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
120 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
57 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 ...