The current tag has no wiki summary.
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21 views
Current distribution in inductors
I have been trying to figure out how current is distributed in a circuit with multiple inductors. I could not find any specific info regarding the topic but I guess it is similar to the case with ...
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0answers
23 views
Increasing Amps [closed]
I am not sure if this is the place to post this, but both physists and electricians should be able to help here, so I am going to cross post with DIY (sorry if this really annoys people - I know it ...
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1answer
25 views
Why should a battery not give current in order to measure EMF?
Emf is the "potential difference (PD) across the terminals of a battery when it is giving no current to the circuit."
What does "when it is giving no current mean"? Will the PD across the terminals ...
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2answers
42 views
Electric power transmission
If we want to transmit electic current for a long distance, we must minimize a heat that releases because of the resistanse. We cannot make a cable wide because it is expensive and it will be massive. ...
4
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2answers
89 views
Can a current carrying loop or wire produces no magnetic field?
A current carrying wire produces magnetic field around it. We can find the direction by Fleming's Right hand rule. We know change in electric filed produces magnetic field and change on magnetic field ...
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1answer
45 views
Volts, Amps, and Practical Electrical Knowledge
I've heard people say that high amperage or high voltage is dangerous to humans-aren't they both? And what are the advantages to high amperage versus high voltage? And how do you generate one or the ...
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2answers
80 views
Currents and the Speed of Light
Why is it that currents don't flow at the speed of light, but rather significant ratios of the speed of light.
I don't have any formal reasoning as to why they would flow at the speed of light-I just ...
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1answer
21 views
Speakers and Static from Hands
Why is it that when you touch the a bare male end of a speaker feed that the speaker makes hissing noises? Is it just (eddy?) currents running through you?
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2answers
90 views
Simple ohms law on a battery ? Paradox or conceptual error?
Suppose we have a regular pencil battery which supplies DC voltage $V$. Say we take copper wire and connect the ends of the battery to an $R$ ohms resistance.
Then Ohm's law tells use the current in ...
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1answer
69 views
iPhone compass not being affected by current
As you probably know, electrical current and magnetic fields are close friends.
In an iPhone there is a compass, however there are also lots of cables and in all of them, or at least in most of them ...
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4answers
62 views
North and south of magnetic field
The current I is flowing upward in the wire in this figure. The direction of the magnetic filed due to the current can be determined by the right hand rule.
Can we determine the north and the south ...
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3answers
177 views
There must be free positive charges, moving oppositely to electrons for the wire with current to stay neutral
All popular expositions (e.g. these ones) of relativistic electromagnetism claim univocally that electrons in motion become more dense due to the speed. They teach that Lorentz contraction of charges ...
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2answers
84 views
What does it mean for electric current to be a scalar?
After reading the reasons for considering electric current as a scalar quantity, I was confused at a point which read "The magnitude and direction of current does not depend upon the direction of the ...
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1answer
113 views
Is it possible create current by spinning a charged sphere?
If we have a sphere which has $σ$ surface charge density and rotate it in axis z will this create current ? Is it possible without any potential difference ?
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2answers
46 views
Light bulbs, Wattage meaning? [closed]
Light bulbs, Wattage meaning?
Two incandescent bulbs (120 V, 25 Watt) and (120 V, 500 Watt) connected to the same batteries.
Which one shines brighter? And why?
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1answer
43 views
Understanding drift velocities in currents
I have a doubt about the understanding of drift velocities in a current. My problem is that the textbook speaks very loosely about this. It's like: "well, if we apply a field $E$ then the charges will ...
1
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1answer
38 views
Negative emf in AC generator
At a certain instant in AC generator, when the normal of the plane (rectangular coil) makes an angle of 270 degrees with with the magnetic induction B, the value of emf is:
$E = -NAB\omega$
My ...
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0answers
57 views
Current between supeconducting rings
How to calculate the current between two superconducting rings with radius r separated by a distance d?
Please note that being unfamiliar to the concept of superconducting rings, I can't approach ...
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0answers
139 views
supersymmetric Noether theorem and supercurrents — invariance requirements
Consider $\mathcal{N}=1,d=4$ SUSY, $n$ chiral superfields $\Phi^i,$ Kaehler potential $K,$ superpotential $W$ and action ($\overline{\Phi}_i$ is complex conjugate of $\Phi^i$)
$$ S= \int d^4x \left[ ...
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0answers
18 views
What works on 8-10 volts, 4 milli amps, and is not hardwired? [closed]
I want to know what is the smallest device that can work on a few milli amps? I know a NE-2 neon bulb works on less than 10 mAmp but on 90 volts at least.
I need to find a small device that:
1- ...
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0answers
17 views
What is the principle of active voltage balancing/equalizing device?
I am wondering about active voltage sharing devices. Their purpose is to equally divide voltages on slightly unequal super-capacitors. I found some papers like this, but it is too scientific.
I want ...
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1answer
67 views
AC passed to a DC motor
What would happen when an alternating current (AC) is passed to a DC motor? And a direct current (DC) passed to an AC motor?
Will it work or not?
What will happen to it?
2
votes
1answer
159 views
Frequency Response RLC circuit - Current against Frequency graph - Symmetry?
I understand that in a Frequency Response experiment dealing with an RLC circuit, the graph of Current against Frequency is supposed to be symmetrical about the resonant frequency theoretically.
...
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0answers
39 views
Magnetic field at a point [closed]
Find the magnetic field near a straight current carrying conductor of Length $L$ and current $I$, at point located along the perpendicular bisector of the wire a distance $r$ from the wire. Show all ...
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3answers
569 views
Why is AC more “dangerous” than DC?
After going through several forums, I became more confused whether it is DC or AC that is more dangerous. In my text book, it is written that the peak value of AC is greater than that of DC, which is ...
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1answer
121 views
Eddy current losses in electric steel by harmonics of a magnetic field
I am working on an model of a permanent magnet synchronous machine. Right now I am stuck with calculating the eddy current losses caused by the harmonics of the stator magnetic field in the electrical ...
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3answers
150 views
How exactly does a resistance reduce current?
I've heard that resistors are used to decrease current to a particular appliance, such as in the regulator of a fan. However, I've also heard that the total current in a circuit is always the same- in ...
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4answers
110 views
Why in $F = iLB$, $L$ is a vector but $i$ is not?
I learned $F = iLB$ recently. However, I don't understand why $L$ is marked as a vector but $i$ is not.
For a normal rod, how should I define the direction of length vector $L$? And if I reverse the ...
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1answer
61 views
how to find the diameter of this fuse? [closed]
A fuse blows if the current exceeds 1.0 A. It is made of material that melts at a current density
of 620A/cm2. What is the diameter of the wire, assumed to have a circular profile, in the
fuse?
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0answers
43 views
Object accelerated by electromagnet
If I have an electromagnet (powered by a battery) and a metallic object, the
power generated will depend on the voltage of the battery and the resistance of the coil.
If I accelerate the object, will ...
1
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1answer
58 views
current electricity and voltaic cell
let us consider that i have a voltaic cell in an open circuit that has copper plate at higher potential w.r.t zinc plate. Now my query is, since the electrolyte separating them is a conducting medium, ...
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5answers
586 views
Parallel circuits - Overall resistance decreases with additional resistor
Let's say that there is a parallel circuit with two identical resistors in parallel with each other. If a third resistor, identical to the other two, is added in parallel with the first two, the ...
2
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2answers
299 views
Round bulb and Long bulb in Series Circuit
If you have a series circuit with a battery, one round bulb (with thicker filament), and one long bulb (with thinner filament), the round bulb does not light up and only the long bulb lights up.
...
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2answers
414 views
Capacitor circuits with light bulb
Let's say we have a normal circuit with a light bulb, with wires and a battery.
When one places a capacitor in this circuit, how is the light bulb able to light up, even when the capacitor prevents ...
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1answer
479 views
Relationship between resistance and voltage drop
In a series or parallel circuit, if two bulbs have the same resistance, do they have the same voltage drops? The problem I am asking about is below. Do A, B, and C have the same voltage drops since ...
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1answer
88 views
Which of these two methods is correct for calculating current?
I recently came across a question, for which I saw two possible methods of finding the solution. I was required to calculate the "current flowing" $I$ when given the voltage $V$, frequency $f$, total ...
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6answers
312 views
Is voltage electric potential or electric potential difference?
On Wikipedia, voltage is defined to be the electric potential difference. However, I am still not certain as to whether voltage is the electric potential ($PE/q$) or electric potential change ...
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3answers
146 views
How is possible for current to flow so fast when charge flows so slow?
How is possible for current to flow so fast when charge flows so slow?
We know electrons travel very slowly while charge travels at ~the speed of light.
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2answers
574 views
Ohmic and Non-Ohmic devices
Why do some conductors follow Ohm's law and some do not? Isn't there any universal law that can explain the flow of current?
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2answers
207 views
Why does the current stay the same in a circuit?
I was informed that in a circuit, the current will stay the same, and this is why the lightbulbs will light up (because in order for the current to stay the same, the drift speed of the electrons need ...
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2answers
103 views
Under what condition charges do not flow in closed circuit?
I wanted to ask under what conditions will charges not flow in a closed circuit. Or when is current through the circuit zero even when an EMF is applied?
Like in the case of potentiometer, we say that ...
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2answers
197 views
Flow of electrons in a circuit
When the electrons flow in a circuit, so are those the electrons from the battery or are those the electrons of conductor like copper wire, etc..which are flowing in the circuit?
2
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1answer
154 views
Positive test charge
Protons have positive charge on them. Protons aren't mobile. So how can a positive test charge move from the negative terminal of a cell to the positive terminal and gain electric potential energy? ...
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0answers
143 views
RMS value of the A.C. current? [closed]
What is the RMS value of current $i=3+4sin(\omega t+\pi/3)$?
Please give step by step solution.
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1answer
341 views
Current without Voltage and Voltage without Current?
At school I've always learned that you can view Current and Voltage like this:
The current is the flow of charge per second and the Voltage is how badly the current 'wants' to flow.
But I'm having ...
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1answer
196 views
What kills you: Voltage or Electric current? [duplicate]
Possible Duplicate:
What causes an electric shock - Current or Voltage?
When someone gets electrocuted, what kills them; a high Voltage or a high Electric current, and why?
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1answer
147 views
What does the current vs voltage graph of a halogen look like?
I have a halogen light with a tungsten filament. It is rated 500w at 130v but I am running it from an inverter in my car that is putting out 110v. I would like to know what the actual power usage of ...
0
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3answers
291 views
charge density in a wire
if we have a infinitely thin and infinitely long straight wire on the z-Axis with given current I(t), how can i compute the charge density?
I figured out that the current-density is given by ...
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1answer
119 views
Physical explanation for capacitive circuit
In capacitive circuit, the voltage and current are out of phase. the current leads the voltage by 90 degrees. this can be explained by these two equations:
$$V = V_{\max} \sin \omega t$$
$$I = ...
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2answers
55 views
A flammable gas in a energized conductive container
I place a flammable gas (natural gas) inside a metal container and energize the container (apply AC current). Do I have any concerns at this point. I understand for combustion to occur I have to ...
