An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.

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How to size an electromagnet

How can I size an electromagnet? For example if I would to attract a mass of $x$ kg what are the calculations that I must do to size the ferromagnetic core and of course the solenoid? And thus, how ...
12
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5answers
926 views

Why are wires in simple circuits approximated as equipotentials?

I just answered this question: Voltage in a circuit by asserting that any two points joined only by a wire, but no other circuit elements, are at the same value of the electric potential. It is, of ...
2
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2answers
885 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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1answer
210 views

Fitting a circuit scheme to a simpler model

I have to simulate the electric field within a gas filled discharge gap generated by a radio frequency voltage generator. The circuit, provided to me by the experimenters somewhat far away, is given ...
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2answers
225 views

Voltage in a circuit

Suppose I have a following circuit: I do not understand, why the potential difference between the points $c$ and $d$ is equal to the potential difference between the points $b$ and $a$? That is, ...
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2answers
195 views

$V=IR$, isn't it missing something?

So I know that $V=IR$ works for circuits, but for the case of an arc-before the arc jumps, there is a potential difference, but no current, but there isn't infinite resistance is there? I don't ...
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2answers
603 views

How does symmetry allow a rapid determination of the current between $A$ and $B$?

The following was originally given to me as a homework question at my physics 2 course: Consider the following circuit The difference of potentials between the point $V_{1}$and the ...
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1answer
72 views

Would the empirical behavior of a simple circuit match my model of it?

I have a practical problem in E&M which has baffled me and and my electrician. The copper water pipes in my house are carrying a current of small potential (~1V) AC current. Here is my ...
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0answers
128 views

About electric current analogy

my teacher gave me this analogy to the electric current , the wire is like a pearl necklace where the pearls can move, the current or the movement of electrons is like putting your fingers between 2 ...
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2answers
764 views

How to find $\tau$ in this circuit?

1) 2) I know, that $$ τ = \frac{L}{R} $$ but what is $R$ in this formula? It seems to be the total resistance, but how to find it in 1) and 2)?
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1answer
54 views

Total current of two sources in series? [closed]

Here is a question that a friend asked me. He had to an experiment in school and do some calculations afterwards. Those calculations require maximal current that the DC source can produce. He has ...
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1answer
371 views

Question Based On Direct And Alternating Current

A Wikipedia article on Power engineering reads, Most refrigerators, air conditioners, pumps and industrial machinery use AC power whereas most computers and digital equipment use DC power. As ...
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1answer
276 views

Power in hydraulic analogy

In hydraulic analogy one compares electrical circuits with water circuits. For the electric case the formula $P = U \cdot I$ for the electric power holds. The analogous formula for water flow would ...
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1answer
482 views

Finding the Steady State Charges

Here the problem states to find the steady state charges on the condensers.<<<< According to me the charges on second at steady must be ...
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1answer
101 views

Circuit Loop Law Doubt

In a circuit with a solenoid/inductor and a resistor and a battery . Books say that $\Sigma \Delta V=0$ around a closed loop . That means work done by electrostatic field per unit charge is $0$ ...
3
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6answers
16k views

Parallel circuits - Overall resistance decreases with additional resistor [closed]

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 ...
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1answer
122 views

Current in AC circuit

The problem is to find the current on the capacitor. $I''$ should be correct, but I don't know how to construct the formula for $I'$. I managed to get the value for $I_c$ using Thevenin and Norton ...
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1answer
78 views

Doubt on the analysis of $RC$ circuit

I'm studying $RC$ circuits and I'm in doubt on how to deal with one kind of situation. Well, first when we have simply a circuit with just one resistor and one capacitor in series, or a circuit that ...
4
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2answers
698 views

Equivalent RC circuit to a RRC circuit?

I'm in doubt about a situation that I've seen sometimes: imagine we have a resistor in parallel with a resistor and a capacitor in series. Since I don't know how to generate figures of circuits to ...
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1answer
711 views

Electromotive Force Definition for Induced Current

If in DC , Emf is the work done to carry a unit positive charge from -ve to +ve terminal . What is induced EMF then , in a similar sense ? To carry a unit charge around a loop once along a fixed ...
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2answers
3k views

Voltmeter forming a closed circuit

A battery is connected to a 10Ω resistor as shown in Figure 2. The emf (electromotive force) of the battery is 6.0 V. When the switch is open the voltmeter reads 6.0 V and when it is closed it ...
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4answers
2k views

Resistors in Parallel

From my book: "A length of wire is cut into five equal pieces. The five pieces are then connected in parallel, with the resulting resistance being 2.00 Ω. What was the resistance of the ...
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2answers
18k views

Why don't electric workers get electrocuted when only touching one wire? [duplicate]

I know that when electricians work on the poles on the streets, if they only touch one wire at a time they will be fine. However, from my understanding, the negative wire is connected to a large ...
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1answer
424 views

Experiment to find Ammeter Resistance [closed]

I've been studying experimental electrodynamics and I needed to describe an experiment to find the resistance of an ammeter if I just have the ammeter together with one voltmeter and a protection ...
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3answers
7k views

What's the right way to calculate charge on a capacitor?

How much charge is on each plate of a 4.00-F capacitor when it is connected to a 12.0-V battery? I said 2.4 x 10^-5 C because there are two plates of a parallel plate capacitor. But the key said only ...
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0answers
64 views

Capacitors discharging in series [duplicate]

If you connect positive plate of a charged capacitor to ground, it doesn't get discharged. Now consider $4$ capacitors of equal capacitance connected in series to a $10\, \mathrm{V}$ battery. Connect ...
2
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1answer
841 views

How we approach RLC circult from RLGC model?

In the text, it introduces a practical model to investigate a transmission line (like BNC cable), it considers the transmission line has resistive $R$, inductance $L$, conductance $G$ and capacitance ...
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1answer
1k views

measuring electromagnetic induction

There is a famous law which says that a potential difference is produced across a conductor when it is exposed to a varying MF. But, how do you measure it to prove? It is quite practical. ...
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1answer
135 views

Confused on Calculating Resistance Distance Matrix

I am trying to create a computer program to compute the equivalent resistance over any points on any rectangular set of resistors (all with a resistance of 1 ohm). It seems that the resistance ...
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1answer
91 views

Differentiating a sinusoid [closed]

http://i.stack.imgur.com/ndLgm.png I don't see the how the author derived that $\frac { dv }{ dt } \leftrightarrow\overrightarrow { V } j\omega$.
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3answers
6k views

Calculating time for a fully charged UPS

I have a UPS of 1000 Volts connected with 2 batteries each of 150 Amp. How much time it will take to consume the whole UPS (after fully charged) when a device of 1Amp is getting electricity form that ...
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2answers
1k views

Why does a capacitor discharge?

Suppose a charged capacitor (parallel plates), the negative and positive charges on two plates attract each other. Which force cause the negative charge carriers (electrons) move through the circuit ...
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1answer
96 views

Can someone explain this intuitively please?

In a static situation we defined voltage as energy/unit charge, or j/c. As the distance between the charged particles increased, the voltage decreased. Now why do we not apply this in a simple DC ...
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0answers
152 views

Transfer functions of active filters

I've been looking for some straightforward method or trick to obtain the transfer functions of active filters (like the Sallen-Key filter, the butterworth or Cauer topology etc...) since KCL or KVL ...
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1answer
215 views

What are the statuses of Silicene and Graphene for real world circuit production?

A lot of hype is out there about both of them (especially the latter) and I was wondering if there is more concrete information about them other than the news IBM posted on a circuit 2 years ago and ...
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2answers
710 views

Out of phase voltage current source and resulting power

Examining the following graph, I am trying to understand the power plot. The power appears to take on a negative value when the current changes direction or the voltage changes polarity. Negative ...
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5answers
1k views

How long would it take for electricity to flow from one terminal to other, via a 1 LY long wire?

Basically, how long does it take for electricity to determine there is a closed circuit and how does it know that the circuit exists? I'm curious to know how it knows there is a closed circuit at any ...
5
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1answer
5k views

short circuit an alkaline battery

i'm not doing anything related to physics, but i'm just curious : What really happen when i short circuit an alkaline battery ? some article in the net shown that fire/explosion can be happened when ...
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1answer
226 views

Full wave rectification [duplicate]

In the construction of a full wave rectifier, why is there central tapping in the secondary winding of the power transformer? What's the pure reason behind it? If there was no central tapping, what ...
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2answers
515 views

Why the CFL light bulb flashes even if there is a power cut?

Today when there was a power cut I saw that the CFL light bulbs were flashing time to time at regular interval. I was amazed as there was no source of power to the CFL bulbs even they were flashing as ...
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1answer
417 views

Cable TV version of infinite ladder network [closed]

This is a problem in a college physics textbook, and its bugging me that I can't get it. The figure shows a circuit model for the transmission of an electrical signal, such as cable TV, to a large ...
3
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3answers
3k views

How much energy was consumed when we turn on/off light?

My parents told me to turn off the light when I am not using it. But I remember my physics teacher told me that the action of turning on/off a light can cause huge energy. I am wondering how much is ...
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1answer
405 views

a metal bar on a pair of conducting rails that carries a current

This is a homework question, and I solved it already, but something bugs me. So the problem is stated as following: A metal bar of mass M sits on a pair of long horizontal conducting rails separated ...
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4answers
504 views

Why is there a potential difference?

The question then asks for the potential difference between $X$ and $Y$, which is claimed to be $3.6\text{ volts}%$. Why would there be a potential difference in this case? If I connect a lightbulb ...
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1answer
153 views

Microphones, Loudspeaker and their analogies to spring mass system

I have just started studying Microphones and Loudspeakers. I need a good text to refer which can explain their mechanical analogies with simplicity and basics too.
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3answers
955 views

kirchhoff's law.Simple question [closed]

So far I calculated total resistance and it is 4.66 ohms and there is 12 volt voltage across them, what is the best way or HOW to calculate current for each resistor ?
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2answers
7k 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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1answer
775 views

AC Circuit Theory Maximum Power Transfer

I am currently hitting a barrier with regards to the basics of this question. A 50HZ supply is connected to various given impedance's, calculate the maximum power transfer. Maximum power transfer I ...
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3answers
587 views

Is this really how a capacitor works? Why doesn't it behave like a resistor?

My book says a capacitor is two conducts being connected by an insulator. Now let's take a parallel plate capacitor to simplify the problem I have. Suppose I got two parallel plate capacitor in ...
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2answers
2k views

Why and how does symmetry work in circuits?

Why symmetry work in circuits? In my book there is no mention explanation as such for symmetry arguments and circuits. But there are circuits that are very difficult to solve without symmetry. Also I ...