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

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How long can a cellphone battery(pictured) power a LED light that produces light equivalent to traditional 60W bulb(800 lumens)?

Assuming Energy Star rated LEDs which produces 100 lumens/watts. Battery rated as 9.88Wh. Power consumption by LED = 800 lumens/100lumens/watt = 8 Watts Does it mean that it will power circuit for ...
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1answer
9 views

Calculating half power frequency (frequency response)

I am having a doubt in calculating half power frequency for a given RLC AC circuit. I have attached images of two questions with their solutions. In the first question, the equation for ...
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0answers
19 views

Finding current in the circuit 4 [on hold]

When switch is at position 1, current occur in circuit. After a while current increases and time=t, switch is at position 2. What is the current at time t?
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1answer
46 views

Cryptic remark in physics revision guide

I am currently revising for my AP physics and I couldn't understand one of the end-of-section summary notes. It says: "Remember that the direction of magnetic field is from North to South, and that ...
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1answer
30 views

Diodes in AC current

If in AC current, the direction of the current is always changing, then if one was to place a diode (for simplicities sake lets say an LED) in an AC current, would it flash to the frequency of the ...
-1
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0answers
23 views

Resistance of symmetric resistor network [on hold]

Just doing some general Physics questions and this came up: I'm confident that I could answer the effective resistance part of the question, but am unclear as to the reasoning required for the ...
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1answer
21 views

Faraday's Law: Current loop and proton

A single circular loop of wire with radius R carries a large clockwise current I(loop)=I0, which constrains a proton of mass M and charge e to travel in a small circle of radius r at constant speed ...
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1answer
25 views

Question on an unbalanced Wheatstone bridge

Let, P/Q = R/S in the usual sense of a Wheatstone bridge where PQRS are resistances. Then we know that the potential between midpoints of PQ and RS are equal and there's no potential difference ...
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1answer
14 views

A problem based on Joule's law and specific heat [on hold]

If a wire of resistance $20\Omega$ is covered with ice and a voltage of $210V$ is applied across the wire, then rate of melting of ice will be? I calculated heat produced by the wire by using ...
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Is current in superconductors infinite? If they have 0 resistance then I (V/R) should be infinite?

I learned many years ago that according to Ohm's law, current is equal to voltage divided by resistance. Now if superconductors have zero resistance then the current should be infinite. Moreover the ...
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1answer
24 views

Why doesn't the electric potential constantly decrease in a circuit as the current moves from the positive to the negative terminal?

Why doesn't the electric potential constantly decrease in a circuit as the current moves from the positive to the negative terminal? Details and Assumptions: 1. The wires show no resistance.
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18 views

Kirchhoff's junction and loop rules [closed]

How does the conservation of charge justify Krchhoff's loop rule. Also, how does the conservation of energy justify the junction rule?
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0answers
19 views

What is the theoretical reasoning behind calculating emfs in series or parallel?

First off, I did some research on my own but the answers weren't satisfactory. The analogy of the water pump makes zero sense as I see no way how "Potential" is even comparable with "Dynamic ...
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0answers
26 views

RC Circuit Analysis

I want to correct three misunderstandings about the following RC circuit. 1) How does current move directly after switch S gets closed? Current runs through all three circuit components to begin ...
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0answers
30 views

Fastest converging series of resistors

I am looking for a recursive circuit which grows very fast and has a finite resistance but an infinite number of resistors. I have found many ways to get a finite given resistance with an infinite ...
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1answer
31 views

How can I physically demonstrate potential difference in a circuit to a 14 year old?

Children of this age have a fair idea about current, resistance, and batteries. Potential difference is a thing that cannot be felt or physically visualized. A teenager asked me if he can touch ...
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1answer
22 views

Circuit with inductor

How would I find the current through each resistor/inductor as a function of time? I am lost conceptually here. (I made these numbers up, so they may not be "pretty" if/when taking equivalent ...
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0answers
28 views

Origin of chaos in Chua's circuit

I am doing a project on Chua's circuit, but I can't seem to find anything that explains where the chaotic nature of the system comes from. Does anyone know of articles that explain it well on an ...
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1answer
29 views

How can I rearrange an equation to find a gradient for a capacitor?

If I plot R on the x axis and T on the y axis to give a straight line graph, and I am given that $V$ = $V_0$ * e^(-t/RC) then how can I prove that the gradient of the graph is equivalent to $C$ * ln3, ...
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3answers
214 views

Finding current in the circuit

Hi anyone. I try to de-draw the circuit in the simpler to calculate i1 and i2. But can not. Anyone have any hint to do this question ? . Or just give me the specific name of the way of how to do ...
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2answers
56 views

Homework: electrical circuit with 2 voltage sources & 1 switch

I can't figure out how to handle this circuit. I am asked to calculate the total resistance and the current over each resistance (R1-R4) when the switch is open. However I'm not getting anywhere ...
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0answers
10 views

Wave velocity (R)LC circuits.

I'm attempting to simulate some fluid like mechanics using circuits. Specifically wave propagation. I am attempting to measure the wave propagation velocity using an oscilloscope on the circuit below, ...
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0answers
40 views

Does earth conduct electricity?

if we connected a voltage source with its two terminals in the earth does it conduct electricity ? and why they use something like " ground or earth " in safety to let the residual charges go to the ...
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0answers
5 views

Why is the voltage drop across this transistor the full voltage of the battery? [migrated]

I am currently learning about transistors from allaboutcircuits.com. He presented the following schematic: He claims that when the transistor is in its cutoff state, V.output will read the full ...
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0answers
25 views

How do I find the electron confinement energies in a spherical quantum dot?

So if I've got a spherical quantum dot, we'll say it has a 10nm diameter for simplicity. This dot is a semiconductor and it has an electron with an effective mass altered by a factor of 0.2. How do I ...
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0answers
15 views

How does one measure the power factor?

How does one measure the power factor? $$\text{power factor}\equiv\frac{\text{power}}{|V||I|}=\frac{R}{\sqrt{R^2+(1/\omega^2C^2)}}$$ for an RC circuit driven with $V(t)=V_0\cos{(\omega t)}$.
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1answer
65 views

Shouldn't the currents be time-continuous here?

My intuition is that the current upon an inductor (say, a solenoid) will always be time-continuous, without "sudden changes". But below is a case that seemingly contradicts this point of view. There ...
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1answer
25 views

self inductance basic example: meaning of current flow AFTER opening circuit

while studying self-inductiance, I got into a tricky point... Consider this video: https://www.youtube.com/watch?v=0IVJaXO_0XA (minute 13.00). At this moment, opening of the R-L circuit is ...
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3answers
42 views

How does the voltage across an inductor and a capacitor vary in series LCR circuit about resonance?

I am aware that at resonance, the voltage across the inductor and the capacitor are equal in magnitude and opposite in phase. However, I want to know how the voltage across $L$ and $C$ vary if I vary ...
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2answers
39 views

Simple Circuits [closed]

I have a small and easy dilemma, judging by how sophisticated the website is, and need a simple answer for it So $P=E/t$. And $P=I*V$. Therefore $E/t=I*V$. I just need an explanation on how this is ...
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1answer
54 views

Wheatstone bridge intuition - and the potential divider

I am having trouble understanding the working of a Wheatstone bridge. I am looking for an intuitive understanding of the process. Basically, I would like to have the following questions answered: ...
4
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2answers
635 views

Do the copper connectors we used in measuring the resistance of a wire contribute to the said measurement?

We measured the resistance of a wire by setting the multimeter to ohmmeter mode and connected the ends of the ohmmeter to the ends of the wire; and we also calculated the theoretical value using a ...
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0answers
11 views

Induced-EMF in a parallel circuit, vs a series circuit?

I wanted to know the difference between the induced-EMF in a series circuit layout, vs a parallel circuit layout. In a series the current would stay the same,however, the induced-EMF would increase? ...
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2answers
70 views

Which lamp is brighter, the one through which electrons flow or current

I was thinking about problem that i don't really know the answer to. A circuit is set up with one battery and two identical lamps in series. Like so I know that electrons flow in the opposite ...
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1answer
50 views

How to find the voltage?

How to find the voltage ? Given is the following mixed circuit below, every resistor has the value $1$ ohm, the current flow through the last resistor is $1$A and I have to find the voltage V ...
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0answers
14 views

What is Switch Contact Rating? [migrated]

If Contact Rating of switch is 5A 240V AC & 0.25A 240 DC, Then is this switch can be used for contact rating of 220V (+10, -15% voltage variation) AC & 127V (+10, -15% voltage variation)
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1answer
28 views

Power dissipation across resistors in series

Suppose we have a simple circuit with an input voltage source $V$ and two resistors. Now if we want to find the power dissipated by each resistor using the formula $V^2/R$, should the voltage be the ...
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1answer
34 views

Explanation for: A monopole antenna must contain a resistor (or equivalent) and therefore must have 2 terminals?

Could someone explain why this sentence makes sense: A monopole antenna transfers energy from electrical domain to the electromagnetic domain, hence must contain (equivalently) a resistor, hence ...
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1answer
16 views

According to the Kirchhoff's law, what's the ratio between currents in output branches of a node?

How the current distribute in branches of a node in a circuit? Is it randomly? Can it be zero in an output branch when all branches have ~same physical features? For example, suppose the current as ...
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1answer
55 views

Equivalent Capacitance [closed]

What is the equivalent capacitance between A and B?
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1answer
34 views

Potential Difference between 2 points in a curcuit

3 Cells and 3 capacitors are connected as shown in the diagram. What is the potential difference between points A and B ? What are the final charges on each of the plates of the Capacitor ? Does the ...
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3answers
36 views

EMF in circuits help?

Can someone explain EMF in the most simple way possible? I understand the equation i.e. $ε=I(R+r)$ but don't fully understand what is going on in the circuit.
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1answer
34 views

What is the difference in the behaviour of the commutator in a motor between DC and AC?

Is it correct to say that in DC, the split ring commutator produces direct current flow and therefore stronger voltage, as opposed to AC which produces alternating current and therefore weaker ...
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1answer
36 views

Final charges on Capacitors connected in a curcuit

Capacitor C1 is charged to a Potential Difference of 10V. It's capacitance is 2 microFarad. Capacitor C2 is charged to a Potential Difference of 15V. It's capacitance is 4 microFarad. Now the ...
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1answer
44 views

The Electric Quadrupole

I've read the following sentence: "Every electric circuit with two pairs of accessible terminals is called a quadrupole." I was wondering why does it happen that the multipole expansion gives us a ...
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2answers
47 views

How does Ohm's law relate to transferring energy?

Potential difference = Current x Resistance where Resistance is a constant. Walking through a circuit I have 1 battery, a wire and 2 components. I start of with 6 volts at the battery and after the ...
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1answer
51 views

Need help understanding a simple circuit in-depth

I would like to know more in detail what's really going on in a simple circuit like this. I think I understand it, but I have a lot of things mixed up and others aren't clear to me. I'm going to ...
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2answers
40 views

Kirchoffs voltage law [closed]

There are many books which relate KVL with law of conservation of energy and I'm having trouble understanding how they are related so can anyone explain their relation to me, concept wise and if ...
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2answers
48 views

Resistor and voltage

Considering this simple circuit : The potential is supposed to be constant along each wire (because they're conductors), such that the left wire in its entirety is at the same potential as the ...
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1answer
29 views

Arcing through an inductor

When a current is passed through an inductor coil, potential difference across it is given as $$V=L\frac{dI}{dt} \, .$$ Now, if we suddenly disconnect the coil from the circuit, the current will ...