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

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3answers
175 views

Voltage in a parallel circuit [duplicate]

Why is voltage same across a parallel circuit? I mean what makes the voltage remain same across two resistors connected in parallel? If an electric heater is connected in parallel with a bulb and ...
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1answer
56 views

Negative charge on capacitor, Kirchoff differential equation with step function

I'm solving a differential equation of the form $$200q'+\frac{200}{3}q=3U_o-6U_6+3U_{12}$$ Where $U$ is the Heaviside step function. $q(0)=0 [Coulombs] $ After solving it, I get that at time $t=18$ ...
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5answers
1k views

Is voltage difference always proportional to its derivative?

We write, because of Ohm's law: $$V=RI(t),$$ but also we have $$C\frac{dV}{dt}=I(t).$$ From the first equation we deduce that $V\propto I$ and from the second $\dot V\propto I$. So we can conclude ...
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1answer
65 views

Questions about the formula used to determine inductive reactance and $Z_t$

I am currently on the inductors unit in my Navy schooling and I have two questions about these formulas that I learned about. As I'm aware, the ability of an inductor to concentrate a magnetic field ...
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2answers
753 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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1answer
50 views

Why is the voltage negative?

What I don't understand is why the the two voltage sources are subtracted when working out the emf for part a, The graph does not show the orientation of the solar panel so I thought I was to ...
0
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1answer
553 views

Determining energy stored in capacitor and inductor in RLC circuit

I've been stuck on the following homework problem for a few hours now with little progress. As you can see, it's a relatively simple RLC circuit with a couple independent sources and a ...
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1answer
74 views

how can we apply the formula p=VI in power transmission lines?

i mean we don't know the value of voltage across the power lines...we just know the potential at which it is generated which is not the potential difference across its ends..say electricity is ...
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1answer
163 views

Why the bulb does not glow in this configuration of batteries?

I connected a bulb to a battery positive terminals with positive and negative terminals with negative . It glows as it should but when i connect the positive terminal of the same bulb to the positive ...
2
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1answer
327 views

Calculating Boltzmann constant using semiconductor

My task from the latest laboratory exercise in physics is to calculate Boltzmann constant from known temperature, current and voltage. We were given this circuit: By changing the resistor value, I ...
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2answers
66 views

Sign conventions in Devoret Les Houches course on quantum fluctuations in electrical circuits

In this article on p. 364 Devoret writes the "equations of motion" (using KCL) for the electric circuit shown on p. 363. He uses flux instead of voltages. The sign convention he uses, as shown on p. ...
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1answer
67 views

Can we double the electric energy?

If I have $x$ amount of electrical energy and convert that into mechanical energy using an AC Motor, and then convert that energy back into electric using an AC generator, will the amount of energy ...
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1answer
64 views

2 simple Generators = Im lost (intensity) [closed]

What happens? we have 2 Generators and 2 intensities, when I2 and I3 come together (they have opposite sides ) what happens? I tried writing down the voltage relations but I'm stuck because I don't ...
2
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4answers
340 views

Justification of root mean square [duplicate]

In the top answer to the question Why do we use Root Mean Square (RMS) values when talking about AC voltage, the following was stated: This RMS is a mathematical quantity (used in many math ...
7
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3answers
6k views

Is it safe to use any wireless device during a lightning storm?

I need "educated" reasons whether it is safe to use any wireless device during a lightning storm. Most people said don't use it but they cannot explain why.
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1answer
112 views

Voltage divider example [closed]

I have the following voltage divider circuit: Now, my goal is to find U_{L}. Altough, I know already the solution (U_{L}= ...
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1answer
81 views

Solving for current in a circuit problem (image included)

I need to find $I_{R_2}$ and I need someone to explain why $I_T = I_{R_1} = 1 mA$. I thought that we were supposed to use the fact that $I_T = I_{R_1} + I_{R_2} + I_{R_3}$: ! I have solved for $R_T ...
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1answer
51 views

Capacitors in Series and Parallel [closed]

I'm working on a physics project and we're disagreeing on how to analyze a circuit. I think the circuit should be $(1/c_1 + 1/c_2)^{-1} + c_3$ and other people in my group think it should be $((c_3 + ...
0
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1answer
45 views

What is the smallest resistance that can be used in a 5 V circuit if the resistors available are rated for 1/4 W? [closed]

What is the smallest resistance that can be used in a 5 V circuit if the resistors available are rated for 1/4 W? What is kind of throwing me is that it wants the "smallest resistance that can be ...
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3answers
175 views

Explain why we use this formula to calculate total resistance [duplicate]

Why do we use this formula to find the total resistance? Lets say we have three resistors in a parallel circuit $$R_t = \frac{1}{\frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}}$$ Where does it come ...
0
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1answer
58 views

What is the ohmic value of a resistor that will dissipate 1 W when the voltage across it is 2 V?

I've been learning about Ohm's and Watt's law throughout this chapter so I'm already familiar with substituting Ohm's Law for part of Watt's law to get values. But nowhere in the chapter did it go ...
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1answer
820 views

What is the power in this circuit if the voltage is doubled?

I'm actually going ahead in the book (DC Circuits) so this isn't really homework but I figured the tag was appropriate....the name of the chapter is Ohm's Law and Watt's Law. Problem: Calculate ...
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2answers
431 views

How can there be current if all paths have same potential difference

I am learning about circuit analysis now, but there is something that I can't wrap my head around. Imagine this simple circuit: ...
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2answers
147 views

Voltage and resistors

I've read in many books and through many answers on this and other sites about this concept. Now I'm not sure what to "believe". In the subject at my university, we are taught that conducting wires ...
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4answers
2k views

Parallel or series connection?

Are C1, C2 and C3 connected in parallel, or C2, C3 in parallel and C1 in series with C23? Btw it appeared as a question in the basic physics Albanian A-levels yesterday. You had to find the ...
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4answers
12k views

How does power consumption vary with the processor frequency in a typical computer?

I am looking for an estimate on the relationship between the rate of increase of power usage as the frequency of the processor is increased. Any references to findings on this would be helpful.
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5answers
1k views

Capacitors and Resistors - Series or Parallel?

I recently came across a problem in which a 12v DC power supply is connected in parallel to (in one loop) a one microfarad capacitor and a one kilo-ohm resistor. In the other loop is a 1000 microfarad ...
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0answers
89 views

Thevenin's equivalent of Wheatstone bridge

I tried to calculate the Vos and Isc and both of them are zero..so the Thevenin's resistance is 0/0=undefined. How do I calculate the resistance when Vos/Isc fails,such like the Wheatstone ...
3
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1answer
211 views

Resonance Frequency of High Resistance RLC

I was measuring the resonance frequency of an RLC (all in series) circuit using an oscilloscope and a function generator. Now resonance frequency is given by: $$f_r = \frac{1}{2 \pi \sqrt{LC}}$$ In ...
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2answers
83 views

What really causes terminal voltage?

In class we see how a current reduces the voltage across the battery if it has internal resistance. And we see that Vterminal=EMF-Ir. We don't really see the theory behind this, and I went on to ...
0
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2answers
54 views

In low voltage (3-12V) DC applications, which is safer to be exposed or touchable + or - terminal?

The - side has a surplus of $e^{-}$s and the opposite is true for the + side of the power supply. Does it not matter, or depends on your configuration / contact with Earth? Please explain!
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1answer
41 views

What is the dormant common ground between harmonic mechanical oscilators and electromagnetical ones?

When I learnt electromagnetic oscillators I couldn't help but notice that it has many common stuff with mechanical ones. I know that it had to have sinusoidal equations. I (firstly, without ...
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1answer
592 views

Drift velocity of electrons with changing area

What would happen with the drift velocity of a cylindrical resistor's diameter increases, with a given voltage between its terminals? According to the expression: \begin{align} ...
0
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1answer
175 views

Specific differential equation in RLC circuit

I have been studying differential equations in RLC circuits: specifically I am looking at a generator with fixed EMF $=E$,a capacitor $C$, an inductor with inductance $L$ and internal resistance ...
3
votes
1answer
625 views

Power dissipation in circuits:Why is high voltage used in power lines?

I know this question has been asked before, but there is one doubt I still cannot clear. Power dissipation is proportional to $I^2R$. Does this not mean that it is also proportional to $V^2/R$? If ...
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1answer
229 views

Normal modes of two parallel $LC$ oscillators coupled via mutual inductance

Consider the circuit shown below. The two LC circuits are arranged in such a way that their mutual inductance M results in a coupling between the currents flowing in the two circuits. Find the ...
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1answer
210 views

Voltage across an inductor contradicts Lenz's law?

Imagine a simple circuit consisting of an alternating current source connected to an inductor. Assume they are connected in the following fashion: AC source - terminal A - Inductor - terminal B - AC ...
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1answer
595 views

A problem regarding equivalent resistance between two points [closed]

I came across this problem in a book which has solutions for all questions except this one. I can't get how to do this partly due my doubt whether the R and 4R resistors will get short-circuited or ...
4
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2answers
658 views

Voltage drop due to a resistor

I'm afraid this question is going to sound rather dumb but here it is: Suppose I have a very simple circuit: one battery and one resistor. The sum of the voltages in this circuit has to equal zero. ...
0
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1answer
1k views

What is the equivalent resistance of this bridge circuit?

I am trying but could not find any way of calculating the equivalent resistance of this circuit. Please help me. Should I use the Wheatstone Bridge equivalent resistance, the Y-$\Delta$ transform, or ...
0
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1answer
71 views

Why is the loop rule from circuit theory applicable for 'any' loop?

While proving Kirchoff's loop rule in class or any physics book, we take a simple one-loop system for the proof. In such a case, the current actually goes round the loop and the same current flows ...
1
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1answer
478 views

Can the electric field strength of a wire simply be calculated using the voltage / length formula?

Can the electric field strength of a wire simply be calculated using the voltage / length formula: Electric Field Strength = Voltage Across Wire/ Length of Wire I am asking about a wire with current ...
0
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0answers
36 views

Why is voltage input different from voltage output in a circuit?

This is more specifically, when performing the meter bridge experiment. The meter bridge experiment is an experiment in which using the meter bridge, a jockey, voltmeter, battery eliminator, you keep ...
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0answers
25 views

Is it possible that intermittent current is being passed in a circuit with loose connections at less than maximum capacity?

In a circuit, the wires may not have been connected properly and a connection is loose somewhere. Is it possible that intermittent current is being passed in a circuit at less than maximum capacity?
2
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0answers
35 views

Why is the current measured through a thin film increasing with time? (experimental question)

I'm doing an experiment: I'm thermally evaporating a metal in a vacuum onto a quartz (very insulating) substrate, between two gold contacts that I use to measure the current through the (growing) ...
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0answers
212 views

Energy of RLC circuit

If you are given a general differential equation for an RLC circuit, for example, $$L\left(\frac{d^2 Q}{dt^2}\right) + R\left(\frac{dQ}{dt}\right) + \frac QC = V\cos(\omega t),$$ which is a driven ...
3
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4answers
849 views

Application of Kirchhoff's laws in circuits with inductors

As we know,the Kirchhoff circuit laws are applicable for conservative electric fields. Now it is applicable for circuits where inductors are present but the field there is not conservative. So how ...
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1answer
589 views

The shape of the graph of the equation: $V= -r I + E$

I have recently collected data (for a school experiment) in order to measure the EMF and the internal resistance of a solar cell. The data complied with the equation: $V = -rI + E$, i.e. the voltage ...
0
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2answers
193 views

Calculating emf with and without resistance

A battery of internal resistance 2 Ohms is connected to an external resistance of 10 ohms. The current is .5 A. What is the emf of the battery? The correct answer is 6.0 V. When I calculated it like ...
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2answers
2k views

Why does the thickness of a wire affect resistance?

For small thicknesses of wire, it's pretty obvious why resistance affects thickness. (The electronics squeeze to get through). But after a certain thickness shouldn't the thickness become irrelevant? ...