Questions tagged [electric-circuits]

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

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2answers
32 views

Why/when is an indirect AC - DC - AC frequency converter superior to a direct AC-AC frequency converter? [on hold]

I am currently studying wind power and the power electronics used for it. In wind power a generator is driven by wind, thus the resulting power is of widely varying frequency and amplitude. The power ...
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4answers
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How is it possible for the induced emf to take negative values in Faraday's Law of induction?

Faraday's Law of induction states that the work done per unit charge by the (induced) electric force along a loop of wire, or the emf, is minus the rate of change of magnetic flux through the loop/...
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Current in Wheatstone bridge

When the galvanometer and cell are interchanged at the balance point of the Wheatstone bridge, the galvanometer will show no deflection. There is no change due to the shifting of the position of cell ...
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52 views

Conflicting models about how energy transferred in an electric circuit [duplicate]

I've been studying DC circuits recently, but I've run into some confusion concerning how batteries deliver energy to circuit elements. From what I've read online, it seems that energy in circuits ...
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Zener diode as a voltage regulator [on hold]

I tried to solve the following exam problem. The problem asks to find a range of load resistor values for which the circuit can be used as a voltage regulator satisfactorily. My question is; What '...
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How do I calculate the total resistance of this circuit? [on hold]

How do I calculate the total resistance of this circuit? From the data from a site it can be calculated that the total resistance is $\frac{12\ V}{5.14\ A}$ which is $2.33\space \Omega$. But I don't ...
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1answer
35 views

How to increase Sensitivity and precision of a measuring sensor?

Considering the definition that Sensitivity: Relation between the maximum of range, the sensor can $\frac{i}{p}$ to the corresponding $\frac{o}{p}$ given by the sensor due to it. Ex: A pressure ...
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Calculate the power supplied by voltage source [on hold]

Hi for this question (sorry about the picture), if the current source ($2A$) receives $20 W$ of Power, determine the $R$ of the resistor and the power of the voltage source. I sort of know I have to ...
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Why are there many turns in the primary coil of a step-up electricity transformer?

Since the voltage in a coil is proportional to the number of turns, the ratio of voltages is equal to the ratio of turns. So if you need a big increase in voltage, what stops you from having one turn ...
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Why does self-inductance still allow variation of current in circuit?

Taking a solenoid as an example, when constant current $i$ is passed through the solenoid constant flux is seen. But when the current starts to vary, the magnetic field created by a changing current ...
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Minimum and Maximum values of Effective Resistance [closed]

Assume we have resistors of resistances $R_1$, $R_2$, $\ldots$ , $R_n$. Let these resistances be connected in a network. Are the following statements true? $(i)$ Effective Resistance is maximum when ...
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Are my voltmeter readings expected for a correct chua's circuit?

I am following this article Robust OP Amp Realization of Chua's Circuit by Kennedy to implement a Chua's circuit. I use exactly the same design as the article; the only difference is that I use a 15mH ...
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1answer
32 views

Potential drop across inductors in DC circuits

The potential drop across an inductor is equal to $L(di/dt)$ where $L$ is inductance coefficient. But according to this in a DC circuit there should be no potential drop across the inductor (because $...
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Why voltage is same across parallel resistance?

Since voltage stands for energy per unit charge to be used to carry it from one point to another,why should energy per unit charge be same for two resistors of different resistances,?the energy ...
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Does a constant current source supply constant current even with voltage changes?

I found that constant current sources have a large internal resistance compared to the load resistance which keeps the current constant despite changes in the load resistance. Will this constant ...
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Differential equation of Serial RL which are connected to parallel C [on hold]

I have a serial RL which are connected to a capacitor in parallel I'm trying to find the governing differential equation of the circuit. So far, I have tried using Kirchhoff's laws for current ...
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3answers
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Electric potential and drift speed of electrons through circuit

What I have since learned: (Tell me If I am wrong) In circuits ,Batteries provide electric potential difference (voltage) ,This difference creates electric field (Over the conductor or the wire) ...
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How do I calculate the capacity of a capacitor [closed]

that is hooked on sinus voltage source $ V(t)= 100 \sqrt {2} sin(10^3t) $ $ V $ if the value of electric current $ I $ flowing thru the capacitor is $ 1 A $ ? do I transform $ V(t) $ to a phase form? ...
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Is this explanation of Voltage Drop correct?

As a general outline of what happens when the battery is turned on, here is what happens: When the battery is turned on, a wave propagates within the circuit to determine the current of the sytem.At ...
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A complete solution of an LC ladder [closed]

i am trying to solve the following system an AC power source $V(t)=V_0cos(\omega t)$ is connected to the circuit as shown in the image above i am trying to find $V_n$ and $I_n(t)$ where $V_1(t)$ is ...
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1answer
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Why should the relation (current density)= (resistivity)×(velocity of charge) [$j = ρ v$] be applied to each type of charge carriers separately?

This is from the class 12 physics NCERT Part I. The relation $\mathbf{j} = \rho\mathbf{v}$ should be applied to each type of charge carriers eeparately. In a conducting wire, the total current ...
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Chua's Circuit: an inequality ensuring that the equilibrium is not stable

According to Kennedy's Robust op-amp realization of Chua's circuit(1992), the differential equations satisfied by several physical quantities in Chua's circuit are $$\begin{aligned} C_{1} \frac{d v_{...
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1answer
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Chua's circuit: Is $x=y=z=0$ a stable equilibrium?

According to this wikipedia page, the differential equations satisfied by several physical quantities in Chua's circuit is (What each letter represents doesn't matter that much in this question) For ...
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54 views

Why does have a shunt resistance in parallel to a galavanometer decrease the amount of current passing through the galvanometer?

The way I understand it is that when you put shunt the current starts flowing more into the shunt resistance than the galvanometer, Then how can galvanometer give a correct value for actual current of ...
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Electric current and drift velocity

I have seen in several textbooks that say that when we connect a conductor with a battery then electrons start moving (drifting) in the battery in random up and down motion in the opposite direction ...
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1answer
36 views

Forces inside battery

The title itself seems silly to me but here is this question, A constant electric force of $8\ \text{N}$ acts in the direction shown and constant non electric force of $10\ \text{N}$ acts rightward, ...
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1answer
42 views

Electric field in a circuit

The electric field is defined mathematically as a vector field that associates to each point in space the (electrostatic or Coulomb) force per unit of charge exerted on an infinitesimal positive test ...
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2answers
38 views

Resistance between steel wires in water delayed response

I am trying to make a wire wave gauge by measuring the resistance between two stainless steel wires. Theoretically, the output voltage reading should change the deeper the wires are in the water. If ...
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1answer
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Proof of the superposition theorem in linear circuit analysis

I couldn't find a proof of the superposition theorem from circuit analysis anywhere online. I thought it might be helpful to ask and provide my proposed proof as an answer to gather feedback and ...
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RC Circuits- Charge and Energy

It takes longer for the charge in an RC circuit to fall down to half its initial value than for the stored energy. Why?
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1answer
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In a circuit, do surface charges get influenced by external electric fields?

Hello ,This image represents surface charges in a circuit caused by the battery's electric field, if you were to place an other electric field source of the same magnitude (but not connecting it to ...
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Is the flow of charges in inductor though electric field zero?

How electric field inside the wire of an inductor is zero (i.e. material of which loop is made — note material is assumed to be a superconductor), then how electrons flow in an inductor if electric ...
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In a circuit having one resistor why do the electrons lose all their potential energy across that resistor and not do so if there are many resistors

In a simple circuit which consists of a battery and one resistor, why do electrons lose all their potential energy across this one resistor regardless of the magnitude of the voltage or the resistance?...
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1answer
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How does the battery do work on the electron although the speed of electrons is constant

In a simple circuit how does the battery do work on the electrons of the wire although their speed is constant . Imagine I want to take a body which has 5 Newtons weight from the ground to 10 meters ...
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1answer
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Biot - Savart Law and time - variable current [duplicate]

Is the Biot Savart law valid also with currents which are functions of time (for instance a sine wave)?
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1answer
60 views

What makes the internal resistance of a battery at microscopic level?

What makes the internal resistance of a battery at the microscopic level? And why does voltage drop when in a circuit compared to the open circuit voltage? I think that the field between the ...
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1answer
59 views

How is the rate of current change in an inductor present in a circuit maintained / decreased?

Considering an ideal circuit of DC voltage source and an inductor connected together with a switch in between them. When the switch is closed at t=0 the current starts increasing which causes induced ...
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1answer
39 views

Why is neper frequency called a frequency?

In the context of complex frequency of RLC circuits, the real part is called neper frequency, according to units it's understandable that it has 1/s as the unit which is same as frequency but what is ...
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How do resistors generate different heat if we make the current fixed and changed the voltage and resistance? Notice the flow of charge is constant

Consider having a circuit which consists of a battery and one resistor. $V = 10$ volts, $R = 5$ ohms, so $I = 2$ Amperes, and $P = 20$ watts. If we double the voltage and resistance, the current ...
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1answer
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What is the theoretical maximum efficiency for LEDs?

Whatever efficiency you want to give in converting electricity to light. I'm guessing it would depend on the type of LED. I imagine limitations come from various reasons. It would be cool if there ...
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80 views

Does increasing the length of wire increase the work (energy) needed to move electrons from the negative terminal to the positive one?

Imagine a circuit which consists of a battery and a resistor with a certain wire length. Suppose that the batter supplies 9 Volts. I know that it is the electromotive force which pushes the electrons ...
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1answer
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Is resistance determined by electron mobility?

How Is resistance determined by electron mobility for a given resistor or wire.
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45 views

Heat developed in a circuit

Suppose I have a simple circuit with capacitors, a battery and a key. There Is a change in energy stored in capacitors when the key is closed. How will I find the heat developed in the system? Is the ...
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Electrolyte and internal resistance

If you have a Daniell cell(zinc / copper), excess charges will build up on the electrodes making the open circuit voltage until the reactions halt. Now in normal situation when you connect their ...
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Are the plates of a battery really charged?

In a zinc/copper Daniell cell correct me if I am wrong : Zinc has 2 valence electrons. So it wants to get rid of them. To do so it sends them to the copper which needs 2 to complete its valence ...
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536 views

Confusion in understanding the behavior of inductor in RL circuit with DC source

When we have a DC voltage source with a switch in series with $RL$ and the switch is closed at $t=0$ then it is said that current is zero initially, but the voltage across inductor is same as that of ...
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Does electric field vary with cross sectional area in a non uniform current carrying conductor?

Suoppose I have a non uniform conductor which is kept in a uniform electric field maintaining a constant potential difference across its ends.Both electric field and current density are a properties ...
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1answer
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Rates of charging in an RC circuit when components are partly charged initially

Just to be sure of my reasoning I am describing a simplified version of my problem Two capacitors of capacitance $C_1$ and $C_2$ are connected in series to a battery of emf $V$ volts having some ...