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

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2answers
24 views

Inductor circuit

Consider a inductor circuit with an inductor connected to a DC battery and a switch. Initially the switch is open. At time $t=0$ the switch is closed. What will happen to the inductor just after the ...
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1answer
35 views

Deriving the charge as a function of time in a discharging capacitor

There is obviously something I have not understood well. In Kirchoff's second law, we take the potential difference of batteries and capacitors with the sign that we traverse it. So, let's assume that ...
1
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2answers
31 views

DC motor, bulbs

What happens when you are getting low voltages ? Why fan becomes slow and bulb become dim ? Dye to low voltage or current? If power is V*I then due to low voltage current becomes low or not Many ...
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0answers
23 views

Impedance of transformers

What does mean by impedance reflecting? Why this phenomena occur? What does mean by Zl=zs to gain max power but power is constant in transformers?
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1answer
34 views

Equivalence between voltage drop across capacitors and resistors?

In simulating a circuit, comprised of 2 capacitors of same size but different dielectrics, their capacitance ratio ${C1}/{C2} = \epsilon2/\epsilon1$. Problem is, in finite element programs, I am ...
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1answer
632 views

How to imagine the first few moments of an LR circuit?

For example, there's a very simple circuit which only contains on resistor. So according to Ohm's law, we have: $\mathrm{emf} = IR$ As we know when time $t = 0$, the current must be $I = 0$. However, ...
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1answer
51 views

AC Electricity as a Simple Harmonic Oscillator

Can the net motion of electrons in an AC circuit be considered an example of simple harmonic oscillation. Furthermore, how can the general formulae of SHM be adapted to suit a scenario of an AC ...
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0answers
22 views

Triphasor Problem

Given the data presented in the following link I have to get $R$ for $P = 90~\textrm{kW}$ and the line currents $i_1$, $i_2$ and $i_3$. Any ideas?
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1answer
66 views

Validity of Kirchhoff's current law

Is Kirchhoff's current law valid for rapidly varying currents such as a one with a frequency in the order of 10KHz?
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1answer
38 views

If a purely inductive circuit is started in presence of gravity, will the power source ever run out? [closed]

I have read that purely inductive circuits do no work. So if an Inductor with an AC source, coming from an inverter is set up, will the source of power ever run out due to work against gravity? This ...
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6answers
3k views

How does series circuit differ from parallel circuit?

Why does same current $I$ flow in the series circuit but it isn't the case with resistors in parallels?
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3answers
83 views

What is reactive power?

I am trying to understand what is reactive power. I have read that it has a relation with voltage, that is has a relation with the creation of a magnetic field in a motor, that it is coming and going ...
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0answers
46 views

Voltage and reactive power

Why are reactive power and voltage related? When the control system of a generator increases/decreases the current of the rotor, voltage and reactive power are increased/decreased.What is the relation ...
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2answers
68 views

How does current split in a parallel circuit? [closed]

I'm having trouble understanding why the current that goes through the 6 ohm resistor is 1A when the proportion of the parallel resistors is 2:1 from top to bottom. Could anyone explain how current ...
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1answer
47 views

Equivalent DC circuit with charged conductors

I am trying to find equivalent circuit for a circuit composed of interconnected capacitors when isolated pieces of conductor may carry nonzero electric charge, and I have been struggling with this ...
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3answers
69 views

Why fuse needs to be slightly more able to bear current than the appliance?

if I have a bulb with rated current of 4amps then why I need to connect an 5amps fuse?( which has slightly more ability to bear current.)
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1answer
45 views

power in an ac circuit - difference between in series and parallel

In AC-circuits, we have different kinds of power: active power $P$, reactive power $Q$ and apparent power $|S|$. Let's say we have a circuit with a resistor $R$ and an inductor $L$. My understanding ...
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1answer
81 views

How to find when an LRC circuit is critically damped mathematically, given a set of voltage/time data?

In an undergraduate-level experiment to approximate the resistance at which an LRC circuit system is critically damped, I found the resistance range within which the system is likely to be critically ...
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0answers
30 views

How Calculate the electric field into capacitor [closed]

Hello i have a problem with this exercise with capacitor, I have to calculate the electric field between the capacitor plates (neglecting the edge effects ), but I do not know how to do Text: A plate ...
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1answer
18 views

Does electron drift model apply to current in liquids

The electrons in a metallic conductor, tend to drift at abysmally slow speeds, but still a current is able to flow through it, because the net movement is in the direction of the applied emf. How is ...
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5answers
143 views

Resistance vs Power experiment - not linear relationship? [closed]

Ok, so I have been performing a lab experiment in class involving resistors. We were asked to set up 3x 47Ω resistors in 6 different combinations in a circuit with a 6V power supply. We also attached ...
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1answer
30 views

Is there any intuitive or mathematical explanation to this case regarding Kirchoff's second law?

I was trying to prove Kirchoff's Voltage law, which says that in a series circuit, $\Delta V_{battery} = \Delta V_1 + \Delta V_2 ... + \Delta V_n $, where n is a number of resistors. Before proving ...
0
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2answers
81 views

Current in parallel circuit and short circuits

I would like to ask a question which is partially addressed in this question: Current in Parallel Circuits Since the voltage in parallel is constant, why is it that when there is a short circuit, no ...
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1answer
37 views

Continuing on voltage drop across a resistor [closed]

What exact wire diameter allows approximately $6.25\cdot 10^{18}$ electrons to pass in 1 second? Will a thinner diameter or a wider diameter wire allow the same approximate number of electrons in a ...
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3answers
85 views

$P=VI$ and $P=V^2/R$ [duplicate]

How come equation a) $P=VI$ says if you double voltage, power is doubled while according to equation b) $P=V^2/R$ says power quadruples? Which one is correct?
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2answers
426 views

Ammeter range and shunt resistance

Its said that for an ammeter to give good reading, the full current in the circuit must pass through it. But if I am right, the ammeter is basically a galvanometer connected parallel to a very low ...
2
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2answers
84 views

Voltage Drop and Current Flow

Assume we have a source @100 DC volts in series with a 200 ohm resistor. According to Ohm's Law, current flow in 0.5 amps. Voltage drop across this resistor is 100 volts and equal to the source ...
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2answers
389 views

Derivation of capacitive reactance

Let $Q(t)$ be the charge stored in a capacitor $C$ in $t$ time for alternating current. Now, $$\displaystyle Q(t)=Q(0)+\int_{0}^{t}I(t)dt\\=Q(0)+\int_{0}^{t}I_oe^{j\omega t}dt\\=Q(0)+\frac{I_oe^{j\...
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1answer
40 views

How does a capacitor get charged while the charger circuit isn't closed? [closed]

a capacitor is a very known device in circuits that can be used as a short-time battery by charging it using another source, but how does it really get charged? if the plates of the capacitor don't ...
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1answer
97 views

Resistance D-C circuit [closed]

This question seems simple, but gives two plausable answers: On your first day at work as an electrical technician, you are asked to determine the resistance per meter of a long piece of wire. The ...
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3answers
93 views

How can the copper wire in an electricity generator provide an infinite number of electrons? [closed]

How can copper wire in an electricity generator produce an infinite number of electrons when the is a finite number orbiting each copper nucleus?
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1answer
652 views

Solving a circuit with Kirchoff/Ohms Law

Good evening, I haven't had physics since year 7 and now I need to use elementary things in university. Since I lack a lot of basics I am now trying my best to fill these holes. Currently I am stuck ...
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votes
2answers
197 views

If connecting an ammeter in parallel will cause short circuit, why won't connecting it in series does?

short circuit will happen when there is nearly no resistance in a wire, and when a high current almost infinite flowing through the wire, causing high temperature. But connected in series, an ...
2
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5answers
6k views

Difference between live and neutral wires

In domestic electrical circuits, there are 3 wires - live, earth and neutral. What is the difference between the live and neutral wires? As there is AC supply, it means that there are no fixed ...
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2answers
55 views

Can someone explain me these doubts regarding voltage in an intuitive way?

This is something I have been thinking for a while. At my level, I don't know much about electric fields. Now, I will be asking two questions: One for series circuit, and the other for parallel. ...
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2answers
78 views

Resistances connected in series

When resistances connected in series then why through each resistances the different potential difference occurs?
3
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4answers
3k views

Is a capacitor in an open circuit charged?

Say I have a circuit consisting of a battery, a wire, an open switch, and a capacitor. The circuit is open since the switch is open. My book says that the capacitor will only be charged when the ...
1
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3answers
544 views

How can a voltage across a capacitor be greater than the total voltage applied to the circuit?

I was reading about complex impedance and AC circuits, and I just came across a sentence on a website stating that the voltage across a capacitor can be greater than the applied voltage. How can this ...
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3answers
75 views

Why do we say that there is a voltage drop only when charge passes through a resistor? [closed]

This is a little confusing for me. I will just ask a few questions: First: Am I correct in saying that while traversing through the circuit, charge looses some electric potential(not energy) at ...
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0answers
58 views

Alternating current. Resultant force

I've just been wondering: In an alternating current, the direction of the current is constantly changing. This implies that the acceleration of the charge carriers is constantly changing (pos. neg. ...
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1answer
69 views

Why do we prefer using materials of high resistivity in laboratory instruments?

I know that :$$R=\rho\frac{l}{A}$$ where $R$ is the resistance of the wire, $\rho$ is its specific resistance (resistivity), $l$ is its length, and $A$ is the area of cross-section of the wire. Why ...
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1answer
64 views

Short circuit in superposition

I'm really confused about the concept of short circuits. I don't understand, why when you short those two voltage sources, 20 and 10 ohm resistors become parallel? What happens with 4, 12, 15 ohm ...
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1answer
48 views

Using superposition to find current

I'm given the following problem I'm a little bit confused about superposition problems when current flows through a voltage source but not the resistor. 1) When I looked at the solution for this ...
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3answers
12k views

Why connect cells in parallel?

Say there is a circuit with two 1.5V cells, and a 100 ohm resistor. If you connect two cells in series, then the total emf is 3V. And the current will be 3/100 = 0.03 A. (Using V = IR): If you have ...
2
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1answer
54 views

Equivalency of $Q$ Factor Definitions

The Q factor is defined (seemingly) as $$Q=2\pi\frac{\mathrm{energy \, \, stored}}{\mathrm{energy \, \,dissipated \, \, per \, \, cycle}}$$ however on Wikipedia is says that the Q factor can be ...
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0answers
37 views

Why is the force from an electric resistor linearly proportional to the drift velocity?

In a circuit, the potential difference across a resistor is given by Ohm's Law as V=IR. Since the potential difference is the loss of potential energy per charge and the force is -dU/dx, we get that $$...
0
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3answers
101 views

If current is same, is it correct to say that the speed of charge passing through a resistor is more than that of a normal wire?

It took me a long time to understand that current is constant throughout the circuit. And now I am stuck at one last thing: The speed of charge. Here is what I am thinking: Current is defined as ...
0
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2answers
34 views

Voltage across a resistors

When i was doing the practice problems, I found the following problem: I was able to solve for everything except for V4. When I looked at the solution manual,solution was as follows: Use KVL: V4 = ...
3
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1answer
81 views

How does the energy remain conserved in a transformer?

The induced voltage in the secondary coil of a transformer is given as $\frac { { N }_{ S } }{ { N }_{ P } } *{ V }_{ P }$ (where ${ N }_{ P}$ and ${ N }_{ S }$ are the number of turns in the primary ...
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2answers
61 views

Solving for node voltages

I have the following circuit and i need to solve Is, v1 and v2. First of all, I assumed that this problem will involve supernode principle since there is a voltage source between V1 and V2. Then, i ...