Questions tagged [electric-circuits]
An electronic system, with closed loop current flow, and relative electrical potentials present across electrical components.
4,423
questions
1
vote
0
answers
18
views
Why Faraday homopolar generator need brushes?
It is said that if one would attach a load physically to the rotating disc from center to rim no current would flow because both in the load wires and the disc itself currents would be generated in ...
0
votes
2
answers
20
views
Flow of electricity using two charged balls
Let us take a positively charged ball and a negatively charged ball and join them with a metal rod. Now if we connect one end of a wire with the positively charged one and the other end of the wire ...
- 265
-2
votes
0
answers
164
views
Question on current's path [closed]
Consider the following diagram. Let us say we wish to find the path which the current takes when we apply a potential difference across A and B.
Here each side of a square is a resistor of resistance $...
- 123
0
votes
2
answers
58
views
Confusion about energy transport in a circuit
I have some confusions about how to imagine energy flow in a circuit. Imagine for example just a simple circuit with a battery, two wires and a light bulb.
According to classical Electrodynamics the ...
- 225
-1
votes
0
answers
32
views
Finding unknown resistance in Wheatstone bridge [closed]
Here's a question of NEET:
A Wheatstone bridge is used to determine the value of unknown resistance X by adjusting the variable resistance Y as shown in the figure. For the most precise measurement ...
-2
votes
0
answers
15
views
What is meant by work done by batteries against the induced emf in the inductors? [closed]
I came across a question of jee advanced 2020 paper 2 question 17
- 1
-1
votes
0
answers
39
views
In a complex electric circuit of resistors connected to a cell then on changing the direction of cell, why the magnitude of current remains same?
I m struck in a question of an electric circuit ,while explaining the solution my physics teacher used a concept that he reversed the direction of cell in the circuit and told that the current ...
0
votes
1
answer
45
views
Capacitance and the battery connection
In the photo I added there is a question and its solution (given). It has been written at last(as I highlighted) that 'in order to get the minimum capacitance, dielectric should be removed and battery ...
0
votes
1
answer
26
views
What is "capacitive effect" in terms of battery research?
For example, the paper I am reading states that the current was "periodically interrupted without changing polarity" to "demonstrate that the peaking behavior is not due to a capacitive ...
12
votes
5
answers
3k
views
Why we use vector sum to calculate net potential in AC circuits?
My physics professor used vector sum to find net voltage at any instant in the following $RL$ circuit and said that it is equal to vector sum of phasor vector of potential drop across Resistor and ...
- 131
0
votes
2
answers
50
views
Why electric charge does not gain net energy in closed circuit?
In a text book, when they calculate power dissipated in a closed circuit, they use circuit with a battery and one resistor. Idealized positive charge travels from +...
- 245
0
votes
2
answers
30
views
Discharging a capacitor conceptual question
When a capacitor is discharging, why is the potential difference across it at any time $t$ equal to that of the resistor? Do the two potential difference's not have to add up to the EMF of the supply ...
- 197
0
votes
0
answers
26
views
Effects on net Electric Potential with the insertion of a dielectric into a network of two capacitors in series?
Suppose you have a circuit with two capacitors of equal capacitance C, C1 and C2 that remain connected to a battery at all times. A dielectric is then fully inserted between the plates of C1. What, if ...
0
votes
0
answers
38
views
Does $P=VI$ contradict $V=IR$? [duplicate]
Imagine there's a dam generating power (P) that needs to be transported 100km away. Engineer Pedro suggests increasing the voltage to reduce current acording to P=VI, while Engineer Juan suggests ...
1
vote
1
answer
48
views
Forbidden capacitance in LC circuit connected to AC source [closed]
While solving problems on AC circuits, I came across one that had a circuit connection as shown below.
The question was to find the value of "the capacitance that can never be used in this ...
- 13
-1
votes
2
answers
51
views
How do the nodes affect the circuit?
I am tasked to simplify this circuit to one source and one resistor, which is equivalent to the original but obviously easier to solve.
My problem is the fact, that I don't know how the nodes A and B ...
- 1
0
votes
0
answers
56
views
Why there is no EMF induced in this circuit
Why there is no current flow in this circuit?
On this diagram, the copper wires are long and extend far beyond the magnetic field range and they rotate with multimeter or BT transmitter, magnet is ...
6
votes
0
answers
40
views
Is my reasoning about $ε = iR$ correct, where $ε$ denotes induced emf, $i$ denotes induced current, and $R$ is resistance of loop [closed]
I came up with the formula, $ε = iR$, where $ε$, $i$ and $R$ denotes induced emf, induced current and resistance of loop respectively. I did the following reasoning to prove this formula, am i right?
- 69
0
votes
0
answers
16
views
Transformer primary Voltage and emf relation
This is a conceptual query. So if possible kindly answer more conceptually.
Consider an ideal transformer. We have a input voltage Vp, and voltage in secondary coil as Vs.
now, we write emf equations,...
0
votes
4
answers
54
views
Rigorously showing that steady state will be reached in simple DC circuits [closed]
Consider a simple DC circuit in which we have a source of emf connected to some resistance $R$.
Now all the books I have consulted give me heuristic arguments as to why a steady state will soon be ...
- 77
2
votes
3
answers
277
views
Validity of Ohm's to non-steady currents
My textbook Griffiths electrodynamics says the current density at a point in a material is given by $j=\sigma f$, where '$\sigma$' is the conductivity and $f$ is the force per unit charge at that ...
- 77
0
votes
2
answers
54
views
Reference point of potential in case of a battery
When we define electric potential of a charge,we need to take a charged body as a reference and then we bring the test charge to calculate the electric potential. Now,electric potential energy is ...
- 265
8
votes
1
answer
45
views
Why In the following $RL$ circuit, the connection to $b$ must actually be made an instant before the connection to $a$ Is broken? [duplicate]
In Resnick halliday, student 10th edition page - 795. In the topic current decay in RL circuit, the following statement is used, the connection to b must actually be made an instant before the ...
- 83
0
votes
0
answers
43
views
Is this capacitor arrangement parallel or in series? [duplicate]
I came across this situation :
A 2 μF capacitor is charged by a battery and after that battery is removed and an 8 μF capacitor is connected to the charged 2 μF capacitor.
Now charge would flow from 2 ...
0
votes
1
answer
49
views
How exactly does an inductor behave in a circuit after reaching its steady state?
I was solving this question in my coursebook and was not able to understand it conceptually. Though I did understand the mathematical approach to it.
Now I understand that when the rod is given an ...
- 51
0
votes
3
answers
33
views
Does current develops instantaneously as we apply potential difference?
I had this doubt from the starting since I studied current electricity, that if we apply a potential diff. Across a resistor, does the current flow instantaneously, if it does then the communication ...
- 31
1
vote
0
answers
70
views
Physics diagram to electrical schematic [closed]
I am asking this question on behalf of user furious.neutrino. I asked this question at Electrical Engineering Stack Exchange, but it has not received a reply, so I am duplicating it here. I think the ...
- 2,804
4
votes
4
answers
499
views
Load Lines and Characteristic Curves
While studying electronic circuits involving diodes, I came across the concept of characteristic curve, which relates the voltage drop in a diode with the current through it. However, I was also ...
- 364
0
votes
1
answer
46
views
How to calculate the total resistance? [closed]
So I am new to physics and I am trying to solve the total resistance of this circuit. My question is: because there is a battery in the same branch as R2 and a Capacitor in the same branch as R3, when ...
0
votes
1
answer
60
views
About electricity flow through a diode
I have read answer of Vintage in 11 July 2011 on Krzysztof Lewko's question
Why can electricity flow only in one direction through a diode?
I appreciate very much this answer and i vote as "this ...
- 11
0
votes
1
answer
42
views
Simple $RC$ circuits
I have a $RC$ circuit with a capacitor (capacitance$=C$) uncharged initially and resistor (resistance$=R$) in series with the battery of EMF $E$. Assume its internal resistance to be negligible.
Now ...
0
votes
2
answers
45
views
Electrical field in a circuit
This is a picture I found online:
I have two questions about this.
How do we know that over the power source and over the resistor, the electrical field is parallell to the power source or resistor. ...
- 189
3
votes
1
answer
123
views
What is the electric field around an inductor?
This question comes from this Walter Lewin video at 35:00 where he says "I'm going to confuse you even more" (and I suppose he somewhat succeeded). Walter Lewin claims there is an electric ...
- 7,904
1
vote
2
answers
70
views
Why doesn't the coil of a DC motor accelerate infinitely?
In a DC motor, when current is passed through the coil in a DC upon contact with the brush, it seems to be moving at a constant speed. But after half a rotation, a current is passed through the coil ...
0
votes
2
answers
35
views
On transition of electrons between energy levels / potentials
In an electric circuit, electron flows from the negative terminal of a voltage source to the positive terminal, which in turn, gives us the the conventional direction of electric current. So, the ...
- 49
0
votes
1
answer
50
views
(High School Level) How to calculate effective resistance on parallel circuits? [closed]
I was doing an AQA Physics Alevel (UK Syllabus) past paper and I came across this past paper question:
It asks me to 'calculate effective resistance between P and Q'. I had a few attemps in trying to ...
0
votes
1
answer
30
views
If the current in a conductor doubles, how would the amount of heat evolved change? [closed]
So I came across this question in a textbook, and it says
“If the current in a conductor increases to twice the original magnitude, the amount of heat it releases per second would increase by how ...
8
votes
2
answers
1k
views
Physical Cause of Reactance of Inductors and Capacitors
We know that a capacitor and an inductor both offer some opposition to the flow of current through an AC circuit and their reactance is a measure of the amount of Ohmic opposition due to these circuit ...
- 271
2
votes
2
answers
50
views
Does KVL don't hold in pn junction reverse bias?
Does KVL hold in pn junction reverse bias because any reference about semiconductor physics provide that figure
if we apply KVL around the loop won't be zero it will be equal to $V_{bi}$
then how KVL ...
- 577
0
votes
1
answer
105
views
Showing that the power is $P=UI$ using the Poynting vector
If I have a circuit with a resistor I want to show that the power delivered to the resistor is UI using Poynting vector. To do this I must integrate the pointing vector over a surface that contains ...
- 189
0
votes
0
answers
19
views
Effect of projectile movement inside the coil launcher
I'm simulating a simple coil launcher system where there is a round coil , a capacitor and a round projectile which at first is placed at the start of the coil.
so the whole circuit is a simple RLC ...
2
votes
0
answers
39
views
What if two plates charged with different charges are placed face to face?
I'm asking this question because I can't solve it even if I ask a lot of smart people. (Please understand that I don't speak smoothly because I use a translator. I'm korean student..)
In the next ...
- 21
-1
votes
2
answers
114
views
How high voltage and low current is beneficial for power transmission which is contradicting $V²/R$? [duplicate]
I have read that during power transmission high voltage is used because for same power output, high voltage produce low current and due to low current, according to I²R, heat loss through cables are ...
- 123
0
votes
1
answer
53
views
Electrical and Electronic circuits simulation using Maxwell's equations
How can the Maxwell equations be used for developing exact mathematical model of electrical and electronic circuits?
- 11
1
vote
3
answers
70
views
Why is the emf of the battery which is being charged included for the current flow?
When a battery is being charged, let's say it has an emf $\mathcal{E}$ and internal resistance $r$. At first it's completely drained, and we use a battery to charge it back, and lets say the emf of ...
- 365
0
votes
1
answer
37
views
Why current density is defined?
I feel that the reason to define thing like current density is that we want to use the directional nature of the current like a vector quantity and since electric current is not a vector so we define ...
- 131
32
votes
9
answers
5k
views
What is the most appropriate mathematical theory for electrical circuits?
What exactly are electrical circuits as mathematical objects?
It seems quite intuitive to me, that they are geometric realization of some graph with some additional structure.
Another thing I notice ...
- 7,793
0
votes
1
answer
24
views
How can a current carrying conductor have $0$ electric field and be equipotential
Consider a circuit with some resistance $R$ attached somewhere across a battery. The connection is made using some ideal conducting wires with $0$ resistance. Now, say some current $I$ flows through ...
- 271
0
votes
0
answers
21
views
Electric Resistance In a conductor [duplicate]
If Resistance offer obstruction to the flow of current then why current don't reduce
Any response would be apriciated
- 31
0
votes
0
answers
12
views
Skin Effect and Eddy Currents Question
Wikipedia has the following image explaining the skin effect:
With the caption:
Cause of skin effect. A current $I$ flowing through a conductor induces a magnetic field $H$. If the current increases, ...
- 2,143