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

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Even when the drift velocity of the electrons is very small, how is current in the circuit established immediately?

So I have this question in my textbook and Ive also got it in my test. Ive written a wrong answer. My friend wrote the drift velocities of each particle add up and he got full marks. Is it right? Can ...
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1answer
29 views

Earthing, neutral and Earth's conductivity

Ok so this is gonna be a lot of mini-questions. What exactly is the neutral wire? How does earth conduct electricity for a live AC mains even though its just dirt and stones (it should be an ...
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1answer
42 views

What happens when an AC source is connected to a capacitor and a LED?

When a DC source is connected to a capacitor and a LED, and the voltage is removed when capacitor is charged, the capacitor supplies current to it for some time. What happens if this DC source is ...
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1answer
34 views

Laser as an optical oscillator

How can Laser can be compared to a positive feedback amplifier? Does the two conditions for oscillator holds good for lasers too.
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1answer
22 views

holes in an electronic circuit [on hold]

Many times, by looking at electronics circuits I noticed that they have like small holes printed in yhem. The question I want to ask is, what s the purpose of these holes?
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1answer
40 views

Resistor in series

We know that when a resistor is connected in series , the current flowing through that resistor will be constant.But how do we use a resistor to limit the current flowing through a circuit ,when ...
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2answers
26 views

Elementary derivation of $P = UI$ starting from the definition of voltage as work done per unit charge

Consider the following elementary derivation of the formula $P = VI$ for Joule heating of a resistor $R$ for the dissipated power $P$ where the voltage over the resistor is $V$ and the current $I$. ...
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1answer
54 views

Proof of Kirchoff's second law

There are 2 approaches I have stumbled to prove Kirchhoff's second law: Derive it from the conservation of energy. You can derive that from "integral of E*ds = 0". Can you show me a full or at ...
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0answers
52 views

Minus sign in analyzing RC with changing emf circuit?

I'm learning electromagnetism from Purcell's book. He say that if we have the following circuit: $$-\frac QC + RI = \mathcal E_0\cos\omega t~,\quad I = -\frac{\mathrm dQ}{\mathrm dt} $$ The ...
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1answer
38 views

Possible reasons of electrocution in a good earthed appliance during sudden power off [on hold]

I was working in a industry. When I was using a machine, I felt slight electrical shock at the exact moment when the power supply went off. The machine is properly earthed. In spite of that I got ...
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0answers
19 views

Equivalent Resistance in electrical circuit [closed]

4 resistances of value 1 ohm each forms a quadrilateral.Each diagonals of a quadrilateral also consists of 2 resistors of value 1 ohm each.What will be the value equivalent resistance of the circuit ...
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0answers
16 views

What's the back EMF on a spherical conductor suddenly surrounded by a negatively charged shell?

Suppose one has a spherical conductor of radius r. Suppose it is suddenly surrounded by a negatively charged shell. The conductor will rush to balance out the voltage. However, this changing current ...
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19 views

When happens to the current during reversed biased?

The main working function of a half wave rectifier is to convert AC current to DC. My problem is to understand during the negative cycle. The above picture is time versus current. We can see easily ...
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18 views

What transformation produces this kind of dual circuit?

What relates the following table of equivalences? Series $ V_{ac} = V_{ab} + V_{bc} $ Parallel $ I_{ac} = I_{ab} + I_{bc} $ Resistor $ V = \mathrm{R} I $ Conductor (the same) $ I = \mathrm{R}^{-1} ...
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0answers
27 views

my question is from current electricity and resistance class 12? [closed]

in the network given in the figure, determine potential difference across the capacitor?
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0answers
22 views

About voltage sources in series [closed]

What is the reason of connecting batteries in series to obtain a higher voltage?
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1answer
48 views

Why Thevenin's theorem is being violated?

in the given picture we need to find the current flowing through the 3 ohm resistor. Applying KVL we can find the current as 4 amps but if we thevenise the circuit at terminal a-b then the current we ...
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1answer
37 views

Behavior of coil and resistance in DC circuit [closed]

I have a simple circuit of a coil parallel to a resistance and then in series with another resistance. I wanted to understand the behavior of this circuit so I ran a simulation, and what I noticed is ...
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1answer
16 views

Is peak voltage or peak current kept constant when we change resistance in an AC circuit?

I found online that Ohm's law still applies to an AC circuit and that $V_{peak} = RI_{peak}$. However, I can't seem to find anywhere weather an AC source will : Act as a voltage source and keep its ...
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0answers
65 views

Circuit theory paradox - Unexpected results [closed]

I recently studied capacitors and found out that there is something called 'ideal circuit paradox'. Searching Google I found that one can cannot find the potential difference between two points in a ...
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2answers
46 views

Why is there only a drop in potential energy when charges flow through a resistor?

First, I read that if you move a charge (say a positive charge) against an electric field, its electric potential energy increases because you're doing work to move the charge to that position. I also ...
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1answer
43 views

Different voltage drops depending on the path

I was working through a problem in electromagnetic induction when I discovered that I have a fundamental ignorance of some sort that is puzzling me. Consider a circular wire, at rest, perpendicular ...
2
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1answer
32 views

Is it possible to measure the resistivity of something using A.C. Current and a capacitor?

I've read that A.C. current "passes" through a capacitor. Is it possible to use this and measure the resistivity of the medium between the plates? Any sources or links would be appreciated.
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1answer
19 views

Armature of electric bell [closed]

I want to know that why is the armature of the electric bell made up of soft iron ? I googled this out and everywhere it was written that it is because of its propert to aquire electromagnetism but I ...
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1answer
47 views

Resistor homework assignment: 7 resistors with connected triangles [closed]

I am a lost in how to solve this problem, since I don't how where to start. The questions doesn't inform any voltage or current, asking only the equivalent resistance of the circuit. All resistors ...
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0answers
32 views

Cells in parallel

Two cells of EMF 1.5V and 2.0V having internal resistances 0.2ohm and 0.3 ohm respectively are connected in parallel. Calculate the internal resistance of the equivalent cell.
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52 views

Resistance Distance in large electrical networks

I am not tremendously familiar with electrical circuits (I have some memories, but too long ago) and now I have come accross a problem where I need to compute the resistance distance in a graph. So, ...
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3answers
21 views

Difference in directions of charge and current.?

I just dont understand that why does charge flow in a different direction as that if current when current is the rate of flow of charge.
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28 views

Why is it that for a source of emf, current flows from lower to higher potential?

I'm quite confused about this actually! In fact, I had always thought current flows from a region of higher potential to a lower one. Does it have anything to do with the fact that it's a source of ...
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1answer
38 views

How does voltage produce current?

I am studying electric current and i dont understand how does voltage(potential difference )produce current? PS : I am a 10th grade student so please avoid complicated terminologies.
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0answers
17 views

Find voltage at a point on infinite ladder of resistances [duplicate]

Find voltage at point C. What I have tried. Find the effective ladder of resistances. Which comes out to be R(sqrt.3 - 1) Then find the current. 48/Reff Then split the current and find current ...
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1answer
25 views

Current flow in absence of a potential difference [closed]

What if at two different points in a wire connected to a system of capacitors and resistors, the electric potential is equal. Will the current flow? There is also a battery connected.
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3answers
43 views

Ohm's law and an ideal voltmeter

In an ideal voltmeter there is infinite resistance so because of which no current is flowing through it and the voltage reading is not affected. The ohm's law stated that V = I * R In an ideal ...
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0answers
23 views

PARALLEL COMBINATION OF SUPERCONDUCTORS AND RESISTORS [duplicate]

........................please reply to the question above in the picture. I have tried a lot and have thought about it for a long time. Please help me and answer in simple words. AND I REQUEST NOT ...
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2answers
60 views

Are these capacitors parallel or in series?

I am a bit confused. The authors say these conductors are parallel when the switch is on. But to me it looks like they are in series since the handle is insulating. How can you explain that they are ...
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0answers
35 views

Determine potential function given initial conditions?

Assuming a radially symmetric circular disk (let's say r=1). Given two simple initial conditions: Potential at the centre is 4 V Potential at the edges is 0 V How would I determine the potential ...
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3answers
38 views

Finding equivalent capacitance between A and B, [closed]

Following is the question, asked is to find equivalent capacitance between A and B. I've tried couple of times and getting 7/3 micro farad as the answer while the correct answer is 8/3 micro farads. ...
1
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1answer
51 views

Bulbs in parallel/series (very basic) [closed]

I need some help understanding very basic circuit concepts, specifically for the question in the image below. So from what I know is that in a series setup: voltage is divided over the components, ...
3
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1answer
124 views

What does a voltmeter actually measure?

For time varying fields (even quasistatic ones) the electric field is given by $${\bf E} = - \nabla \Phi - \frac{\partial {\bf A}}{\partial t}$$ So what does a voltmeter measure? Does it measure a ...
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0answers
12 views

Charges on outer faces of parallel plate capcitor

Can there be charges on outer charges of a parallel plate capacitor if both the plates are initially charged by different amount and then connected with a battery.
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0answers
27 views

Question about notation in a simple circuit [closed]

I was given this circuit in an Electricity & Magnetism course. On the far left, is that a current source providing 2A? It seems to be but I'm not 100% sure.
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1answer
24 views

Mechanism by which a capacitor is charged, using surface charges

I want to gain a deeper understanding as to how a capacitor actually gets charged. Consider a situation in which an uncharged parallel plate capacitor is connected to a battery using two wires. I ...
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1answer
34 views

Is a real voltaic cell always schematically equivalent to an ideal battery and a resistor?

In the diagram I have attached, the top circuit is the schematic equivalent I am trying to use to model the middle circuit which uses real voltaic cells (that have internal resistance). I am not sure ...
4
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4answers
64 views

Current in inductor just after switch is closed

I have read that the current in an inductor resistor circuit just after closing the switch is zero. This is derived by finding the differential equation in terms of current by using KVL. Is this true ...
0
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1answer
64 views

Can we “use” a capacitor while simultaneously charging it?

I know that capacitors can be charged to work like a battery . But I wanted to know whether we can charge a capacitor while it is in use ( given that the current supplied to it is more than what it ...
-1
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2answers
61 views

What is the reasoning behind calculating the resistance between two points on a square resistor circuit? [closed]

Here, the question asks me to work out the resistance between X and Y. The answer is 1.2 ohms. In a normal circuit, the resistance between two points is simply whatever resistor value(s) is between ...