Questions tagged [electric-circuits]

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

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2
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1answer
45 views

How does an inductor work?

I wonder how does an inductor resist the changing magnetic field, all the information I searched said that there is no current in the moment when the inductor is connected to the battery. This is ...
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1answer
29 views

Relationship between voltage and distance in electrodynamics

Just to clarify, I’m just now learning about physics for the first time, and ran into some confusion about how voltage works. In electrostatics, I learned that voltage is dependent on distance based ...
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1answer
38 views

How would this symmetry argument in circuits be proved?

My teacher had taught us how to solve circuit problems using symmetry. One of the symmetry axis he had called "transverse symmetry" which the axis will be perpendicular to the line joining ...
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0answers
22 views

Resistance between two points in a circle [closed]

so the question is asking for a resistance between two points on a circle and that the circle is copper wire so the resistivity of copper wire is suppose to be used. the givens are that the radius =...
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1answer
27 views

Maximum Voltage using two capacitors and a battery [closed]

What maximum potential difference can you obtain with the help of a battery of voltage $V$ and two capacitors of capacitances $C_1$ and $C_2$? ($C_2>C_1$) The answer given is $2V(C_1+3C_2)/(C_1+C_2)...
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1answer
32 views

What do we mean “exactly” by effective capacitance?

For series combination, effective resistance means replace all the resistors by a single resistor in which current flowing is the same. For parallel, it means replace all the resistors by a single ...
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2answers
27 views

In a resistor capacitor circuit, when capacitor is discharging, do the free electrons in the conducting wires or resistor move?

In normal battery resistor circuits, battery doesn't store any charge, its basically the free electrons of resistors /conducting wire that moves in a circuit. But in discharging of capacitor, charge ...
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0answers
16 views

Determine the change of charge in both capacitors

I have the following circuit The switch has been open for a long time, and both capacitors are fully charged. After that, the switch is closed and the circuit is broken. I need to determine the ...
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1answer
38 views

Why does a parallel plate capacitor discharge itself?

If in a RC circuit with no battery, there is a parallel plate capacitor having charge $Q$ and a resistor of resistance $R$. To satisfy Kirchhoff's voltage law (KVL) current must flow from the ...
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0answers
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Can any two elements in the circuit be labelled as series or parallel? If not, how can I find voltages and currents? [migrated]

This is a voltage amplifier circuit I want to build and curious about the series parallel connections so to understand the working of each element. My understanding of the circuit is: 6.8k ohm ...
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2answers
62 views

Some questions about the capacitor [closed]

Why can the parallel plate capacitor not be charged with unlimited charges? Since the zero resistance wire do not have the electric field inside, and the two parallel metal plates with an equal ...
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0answers
24 views

A problem about node voltage method and circuit analysis [closed]

Consider that the capacitor is open circuit and the switch is closed. What I need to find is $v_o(t)$. I tried to solve this problem in 2 ways: Transforming all voltage sources to current sources and ...
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4answers
432 views

Why is there no electric field in the ideal wire?

Why is there an electric field only inside the resistor in the circuit (assuming that the wire has no resistance)? If there is no electric field inside the wire, why does the electron move to the ...
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0answers
19 views

Circuit, Wye-Delta transformation(?) [duplicate]

I'm new to circuit analysis and I'm stuck on this question. My question is: What could I do, or what steps should I take to solve this kind of circuit? What the question asks is basically the current ...
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0answers
35 views

Please help me find equivalent resistance between these two marked points [duplicate]

It is my self created question and hence answer to this question is not known . Please help me find resistance between A and B in the following circuit . Thanks I know i have previously asked this ...
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0answers
49 views

Please find the equivalent resistance between A and B in this circuit [closed]

It is my self created question and hence answer to this question is not known . Please help me find resistance between A and B in the following circuit as i am facing a little difficulty in ...
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1answer
34 views

Determining impedance of the circuit from peak values of current and voltage

Does the following equation given in my book $$i_m = \frac{V_m}{Z}$$ where $i_m$ and $V_m$ are peak values of current and total voltage $V_m = \sqrt{(V_L-V_C)^2+V_R^2}$ and $Z$ is impedance, hold for ...
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1answer
19 views

Relation between initial current and current amplitude in $RLC$ circuits

Let $\phi$ be the so called phase-angle, which measures how much the voltage $V(t)$ leads the current $i(t)$ in a $RLC$ circuit. How would you justify the relation $$i(t=0)=i_m\cos\phi$$ where $i_m$ ...
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14answers
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How do electrical devices limit the current flow from a socket?

How does a home appliance limit the amount of current that flows through it? Are there some resistors set up in series in order to cut down the current flow before it actually reaches the device? ...
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0answers
19 views

Different live and neutral wire terminals on different plugs [closed]

Here is the problem, one of the power cable(1st pic) came with XPG core reactor power supply for my computer, and the other UK plug(2nd pic) is of my Samsung LCD. And as you people can see, both have ...
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7answers
422 views

How does current flow in a circuit with a capacitor?

When a capacitor is connected to a battery, current starts flowing in a circuit which charges the capacitor until the voltage between plates becomes equal to the voltage of the battery. Since between ...
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3answers
129 views

Is potential difference $0$ across a $0$ resistance wire but of non-uniform cross section area?

I know that for a $0 \;\Omega$ wire of uniform cross sectional area, the potential difference across its ends is zero as no electric field is required to move charge with constant velocity (necessary ...
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2answers
59 views

Is there a small spark every time a switch is closed to engage a circuit?

Suppose we have a simple circuit with a resistor $R$ connected to a DC voltage source $V_{\text{batt}}$. The circuit can be enabled or disabled by a switch. The dielectric breakdown of air is $E_{\...
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0answers
37 views

Energy loss due to changing capacitance [closed]

I was able to solve first two parts of the question. But after solving third part (energy loss to be precise), I felt conflicted. I calculated that Uinitial = 0.0162 J and Ufinal = 0.0162 J So then ...
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1answer
24 views

Second-Order Transient Analysis Question [closed]

I am currently stuck on a problem and am unsure on how to solve it. The problem can be seen at the bottom of the post. I know that for second-order circuits we have to figure out the dampening using α ...
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1answer
60 views

Is drift velocity of electrons 0 in 0 resistance wire?

In a 0 resistance wire electric field inside the wire is 0 as there is not potential difference . Which means when charges once start to flow ,no external force acts on them and therefore no electric ...
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0answers
18 views

Capacitive circuits with two or more potential differences

Just I was curious on this question that I like very much. Here I add my image create with my fingers. Recently I have been looking at the Physics textbooks that I have, including that of the ...
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1answer
32 views

If there's a capacitor fully charged and the other isn't fully charged a and they are in parallel are the tension in the two capacitors equal? [closed]

V is the final tension of the second capacitor, but the other one isn't fully charged and both of them are in parallel, are the tension of the two capacitors equal?
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0answers
21 views

What is the Initial tension in a equivalent capacitor? [closed]

In the equivalent capacitor of this association, what's the initial tension of the equivalent capacitor? $V_0$ is the initial tension.
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1answer
45 views

Is this a correct way to think about 2 batteries connected in series?

Ok in this thread I asked about the potential difference between two separate batteries. My thought was, that if a voltage of a battery is all about potential difference between the two terminals, ...
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7answers
226 views
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Why do we treat the whole capacitor as if it would be a single conductor?

I am a high school and I am very confused in redistribution of charges when we connect 2 capacitors, my problems are: why are we treating the whole capacitor as if it would be a single conductor and ...
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1answer
54 views

Is there voltage across the negative terminals of 2 batteries?

I understand that voltage is all about potential difference between two points, and that we can't really determine an "absolute voltage" of any point, only with respect to some arbitrarily ...
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2answers
24 views

How does a battery bring conductors out of electrostatic condition?

What does a battery exactly do to the conductors (eg metals)? How does it develop a field inside a conductor? On applying external field to the conductors (* I think that there will be a potential ...
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4answers
59 views

Why is voltage equal across the resistors connected in parallel? [duplicate]

Say I have a circuit and three resistors connected on parallel. Then if I want to calculate equivalent resistance i use the ohms law(V=IR). Call the three resistors R1,R2,R3 and current passing ...
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1answer
59 views

What exactly causes resistance?

According to Ohm's Law, $V=IR$. Here $R$ denotes the resistance. It's the way I was introduced resistance. The definition is not convincing me. First of all I don't understand what causes resistance? ...
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2answers
39 views

Meaning of Voltage in Ohm's Law

Ohm's Law states $$V=IR$$ where $V$ is te voltage, $I$ the current and $R$ the resistance. Since voltage is defined in terms of electric potential, and electric potential defined in terms of electric ...
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0answers
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Is the supply voltage and the induced voltage same in a loaded (practical) transformer?

For a loaded transformer not considering the winding resistances and inductance, induced voltage = Applied/terminal voltage in primary and secondary sides. But given a practical transformer (with ...
8
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5answers
2k views

How does the speed of electricity become the same as the speed of light?

"The field due to the battery sets up a surface charge in the wire. The surface charge is negative near the negative pole of the battery, and positive near the positive terminal, and varies more ...
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1answer
84 views

Why do two approaches to this capacitors problem give two answers? [duplicate]

I came across a capacitors problem that seemed to be very simple, but I can't figure reasoning as to why two approaches to the problem yield two different answers. One of them is wrong, but I can't ...
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5answers
870 views

Calculating equivalent resistance [closed]

In the given circuit, find the equivalent resistance between points A and B. I solved this question in two different ways, out of which one gave the correct answer. The correct method is the most ...
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3answers
53 views

What does an $x$ Watt bulb actually means?

Let's say I have a 11W bulb in my home, connected to a 220V power supply. What exactly does it mean that this bulb is 11W? As far as I know, the Wattage is determined by the formula $W = V * I$, so it ...
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1answer
49 views

Which lamp(s) will glow? [closed]

I thought it would be through lamp 1 and 3 because the electrons can go through the circuit between lamp 2 and 3, then through lamp 3 then through the circuit between 2 and 3 again and finally down to ...
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1answer
68 views

Potentiometer related question [closed]

Sorry, I am posting a assignment question but I found no other option. Figure shows a potentiometer circuit for comparison of two resistances. The balance point with a standard resistor R=10.0Ω is ...
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2answers
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Does charge develop on the surface of a current carrying wire?

Well i think electric field must exist outside a current carrying conducting wire. Because if you consider a simple circuit with a resistor and a battery potential difference is created across the ...
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3answers
2k views

How does grounding work?

This is a simple circuit that has been grounded. My question is, after reaching point $A$ will the current $I$ reach the negative terminal of the battery or will it go to the earth?
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1answer
47 views

What will be the equivalent EMF if we connect cells with 0 internal resistance in parallel?

Well we have a formula for calculating equivalent EMF of n cells with EMF $E_1,E_2,E_3,....E_n$ and internal resistances $r_1,r_2,r_3,....r_n$ as $$E= ({E_1/r_1 + E_2/r_2 + E_3/r_3)}/({1/r_1 + 1/r_2 + ...
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1answer
103 views

Why Electric field is same in a cross section of wire even if we change its thickness? [closed]

how does E remains same for the increased thickness. E is determined by field lines, if there is fixed number of field lines coming in then how it gets increased by increasing thickness of wire? To ...
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2answers
36 views

Why does potential difference cause current?

I'm doing a physics course in my final year of high school, and I'm finding electricity and magnetism conceptually hard. Everywhere online says that potential difference is the difference between ...
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2answers
48 views

Electric shock?

If I spin a magnet really fast, and put my finger near it, i get no electric shock. However if i place a wire near that wire it will induce an emf across the wire, if i touch it, will i get a shock? ...
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3answers
58 views

Why doesn't current flow through an open branch?

I know that current doesn't flow through open branch because current can't flow through air due to its high resistance .But i was thinking , what's the problem if current flows through an open wire (...

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