Questions tagged [electrical-resistance]

The tag applies to electrical resistance and resistors. DO NOT USE THIS TAG for non-electrical resistance.

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26 views

Power dissipated by a resistor with a variable intensity

Let's consider an RC circuit with a current generator (we study in French so I don't know if the terminology is right, but a current generator produces a constant voltage and a variable intensity) ...
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1answer
132 views

Equivalent resistance for a complex circuit [closed]

The problem is to find a equivalent resistance for the system below (resistance are all same). I tied a mixture between the Kennely theorem and the laws of Kirchoff's, but i didn't find an optimal ...
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42 views

Potentiometer at balance point

In the first circuit below, the potentiometer is at balance point and we know that $V_A = V_C$; and $V_J = V_D$. In this situation, no current flows through the secondary circuit If we take this same ...
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61 views

Potential divider with voltmeter

Here are two circuits diagram simulated in Falstad. The voltmeter on the left measures the potential difference across the $8 Ω$ resistor. $6V$ at $P_1$ and $2V$ at $P_2$, therefore the Potential ...
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4answers
186 views

How to simplify this complex circuit?

I am new to circuit solving and I tried to simplify this circuit, but I am unable to do so. I can't figure out which resistances are in series and which resistances are in parallel. Do I have to use ...
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2answers
48 views

I'm confused on how current will flow in this system

I'm working with the following circuit: So, I thought that it might be a good idea to work with each mesh separetely. And then I did the following: But i'm really not sure if this is the correct ...
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3answers
137 views

Current vs voltage in high voltage transmission lines

I know this question has been answered many times, but sadly I'm still not quite sure I get it. Here's my interpretation, please correct me at any point: We have some source. There's various ways to ...
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2answers
46 views

How to determine the time taken by a cell to finish?

I have connected 2 cells one to one bulb another to 2 bulbs ,which would finish faster (it is a series circuit)? I have thought of two solutions:- Method 1: The cell connected with one bulb would ...
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1answer
68 views

What does it mean to apply a voltage bias on a superconductor when $V = IR$ and $R = 0$ for a superconductor?

I have been reading papers about superconducting nanowire single photon detectors, and in them the voltage bias the superconductor to close to $T_c$ so that a photon has enough energy to break the ...
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2answers
71 views

Trying to understand the concept of resistance

I am a software developer trying to teach myself some basic concepts of how electromagnetism works. At high school we were taught about electricity in all kinds of metaphors that, I realize now, ...
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59 views

Can a vacuum act as a good electrical insulator?

Assume two positively charged plates have voltages $V_1$ and $V_2$ and are separated by a distance $d$. Between the plates, there is a strong vacuum (not a perfect vacuum because that's practically ...
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59 views

Alternating current net impedance

I am trying to find net impedance using complex numbers using $\frac{Z_1 Z_2}{Z_1+Z_2}$ where $Z_1=R_1-X_C$ and $Z_2=R_2+X_L$. I am confused why this formula is valid here since it is for parallel ...
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22 views

Second-order equation for the resistance of a filament lamp

I am trying to determine the initial resistance $ R_0 $ of a tungsten filament in a filament lamp, by quadratic approximation of the resistance $R(T) = R_0[1 + \alpha*T + \beta*T^2]$ but I can't find ...
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34 views

Relative Amplitude: Current at full brightness [closed]

What is the relative amplitude of the flow in the filament of a miniature lamp the instant power is applied in comparison with the current at full brightness? a. High b. Low c. The current is the same ...
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113 views

A problem with the path of least resistance

I have a question about short circuits that I haven't been able to solve. From this we know: The total voltage V is constant, and the total current I is inversely proportional to the total resistance ...
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1answer
77 views

Why doesn't this formula given by my book about cells being connected in parallel work?

Derivation: Suppose, there is $m$ number of cells that are connected in parallel, each of whose emf is $E$ and internal resistance is $r$. An external resistance R is also connected with the ...
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99 views

Reverse $\displaystyle v(t)=R\,i(t)+L\,\frac{di(t)}{dt}+\frac{1}{C}\,\int_0^ti(\tau)\,d\tau$ as function of current $i(t)$?

Consider the electrical circuit equation written as $$v(t)=R\,i(t)+L\,\frac{di(t)}{dt}+\frac{1}{C}\,\int_0^ti(\tau)\,d\tau \tag{1}$$ where $v(t)$ is electrical potential, $i(t)$ is current, $R$ is ...
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115 views

Can grounding wrist prevent electrical shock?

Today while repairing some electronics and wearing anti-static wristband like on picture below I got thinking - in theory, would it be possible to avoid shock while working on mains by grounding ...
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What exactly is being alluded to here with regards to the atomic lattice and electron flow? [duplicate]

I am currently studying the textbook Learning the Art of Electronics: A Hands-On Lab Course by Thomas C. Hayes, with the assistance of Paul Horowitz. Section 1N.2 Three laws says the following: Why ...
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63 views

Why won't all voltage be used up on first resistor in series?

tldr: I am having trouble conceptually understanding voltage between resistors in series, even though I know how to calculate it using Ohm's law. How do the electrons "know" there are more ...
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132 views

Why does the voltage goes away in my leyden jar?

This question is similar to this one in the sense that I have my amateurish Leyden jar and I'm supplying ~7.5v from 5 batteries (~1.5v each) in series. Some details and facts after experimenting: ...
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34 views

Query regarding a published description of a mechanical hydraulic system analogous to $V = IR$ in an electrical system

The screenshot is taken from the wikipedia article for a resistor - https://en.wikipedia.org/wiki/Resistor I understand that a larger head results in greater hydrostatic pressure, therefore a greater ...
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78 views

Current decay in RL circuit

I guess this has been asked before many a times. But I searched for it and couldn't find the question. Any kind of qualitative answer will be really helpful. When a magnetically charged inductor is ...
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2answers
62 views

Why exactly is the resistance of a conductor inversely proportional to the area of its cross-section? [duplicate]

Before I explain my query, I would like to clarify that I am a ninth-grader who got this question while studying the formula $R \propto \frac{1}{A}$ where $A$ is the area of cross-section. I have ...
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133 views

If Voltage = Joules/Coulombs than how can you have Voltage without Current?

Note: For the below question: I am ignoring exotic circumstances such as superconductors. My Problem: I came across this question regrading the ability to have a voltage without having current. ...
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57 views

Can an electron near thar the positive terminal of a battery make it all the way to the positive terminal? [closed]

Following Drude's model of conductivity, can an electron near thar the positive terminal of a battery make it all the way to the positive terminal? The electron is in the wire but near the positive ...
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73 views

Which of $I_s$ and $I_p$ will be greater? [closed]

I have two circuits: A circuit with two cells (emf=$12V$, internal resistance, $r'=0.5 \Omega$) and a bulb (resistance=$r$) connected in series:- A circuit with two cells (emf=$12V$, internal ...
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1answer
51 views

How AC circuit "Knows" how to divide the voltage?

Let's say we have an AC circuit with EMF source of $12V$ and a resistor of $3 \Omega$ . Then a voltage of $12V$ falls on the resistor. Now if we add another resistor of $3 \Omega$ , the circuit "...
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92 views

Current in each resistor

Switch $S$ is initially in the off or disconnected state. $E$ is the battery electromotive force with an internal resistance, $r$, of $10\, Ω$. The circuit given is:...
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68 views

Why will a circuit and resistors follow Ohms law when we connect different resistors together?

I assume in my question that all resistors follow Ohm's law. As I understand Ohm's law can be explained such that if we connect a resistor to a power source that is not time dependent then we have the ...
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41 views

Superinsulator infinite voltage

Everybody knows about superconductivity, at cryogenic temperatures conductor resistance drops to zero for direct current. There is lesser known related phenomena called superinsulator where material ...
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1answer
62 views

Is a simple circuit series or parallel?

Suppose we have a simple circuit in which a battery is connected to only one resistor. Is this considered as series or parallel?
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Failure of Drude like model and temperature dependence of ionic conductivity

Purcel models ionic conductivity[1] $\sigma$ in what seems to be a Drude like model, and gets for an electrolite like NaCl $$\sigma \approx Ne^2\left(\frac{N_+ \tau_+ }{M_+}+\frac{N_- \tau_- }{M_-}\...
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387 views

Is current (flow of charges) even possible in an ideal wire?

A typical electrical circuit with resistors only can be shown as in the fig. This is how every book and every website indicates the direction of current in the circuit diagrams. But I have a doubt ...
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20 views

Does the self-inductance and velocity factor of the elements of a dipole antenna change its resonant frequency?

Below are well known equations from Wikipedia for the resistance and reactance in the impedance of a dipole antenna. where a is the radius of the conductors, k is the wave number 2πf/c, η0 denotes ...
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123 views

The Concept of Parallel Resistors

If the equivalent resistance of resistors in parallel is lower than all resistors, does this mean each resistor is resisting less than its maximum (what is written on its label)? I am trying to ...
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35 views

What happens when an electromagnetic wave encounters a resistor?

So I know that the electromagnetic wave travels down the transmission line between the conductors and the fields are related by the characteristic impedance of the transmission line, and I know that ...
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62 views

Why does current become 0 in potentiometer?

The following image is from my textbook. I understand that using the formulae derived for $I_{2}$ if the emf of the battery is the same as the potential drop between points A and B we get $I_{2}=0$. ...
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1answer
24 views

Confusion over condition for zero current in potentiometer

Given the below circuit for calculating emf of a battery(sorry about bad drawing), I did some calculations using Kirchoff's 1st and 2nd laws. In loop 1 (cell E and ABC), we get $E-i_{1}R_{AB}-iR_{BC}=...
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2answers
40 views

Calculation of internal resistance of battery using potentiometer

In this circuit diagram current $i_{2}$ (passing through the lower circuit) is 0. Does this mean that the potential difference between c and b is zero? But then why is current flowing through the ...
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58 views

Is a Wheatstone bridge with 5 nodes possible?

The statement of the question is to find $R_x$ I think most Wheatstone bridges are of 4 nodes where if a detector is connected in between two nodes, then when the potential difference across the nodes ...
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29 views

Does effective internal resistance of batteries depend on their size? If so how?

It was asked to us by our professor- Consider the AA and AAA batteries, what do we think will happen to the internal resistance, will it increase or decrease or can we actually tell something about it?...
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46 views

Thevenin equivalent voltage

I am trying to find the Thevenin equivalent of the following circuit: In regards to the equivalent voltage, I know (I have the answers) that it should be V + IR, but I am not sure how to get there. ...
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3answers
94 views

Current flowing through it is?

Below is the question. I have seen many answers on it and some of them describes that the (3 ohm, 3 ohm) and (6 ohm,3 ohm) resistor are in parallel. So if they are in parallel it means that the point ...
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1answer
40 views

Voltage across battery which is being charged

When I connect my 7 V battery (having 7 V voltage ) to a 10 V power supply then across the battery it shows the voltage being the same as the instantaneous voltage of the battery. Now if I connect the ...
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44 views

Accumulation of charge and potential difference across a resistor

If there is no accumulation of charge across a resistor, how can a potential difference (that is, potential drop) be created across it?
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Is there a difference between zero resistance and dissipationless transport?

Zero resistance in superconductors is what I have learned in university and in textbooks. But in the field of topological insulators, I have seen the phrase "dissipationless transport" get ...
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93 views

Has a true Superconductor ever been produced?

Having a conversation with a friend, we where discussing about the conductivity and resistance changes of superconductors. He insisted that available superconductors produced by universities or ...
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1answer
53 views

Symmetry in electrical circuits [closed]

I was able to solve the above question by assuming potentials( Nodal Analysis), but the solution was very lengthy as i had three variables and had to solve three equations. Is it possible to solve ...
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2answers
68 views

Potential difference of a resistor

The resistor causes a potential difference across its end points but nowhere is written what is the direction of this difference. Is it from positive to negative or negative to positive. I will take a ...

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