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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0answers
23 views

Finding resistance tough problem can anyone solve it? [closed]

I have designed this problem by my own but not able to find solution can anyone help me?
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1answer
23 views

How does voltage behave in a parallel circuit?

I am studying the series and parallel combinations of capacitors and resistors. I do know that voltage is divided in series whereas it's the same for all circuit components in parallel combination and ...
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1answer
29 views

Grounding a simple circuit?

Suppose I have a simple DC circuit consisting of a battery of voltage $V$ (no internal resistance assumed), and a resistor (resistance $R$) connected in series by conducting wires. Because the wires ...
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3answers
919 views

Proof of internal resistance acting like it does

I believe Ohm's law via the drude model (about average collisions time). Right after, I read about internal resistance of a battery, and they used Ohm's law as a justification. That doesn't make sense ...
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29 views

What is the current flowing through the ammeter? [closed]

Could someone please tell me what I'm doing wrong? I'm getting decimal values, but the answers should be integers. I think I messed up in the equations. My equations using Kirchoff's loop rule are: $$...
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2answers
29 views

How can you expect a “fractional resistance change” with change in temperature?

I was learning about temperature dependence of resistance on a website that states as follows. An intuitive approach to temperature dependence leads one to expect a fractional change in resistance ...
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0answers
37 views

Incongruent expressions for $E$- and $B$-fields based on approach

I am having two issues with Maxwell's equations in the following problem: A thin conducting disc has radius a thickness b and electrical resistivity ρ. It is placed in a uniform time-dependent ...
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0answers
21 views

Potential difference between two cylindrical conductors [closed]

How to find potential difference between two cylindrical conductors given these? I have an idea how to solve this using $R = pL / A$ but I have no idea how to get the equivalent resistance using the ...
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2answers
39 views

Does electronic drag exist?

I have an aluminum desktop toy that is not magnetic but when I spin it and move some high strength neodymium magnets near it slows down a lot faster than normal. Is this forming some kind of eddy ...
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1answer
64 views

What is the bump in the resistivity vs temperature curve of the nichrome 80 wire?

I have measured the resistivity of a nichrome ($80$ Nickel $20$ Chrome) wire as a function of temperature. Because my setup is quite crude (just a power supply and a couple of multimeters to measure ...
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1answer
30 views

Finding resistance of infinite grid of resistors doubt in common method

While finding the resistance for an infinite square grid of resistors streching in all direction for two adjacent points. iT is assumed that the current coming out from the wire is same in all ...
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1answer
123 views

Longitudinal conductivity from density of states (DOS)

It is well-known that using the so-called Streda formula, the transversal conductivity $\sigma_{xy}$ and thus the Hall conductivity in a two-dimensional material is given as the derivative of the ...
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1answer
22 views

RL circuit with AC source transient

I have a simulation of RL circuit connected with an ac source. Any one can tell me please that why the peak of the current during the first positive half cycle is higher than the peak of current ...
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1answer
35 views

Transient in RL circuit

Why the transient current will die off in series RL circuit with AC source? Every time the ac voltage source reverses direction so does the current and the current has to pass through the same ...
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1answer
35 views

Is saying current as function of voltage same as current as function of $R$?

Is saying that current as a function of voltage same as saying current as voltage of Resistance? And can we say both: current as function of voltage and resistance.
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2answers
71 views

Electrical impedance [closed]

I really just wanted to confirm if my understanding about electrical impedance in an AC circuit is correct. So essentially the equation of impedance that $(\text{mod }Z)^2 = R^2 + (\omega L-\frac{1}{\...
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1answer
49 views

The Drude model appears to be inconsistent with itself?

According to the Drude Model, we have that $$\vec{J}=\frac{ne^2 \tau}{m_e}\vec{E}$$ where $\tau$ is the mean free time of each electron and $n$ is the free electron density. This is simply ohms law ...
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1answer
98 views

A contradiction between the Drude Model and Ohm's Law?

Using the Drude Model, we get that $$\vec{J}=\frac{ne^2 \tau}{m_e}\vec{E}$$ where $\tau$ is the mean free time of each electron and $n$ is the free electron density. This is simply ohms law and hence ...
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1answer
68 views

Voltage of capacitors after long time ($RC$ Circuit) [closed]

I'm currently taking a course in electromagnetism, and I got stuck with this problem: The Problem: All of the resistors and capacitors have the same values, $R$ and $C$ respectively. The circuit is ...
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3answers
54 views

Why doesn't Current through a resistor decrease with voltage drop?

I'm teaching DC Theory. I started the class with a simple circuit. A 24V voltage source and a 8000 ohm resistor. As I was previewing Kirchoff's Law for Voltage a student asked... "If the voltage ...
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1answer
37 views

What is the difference between the two formulas for each of resistance and capacitance?

Resistance and capacitance (of parallel plate capacitors) both have two formulas for them: $R=V/I$ and $R=ρL/A$ for resistance, and $C=Q/V$ and $C=ƐA/d$ for capacitance. For any given resistor and ...
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3answers
77 views

Why are these resistors not in series? [closed]

this is the circuit in question. I treated $R_1$ and $R_2$ as resistors in series, and $R_3$ and $R_4$ as resistors in series. Then the equivalent resistors were combined in parallel. However, this is ...
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1answer
27 views

Heat Energy $\propto 1/R$ or $\propto R$?

I know that heat energy can be calculated by $I^2 R t$. Therefore, it's directly proportional to resistance. However, $$I^2 R t = \frac{V^2}{R}t$$ In this case, won't the heat energy be inversely ...
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2answers
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Can deadly electrocutions be prevented by wearing a simple wire?

One way to die when working with electricity is for enough current to pass through your heart, not much is needed. Often you are protected by wearing shoes or by the current flowing through two parts ...
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0answers
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Is it possible to arbitrarly shorten the oscillation path of the electrons inside an inductor just by increasing the number of turns?

Is it possible to arbitrarly shorten the oscillation path of the electrons inside an inductor just by increasing the number of turns?Is it possible to force them to oscillate between neighboring atoms ...
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2answers
257 views

Can the current through this $6 \text{ }\Omega$ resistor be zero? [closed]

In other words, can the $6 \text{ }\Omega$ resistor below have $I = 0$? I think the answer is yes, depending on the direction of the current. Also, what do the negative $\epsilon$ values in the ...
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3answers
67 views

Doubt regarding concept of current electricity

Recently I started with concept of power provided by battery in moving charge from one point to other in a wire. NCERT says that "if charge were to move in conductor free of collisions then the ...
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2answers
23 views

Can we measure resistance of a diode using Ohm's law $V=IR$ for a specific value of voltage and current?

As a diode doesn't follow $V$ proportional to $I$, I was wondering if we can use Ohm's law to calculate its resistance for a specific set of voltage and current, as its resistance varies as per the ...
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3answers
61 views

Is the 'electrostatics' condition impossible for a point charge existing in space with conductivity?

It is a known equation that: $$ \vec{j} = \sigma \vec{E}$$ Where $\vec{j}$ is current per area density, $ \vec{E}$ is the electric field and $\sigma$ is the conductivity. Consider the set up of having ...
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2answers
72 views

If $I \propto V$, then why is $R = V/I$ and not $I/V$?

I know that the current flowing through a conductor is directly proportional to the potential difference across its ends (by Ohm's Law). Hence, I ∝ V V ∝ I R = V/I, where R is a constant (Resistance) ...
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1answer
36 views

What is impedance?

I'm looking at impedance in the regime of a waveguide. I have not been able to find much on what impedance actually is apart from (ratio of electric over magnetic field strength). But what really is ...
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Combination of resistors [duplicate]

The question is find the potential difference between points A and B i.e. (V(A)-V(B)) in the network given.
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4answers
462 views

How does Ohm's law work? Can a resistance change depending on the applied voltage?

I'm refreshing my memory on electromagnetism, and even though I thought I completely understood Ohm's law, today, while reading my textbook I came across the following. My question is, what does '...
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0answers
18 views

Rheostat at 0% interaction with Ohm's law

While working on an assignment, I recently came across something that I can't understand. I have a rheostat and an ammeter connected in line. When the rheostat gets the value $0$ I get a reading on ...
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2answers
35 views

Power of Bulbs Connected in Series and Parallel

Let's say that I have a circuit consisting of a power supply of $220V$ and $2$ bulbs of power-voltage rating $40W-220V$ and $60W-220V$ in series. How would I calculate the current flowing across the ...
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6answers
84 views

Current through a battery

Today was my first class in circuits.(I am moving to 11th grade). We were given the following circuit. After analyzing potential differences and finding current in the resistor , we found that ...
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1answer
33 views

Which statement is right for capacitor in steady state? [closed]

what should should I say for a capacitor in steady state is the potential drop in capacitor 0 due to no current the current in capacitor 0 due to no potential drop or? For the former statement I ...
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0answers
38 views

Wave impedance in a wave guide

I'm trying to get a better understanding of impedance for a wave guide. First of all, my current understanding of the topic is that its a ratio of the electric field amplitude over the magnetic field ...
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2answers
34 views

What happens when a bulb fuses in a parallel circuit? [closed]

Let's say there's a parallel circuit consisting of some bulbs (which are lit up). If one of them fuses, I know that the others would continue to glow. But because one of the bulbs has fused, would the ...
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0answers
42 views

How to find the canonical equations of the RLC circuit

First, I consider the LC circuit with an ion in the capacitor, which is like this: The current $I$ can be derived easily by using Shockly-Ramo theorem \begin{equation} I = -\frac{qp}{dM} + C\dot{U} \...
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0answers
23 views

Divergence of charge velocity

$$ \mathbf J=\sigma \mathbf E \\\rho \mathbf v=\sigma \mathbf E $$ Taking the divergence of both sides: $$ \rho\nabla\cdot\mathbf v=\sigma\nabla\cdot\mathbf E $$ Subsituting $\nabla\cdot\mathbf E = \...
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4answers
482 views

Do resistance have to heat?

Not a physicist. Is there a way to build resistances that do not heat when opposing current? More generally, is it necessary to waste energy to resistance? If I cut a wire, there will be an almost ...
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2answers
39 views

Can someone please explain the work of a resistor?

Well I want to know what does a resistor do let our electrical appliances from burning in a circuit I know it does not slow the current flow so what does it really do?
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28 views

Does a bulb offer still offer resistance even after it gets fused? [duplicate]

Sorry, for my naivety this is my first time posting here. But, my question is that will the bulb offer any resistance after it's fused? I know that no current can flow though the fused bulb i.e. $I=0$....
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2answers
48 views

What does a resistor do if not slow the current flow in a series circuit?

If the current is same in the series circuit then what does a resistor do to really if not less the flow of electrons?
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1answer
60 views

Why is the resistance proportional to the length squared in a wire?

I don't understand why the $R∝L^2$ (given that the volume doesn't change.) Eg: If the resistance of a wire is $3 \ \Omega$ and the length extends by $1.5$x the amount, then the new resistance will be $...
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0answers
48 views

Explaining Ohm’s Law using quantum mechanics

This is a follow up question to my earlier question here: Increasing the Voltage, Ohms law, what am I missing? A short summery of what was the problem in my original question is this: We have a ...
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1answer
42 views

Simple Circuit analysis [closed]

Someone could explain to me why $U_{in} = \varepsilon \frac{R_1}{(R_1+R_2)} $?
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1answer
27 views

What happens to the charges when a resistor is short-circuited?

let's consider a parallel between a short circuit and a resistor $R$, supplied by a voltage source $V_S$ with a series resistor $R_S$. Circuit Theory description: the resistor $R$ is completely ...

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