Questions tagged [electrical-resistance]
The tag applies to electrical resistance and resistors. DO NOT USE THIS TAG for non-electrical resistance.
1,536
questions
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0answers
24 views
It is possible that without resistance current flow a conductor [on hold]
It is possible that without resistance current flow a conductor (answer with proof by)
0
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0answers
6 views
“Directional” conductivity in linear flux-potential laws?
Question: Has the notion of "directional conductivity" been defined and used in the study of heat flow and electric current flow?
Context: The table below gives three laws that describe linear flux-...
0
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1answer
38 views
Maximum metallic resistivity: dependence of resistivity on temperature
The electrical resistivity of metals usually increases with temperature. For a metal like copper at room temperature it increases almost linearly with temperature. At melting point we see a jump in ...
3
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1answer
39 views
Current in RC circuit
Why is current drawn in an RC circuit (in a circuit powered by DC voltage supply) independent of the capacitor used?
While the capacitor is charging current drawn from the battery only depends on ...
6
votes
2answers
477 views
From where do electrons gain kinetic energy through a circuit?
Supposing an ideal wire, How do electrons accelerate and gain kinetic energy?
What I understand:
When a circuit is opened ,electrons are crowded at the negative term of the battery and have high ...
0
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0answers
45 views
A Simple RC Circuit [closed]
This is the most simple Rc circuit (i have just started learning) .My questions regarding this is-
(This is a dc voltage supply)
Will capacitor get charged by the potential drop of resistor or ...
0
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1answer
34 views
LCR circuit (AC source) potential difference across capacitor
For a LCR circuit connected to AC source of emf$$E= e\sin(ωt)$$ and let the current in LCR circuit be I then $$I=i*\sin(ωt+Φ)$$ then it is given that potential drop across the capacitor is V.ie$$V=-...
1
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1answer
73 views
How can I calculate the equivalent resistance of this circuit with resistors in parallel with wires? [closed]
Problem:
Calculate the equivalent resistance, $R_\text{eq} ,$ of this circuit:
$\hspace{50px}$.
My solution attempt
Тhe $12 \, \Omega$ resistor and the $6\, \Omega$ resistor are in parallel, ...
0
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1answer
34 views
What is causing the current sinusoidal delay regarding voltage in inductive circuits? [duplicate]
Do electrons acquire some electromagnetic 'mass'as they have so much slow acceleration in the coil due to obviousely electromagnetic field acting on them or it is just the net voltage that drops down ...
0
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3answers
96 views
Basic question on Ohm's law
I have what I assume is a very basic question on Ohm's law. Let's say that we have $n$ equal light bulbs in a series with a battery. We know that $$ U - IR - IR - \cdots -IR= U - nIR = 0.$$ Solving ...
0
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1answer
23 views
Why are the times at which max rate occurs different for the energy of a capacitor and the battery
When charging a capacitor the rate at which the battery provides energy is maximum at $t=0$ but the time at which the rate of increase in the energy of a capacitor is maximum is $t=CR\ln(2)$ (where $C$...
6
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1answer
950 views
What is the resistivity of copper at 3 kelvin? [on hold]
I couldn't find the value of resistivity of copper at 2.73K on google
0
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1answer
34 views
Mutual inductance circuit analysis
given the following circuit, I need to find $ I_1(t) $ and $ I_2(t) $
(forgive my microsoft paint skills ;) )
I've come up with a solution, and I wish to check with you if it is current or, ...
1
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4answers
71 views
What is the intuitive explanation for high voltage and low current?
By the formula $$P=VI$$ we can say that the voltage can be increased and the current decreased by keeping the power constant. It is mathematically and experimentally right. But is there a way to ...
0
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4answers
94 views
Resistors are used to reduce current to prevent light bulbs from “exploding” but it's also said that “current remains same at all points in a circuit”
Resistors are used to reduce current in order to prevent light bulbs and other electrical components from “exploding”, but it is also said that “current remains the same at all points in a series ...
0
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1answer
47 views
What does Ohm's law mean in this context?
In this problem Griffiths states that the potential at radius $a$ and angle $\phi$ is $V(a,\phi) = \frac {V_0 \phi}{2 \pi}$
And yes that satisfies the boundary conditions, that at $ \phi = \pi$ , $ V=...
3
votes
2answers
131 views
Circuit - solve Kirchhoff's laws with determinant?
Here is an exercise from my textbook.
]1
At first I solve it by using Kirchhoff's laws directly and using complex impendance:
$$U_{in}=\frac{1}{Cs}(i_1-i_2)+i_1R_1$$
$$0=R_2i_2+\frac{1}{Cs}i_2+\frac{...
0
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0answers
17 views
Why to use non-inductive resistances in Callendar-Griffiths bridge?
Worsnop in his Advanced Practical Physics for Students states that
All the resistances should be 'non-inductive', for in this method it will be seen that the galvanometer is permanently connected ...
1
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1answer
31 views
What is $v(t)$ in a sliding conducting rail in a magnetic field?
This is problem 7.7c from David J. Griffiths - Introduction to Electrodynamics.
A metal bar of mass $m$ slides frictionlessly on two parallel conducting
rails a distance $l$ apart. A resistor $R$ ...
1
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3answers
59 views
Would we need a battery if there was no resistance?
I'm struggling to wrap my head around this idea.
Imagine that we have a wire with no resistance ($R=0$). According to Ohm's law $V=IR$, the voltage drop ($V$) between any two points would be 0, and ...
1
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0answers
38 views
Potentiometer's working
I know that in a closed circuit with multiple batteries, current is provided by the battery which has the maximum voltage.
Let's suppose that $E \gt V$. Now, the voltage $V_b$ at point $b$ will ...
1
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2answers
47 views
Minimum and Maximum values of Effective Resistance [closed]
Assume we have resistors of resistances $R_1$, $R_2$, $\ldots$ , $R_n$. Let these resistances be connected in a network. Are the following statements true?
$(i)$ Effective Resistance is maximum when ...
4
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2answers
101 views
How do electrons lose their kinetic energy in ideal wire?
Electrons keep accelerating due to the electric field (produced by the battery) along the circuit. So electrons gain kinetic energy, hence their drift velocity changes. But this is not the case: ...
1
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3answers
75 views
Why voltage is same across parallel resistance?
Since voltage stands for energy per unit charge to be used to carry it from one point to another,why should energy per unit charge be same for two resistors of different resistances,?the energy ...
0
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0answers
35 views
In the equation $R = R_0 [1+αt(∆T)]$ is $R_0$ the resistance only at 0K/0°C?
For example, we're asked to find the resistance at a temperature 20°C, we know that the resistance at 10°C is 5 ohm, and we know the value of the temperature coefficient of resistance. Can we put Ro ...
2
votes
3answers
61 views
Electric potential and drift speed of electrons through circuit
What I have since learned: (Tell me If I am wrong)
In circuits ,Batteries provide electric potential difference (voltage) ,This difference creates electric field (Over the conductor or the wire) ...
0
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0answers
36 views
Is this explanation of Voltage Drop correct?
As a general outline of what happens when the battery is turned on, here is what happens:
When the battery is turned on, a wave propagates within the circuit to determine the current of the sytem.At ...
0
votes
1answer
41 views
Why should the relation (current density)= (resistivity)×(velocity of charge) [$j = ρ v$] be applied to each type of charge carriers separately?
This is from the class 12 physics NCERT Part I.
The relation $\mathbf{j} = \rho\mathbf{v}$ should be
applied to each type of charge carriers eeparately.
In a conducting wire, the total current ...
0
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1answer
62 views
Why does have a shunt resistance in parallel to a galavanometer decrease the amount of current passing through the galvanometer?
The way I understand it is that when you put shunt the current starts flowing more into the shunt resistance than the galvanometer, Then how can galvanometer give a correct value for actual current of ...
2
votes
2answers
46 views
Electric current and drift velocity
I have seen in several textbooks that say that when we connect a conductor with a battery then electrons start moving (drifting) in the battery in random up and down motion in the opposite direction ...
0
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1answer
41 views
Forces inside battery
The title itself seems silly to me but here is this question,
A constant electric force of $8\ \text{N}$ acts in the direction shown and constant non electric force of $10\ \text{N}$ acts rightward, ...
1
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2answers
39 views
Resistance between steel wires in water delayed response
I am trying to make a wire wave gauge by measuring the resistance between two stainless steel wires. Theoretically, the output voltage reading should change the deeper the wires are in the water. If ...
1
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3answers
48 views
RC Circuits- Charge and Energy
It takes longer for the charge in an RC circuit to fall down to half its initial value than for the stored energy. Why?
3
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4answers
114 views
In a circuit having one resistor why do the electrons lose all their potential energy across that resistor and not do so if there are many resistors
In a simple circuit which consists of a battery and one resistor, why do electrons lose all their potential energy across this one resistor regardless of the magnitude of the voltage or the resistance?...
1
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1answer
61 views
What makes the internal resistance of a battery at microscopic level?
What makes the internal resistance of a battery at the microscopic level?
And why does voltage drop when in a circuit compared to the open circuit voltage?
I think that the field between the ...
1
vote
1answer
44 views
Why is neper frequency called a frequency?
In the context of complex frequency of RLC circuits, the real part is called neper frequency, according to units it's understandable that it has 1/s as the unit which is same as frequency but what is ...
9
votes
4answers
2k views
How do resistors generate different heat if we make the current fixed and changed the voltage and resistance? Notice the flow of charge is constant
Consider having a circuit which consists of a battery and one resistor.
$V = 10$ volts, $R = 5$ ohms, so $I = 2$ Amperes, and
$P = 20$ watts.
If we double the voltage and resistance, the current ...
2
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1answer
75 views
Is resistance determined by electron mobility?
How Is resistance determined by electron mobility for a given resistor or wire.
0
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2answers
46 views
Heat developed in a circuit
Suppose I have a simple circuit with capacitors, a battery and a key. There Is a change in energy stored in capacitors when the key is closed. How will I find the heat developed in the system?
Is the ...
0
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1answer
18 views
Rates of charging in an RC circuit when components are partly charged initially
Just to be sure of my reasoning I am describing a simplified version of my problem
Two capacitors of capacitance $C_1$ and $C_2$ are connected in series to a battery of emf $V$ volts having some ...
1
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5answers
129 views
Which type of conductors don't follow Ohm's law? [closed]
Which type of conductors don't follow Ohm's law?
I know that semiconductors and superconductors don't follow them, but why?
And what about ideal conductors. What are they? Do they follow ohm's law? ...
3
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1answer
60 views
Why does current arrange itself in such a way as to minimize power loss in resistors connected in parallel?
In problem 2 in Problem Set 6, it is said:
"Electricity prefers to flow in the way that minimizes energy loss to resistance."
Using Lagrange multipliers I was able to show that assuming the above ...
0
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2answers
114 views
What is the change of entropy for a resistor at constant temperature?
A 10 Ω resistor is held at a temperature of 300 K. A current of 5 A is passed through the resistor for 2 minutes. Ignoring changes in the source of the current, what is the change of entropy in (a) ...
-2
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2answers
48 views
Why inductor voltage at $t=0$ is equal to source voltage? [closed]
I am sorry to ask this elementary, fundamental and most repeatedly asked but i have some doubts that were not cleared during my undergrad days. I will try to present my doubts in following points.
1 ...
0
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1answer
42 views
Is Ohm's Law Valid for AC Circuits?
Specifically, let us talk about a circuit containing only an AC source and a capacitor. In this case, the current is 0 at the instant the source voltage is maximum. Same is the case when the circuit ...
0
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1answer
50 views
How to derive the $\Delta$-$Y$ formula for capacitors? [closed]
So, I've found a youtube video that first derives the formula for the resistors and then says the capacitance is the resistance^(-1). I was wondering if that would be the right approach.
3
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1answer
66 views
Is Ohm's law valid for water?
I have $E$ (electric field intensity) in water.
I want to find $J$ (current density).
I don’t know if Ohm's law ($J=\sigma E$) is valid for water.
If it is not valid, how do I may find out $J$?
0
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2answers
49 views
Will high voltage but low current glow a bulb?
Suppose I increase the voltage supplied to a building from a constant power source substantially by putting a transformer. Doing this would reduce the current substantially as well. So will the ...
0
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0answers
33 views
Does the potential difference between two points remain the same if there spatial location is changed?
I was working through this particular homework problem. Where I am required to find out the current flowing through the resistor A (4 ohms).
First of all I saw that the 2 resistors were in parallel ...
1
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0answers
31 views
Temperature Dependence of the Kubo Formula
I'm trying to calculate the DC conductivity of a Renormalized Fermi Liquid with Green's function
\begin{equation}
G(i\omega,k)=\frac{Z}{i\omega-Z\tilde{\epsilon}_k-ig\omega^2}
\end{equation}
where $...
