# 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
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)
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-...
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 ...
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 ...
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 ...
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 ...
1answer
34 views

0answers
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### 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 ...
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 $R$ ...
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 ...
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 ...
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 ...
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: ...
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 ...
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 ...
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) ...
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 ...
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 ...
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 ...
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 ...
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, ...
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 ...
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?
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?...
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 ...
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 ...
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 ...
1answer
75 views

### Is resistance determined by electron mobility?

How Is resistance determined by electron mobility for a given resistor or wire.
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 ...
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 ...
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? ...
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 ...
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) ...
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 ...
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 ...
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.
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 $J$?
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 ...
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 ...
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 \$...