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

learn more… | top users | synonyms (1)

0
votes
0answers
10 views

What is the resistance of ionised Xenon gas?

I need to know the typical resistance of ionised xenon gas inside a xenon flash tube, so I can use circuit analysis to calculate the flash duration. I know that a 180uF capacitor is charged to ...
0
votes
0answers
15 views

Exact expression for the coefficient in Bloch-Grüneisen (BG) formula?

In most representations of the BG formula, there is a coefficient (usually left vague as an experimental parameter, but sometimes written out "analytically") in front of the integral: $$\rho=\rho_0 +A ...
0
votes
0answers
13 views

Current pass through different branch of network [duplicate]

How current knows that resistance in any branch of network is law show that more proportion of it pass through that branch?
-1
votes
2answers
96 views

Electrical resistivity: the effect of adding electrons

Consider a copper wire of fixed length and cross-sectional area, and apply an electric field to the wire induced by a fixed potential difference $V$ across the two endpoints of the wire. By Ohm's law, ...
-2
votes
0answers
26 views

Question about Sharvin resistance

I am studying the ballistic regime. In ballistic regime, there is Sharvin resistance between 2 contacts. it depends only on the Fermi surface and the area of contacts. In this paper enter link ...
0
votes
2answers
64 views

Why is this circuit component on without a potential difference?

From the following graph, determine whether (h) will be on or off: I think (h) should be off because there is no potential difference across it. Is this correct? Edit: Using the method provided ...
1
vote
1answer
42 views

Transfer function of an RC circuit

I'm trying to reach the transfer function of an RC circuit which I am told is $$\frac {V_R} {V_\text{in}} = \frac{R}{\sqrt{(R^2 + \frac {1}{\omega^2 C^2})}} \cos(\omega t - \theta) \, .$$ Is this ...
1
vote
2answers
48 views

Proof for Resistance is directly proportional to length and inversely proportional to the area of cross-section?

I have heard that Resistance is directly proportional to length and inversely proportional to area of cross-section. Can someone give me a practical explanation for this?
-1
votes
2answers
41 views

How long does it take for a capacitor to be fully charged if voltage is decreased? [closed]

Above is the picture of the circuit pertaining to this question. The question asked for the time it will take for the capacitor to get fully charged when the switch is in position B? So i guess the ...
8
votes
5answers
3k views

How can one derive the Ohm's Law?

I am looking for the derivation of the Ohm's Law i.e., V is directly proportional to I. Can someone help me with it?
0
votes
2answers
55 views

Resistance of hollow metal sphere

A hollow metallic sphere has inner and outer radii $a$ and $b$ respectively. How to calculate its resistance between two a points $A$ (on the inner surface) and a point $B$ (on the outer surface)? ...
1
vote
2answers
30 views

How do you model the resistance across a symmetric sheet of plastic, streched (think ceran wrap) between a circular anode and cathode?

Here is the problem. You need to model the resistance across a circular sheet of polypropylene (plastic). The resistivity of polypropylene is 1E15 Ohms per meter. The expression for resistance on a ...
1
vote
0answers
26 views

Negative resistance temperature coefficient of metals

How is it explainable that some metals have their electrical resistance increased while other metals act the other way? When the temperature of a metal rises the molecules move faster and from my ...
4
votes
1answer
60 views

Graph of Electrical Resistivity of Air vs Air Pressure

I've search many place ( Google, forums etc ) but can't seem to find anything that explains the Relationship between: Electrical Resistivity of Air vs Air Pressure Constant Variable: ...
2
votes
3answers
49 views

Why is resistance across a load the V per I rather than the V per Q?

There is a load that resists the flow of electrons. This causes a voltage drop, meaning it creates a potential difference between the 2 sides of itself. This property, a load creating a voltage drop, ...
-3
votes
2answers
37 views

Resistors and dependent voltage sources

why not $i(2\;kΩ)=15\;mA$ and $i(5\;kΩ)=4\;mA$?
-3
votes
2answers
44 views

Doubt on resistor circuit [closed]

How are we able to flip the triangular resistor to the opposite breaking its connection with the lower 2r resistor?
0
votes
0answers
51 views

Resistance of a metal sphere

How would you go about calculating the electrical resistance of a sphere when you only know it's radius and conductivity? I know with cables you can use $$ R = L/(g \cdot S),$$ but I don't know how ...
0
votes
1answer
27 views

Does the power of the resistor change when the battery is changed?

Wanted to know whether the changing of a battery (potential difference)affects the change of power consumption of a resistor of a bulb. please tell me how the change will occur?
1
vote
1answer
35 views

Why, microscopically, is the voltage drop across a resistor affected by the current through it?

If voltage is a potential difference, describing how much energy will be lost per unit charge as charge carriers pass through the resistor, why would the rate at which charge flows (i.e. current, ...
0
votes
1answer
27 views

Calculating resistance [duplicate]

I am really confused please help me! I want to find the resistance between a and b! But i am not able to understand which resistances are in series or which are in parallel! What i think- e and a ...
0
votes
0answers
18 views

Total current - differential equation [duplicate]

Consider the circuit below consisting out of a capacitor C and two identical resistors R. For $t<0$ the switch is open and the capacitor is uncharged. At $t=0$ switch is shut and the circuit is ...
0
votes
1answer
55 views

Circuit with capacitor and two resistors - total current - charge - differential equation [closed]

Consider the circuit below consisting out of a capacitor C and two identical resistors R. For $t<0$ the switch is open and the capacitor is uncharged. At $t=0$ switch is shut and the circuit is ...
7
votes
5answers
804 views

What causes contact resistance?

When two components are combined in an electric circuit, there is apart from their own resistances a contact resistance at their junction. This causes a sudden voltage drop of ...
1
vote
1answer
33 views

Loss in energy while charging a capacitor

Suppose a capacitor having capacitance $C$ is being charged using a cell of emf $E$. By the time the capacitor is fully charged, the cell has supplied $QV$ energy while the potential energy of the ...
2
votes
2answers
76 views

Calculating the resistance of a 3D shape between two points

If I have an arbitrarily shaped object made of a uniform material of some specified resistivity, how would I go about calculating the resistance between two measurement points with known contact ...
2
votes
2answers
70 views

Why does voltage change in series circuit but not in parallel circuit?

Voltage divides after every resistor in series but not when placed in parallel. Please explain this with using very less or no mathematical equations. I have tried searching for an answer online but ...
5
votes
1answer
68 views

How uniquely determined is the impedance of an infinite-chain circuit?

A recent question asked how to find the impedance of an infinite chain of series-plus-parallel circuits. The standard trick is to split the chain after the first link, and treat the tail of the ...
0
votes
1answer
54 views

Impedance of the infinitely long circuit

Is there a way to find impedance of the infinite circuit like this? It will be much simpler if one has either parallel or series combination but here is both.
0
votes
1answer
26 views

Electricity parallel combination

Why is resistance lower in a parallel configuration and therefore current is more? Shouldn't resistance be addition of all resistor's resistance?
-1
votes
3answers
54 views

Electricity series connection of resistor

In simple circuit is current in wire different from current in resistor as wire also opposes the flow of electrons so wire should also be added in series connection of resistor
-1
votes
2answers
163 views

Resistor cube problem solving method

I was solving problems from Irodov when I came across the method called point of symmetry method. I cant find this method anywhere. So what is this method? Here is the link to the problem solution ...
1
vote
0answers
15 views

Is their a visual difference between air-gap sparks of the same voltage but different current?

For example, if this spark gap has a kilovolt of power behind it @ 1A and the other is also at a kilovolt but is @2A will there be a visual difference (i.e. will the one with higher current be ...
0
votes
2answers
51 views

What happens to half of the energy in a circuit with a capacitor?

For a simple circuit with a battery supplying a voltage V to a capacitor, let us assume that the charge on the capacitor is Q. Now, the work done by the battery or the energy supplied is given by the ...
1
vote
2answers
51 views

Why does electrical impedance have as many parameters as it has?

The impedance of a circuit is written: $$ Z(R,L,C,f) = R + j ( 2 \pi f L - \frac{1}{2 \pi f C} ). $$ What is the line of thinking that frequency, resistance, capacitance, and inductance are the only ...
0
votes
3answers
43 views

Where to start from and how to proceed for finding the resistance here? [closed]

Can anyone kindly help me in finding the effective resistance between A and B in the below goven case ? Each resistor is of 16 ohm .. Thank you .
0
votes
2answers
38 views

Is the Hall coefficient a resistance?

The Hall coefficient is defined as this: $$R_H=\frac{E_y}{j_xB_z}.$$ Always as $R_H$. I am currious as to how to use this coefficient? Is it the y-direction resistance/resistivity (it is very close ...
0
votes
1answer
66 views

Ohmic Heating in Wires

please could someone tell me why Ohmic losses are always referred to as $I^2 R$ losses? Here is my problem. If the power coming from a power station is fixed then you can either deliver this power as ...
0
votes
1answer
21 views

Derivation of impedance matching formula

When matching impedances with a quarter wavelength coupler, how do I derive that its impedance has to be $$ Z_2=\sqrt{Z_1 Z_3} $$ where $Z_1,Z_3$ are the impedances of the adjacent materials?
1
vote
3answers
66 views

What does it mean when we say that power of a bulb is 10 W? Since $V/I=$ resistance is a constant, how can power $=VI$ be a constant?

My question is simple. In Ideal situation, at constant temperature, we know that normal appliances like a filament bulb has straight Voltage vs Current graph, meaning its resistance is constant or ...
0
votes
0answers
26 views

Initial current, RC Circuit

The task goes like this: The voltage between the points A and B, in the circuit diagram below, is 100 V. What's the initial current through the resistor when we close the switch S? (Other components - ...
0
votes
1answer
103 views

Resistance & temperature of semiconductor

From what I have read about semiconductors, the reason their IV characteristic shows a decrease in resistance is because as voltage is increased, current is increased. However, the reason for the ...
-1
votes
3answers
98 views

Why does the resistance halve when two resistors of equal resistance are in parallel? [closed]

This is the question and answer to a homework question and I do not understand why this is the case. What is the logic behind it?
0
votes
1answer
53 views

Equivalent Resistance [duplicate]

I've never had problems in finding the $R_{eq}$ of a circuit, but in this case I don't really know how to do it:
0
votes
2answers
133 views

Ohm's law holds at constant temperature - what about Joule heating?

Ohm's law states that the resistance of a conductor is constant provided its physical conditions, such as temperature, remain constant. But what I'm thinking is that as you increase the voltage across ...
0
votes
1answer
67 views

Confusion with potential difference [closed]

I was trying to solve a hard problem involving a circuit like this: Find the reading on the voltmeter (red ones are resistors) I don't know how to think about potential difference across branches ...
0
votes
2answers
70 views

Calculating the energy supplied by a battery

If you wanted to calculate the energy supplied by a battery in time $t$ you would use $E=VIt$ where $I$ is the current through the battery. If the internal resistance is $r$ we could also use ...
1
vote
1answer
48 views

Calculating resistances in parallel

I was playing around with a question involving resistances in parallel. I realized that $n$ equal resistors (resistance $R$) in parallel have combined resistance $R/n$. I proved this using ...
1
vote
1answer
114 views

Question about ohmic conductors

I'm having some trouble understanding Ohm's law. My trouble is with the different ways it is described when referring to ohmic and non-ohmic conductors. If someone can answer this question I think it ...
1
vote
2answers
52 views

Resistors in parallel: How do I make this rigorous? [closed]

In my revision guide it says "when two resistors are in parallel, the current has two paths it can flow through so there is less opposition to the current. This is why the combined resistance is less ...