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

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1answer
27 views

How does the equation $1/I = r/E +R/E$ relate to $ y=mx+c$? [duplicate]

I have a graph of $1/$current against resistance, which is a straight line of positive gradient. I know that the gradient represents $1/V$ but I can't work out how the equation $1/I= r/E + R/E$ ...
0
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2answers
27 views

Calculating the time constant for charging a capacitor in a circuit [on hold]

Problem: Calculate the time constant for charging the capacitor in the shown circuit. What is the maximal charge on the capacitor? Attempt at a solution: Let current $I_1$ flow from the emf ...
0
votes
2answers
49 views

What does the gradient of a graph of 1/current against resistance graph represent?

I did an experiment to investigate how current varied with changing resistance and plotted my results on a graph of 1/current against resistance.The graph is a straight line showing $1/I$ to be ...
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1answer
27 views

Variation of infinite grid of ideal one-ohm resistors: what would be the equivalent resistance between 2 points in a 3D lattice?

I'm sure that many here are familiar with this famous problem that popped up on xkcd one day: On this infinite grid of ideal one-ohm resistors, what's the equivalent resistance between the two ...
0
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1answer
42 views

Difference of potential between points [on hold]

I have the following question: What is the potential difference between point A - B? Could somebody please explain me how should I count it? The voltage U=18V. I found out that V1=8V, V2=10V, ...
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0answers
18 views

Resistance in Potentiometer [on hold]

A potentiometer is shown in the figure. a) How will the balancing length be affected if resistance (R) is increased or decreased ? b) Will the balancing length be affected if resistance (S) is ...
-4
votes
1answer
26 views

How I can solve this ? (kirchhoff's law) Plz discuss it to me [on hold]

the remaining of question is ( careful choice of suitable loop can make it easier ? i choose outer loop and answer it like that: 10 Volt = ( I X 10 ohm ) + ( I X 10 ohm) but it give wrong answer ...
0
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0answers
29 views

Finding the component values of a series RLC circuit using an oscilliscope and signal generator [closed]

What methods could I use to find the individual values of the components - resistor, inductor and capacitor - of a series RLC circuit using an oscilloscope, signal generator and 10 ohm resistor. Where ...
0
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1answer
26 views

why activation energy of semiconductor changes as temperature changes

why activation energy of semiconductor thin films changes as temperature changes. I know that this is due to different conduction mechanisms. Intrinsic conduction mechanism which occurs at high ...
0
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3answers
72 views

Which of the following has higher resistance - milliammeter or ammeter?

The question is the same as the heading - Which of the following has higher resistance - milliammeter or ammeter ? Now my teacher's and my answers don't match. It is assumed that the spring constant ...
1
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2answers
48 views

Does the speed of electrons depend on energy?

I would like to know whether the speed of an electron depends on energy. If yes then in a circuit when electrons flow out of a resistor the energy decreases by a considerable amount, leading to the ...
0
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1answer
23 views

In a circuit, if voltage is established at both terminals, then how can components use up this voltage? [duplicate]

Suppose we use a 9V battery. Then the voltage between these two terminals is 9V. In other words, it would take 9 J of energy to move +1C of charge from the (+) to the (-) terminal by the electric ...
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0answers
16 views

Resistance of depletion region

The ideal diode equation is : I=Io[exp(qv/kT)-1]. My question is when we want to represent this ideal diode, it will be represented by a resistance of depletion region right? but is this resistance ...
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3answers
22 views

Resistance of capacitors

Please I would like to know how the resistance of the plates of a capacitors work? Is it the same as a resistor? If yes, is there electric field inside the plates like inside a resistor?
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0answers
15 views

Problem with the sign of the Thevenin resistance in a circuit

I have the following issue: when I want to find $R_{Th}$ for a circuit with dependent sources, I excite the circuit with a voltage Vo, and then proceed to find the resulting current $I_0$. Finally, ...
0
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1answer
30 views

Internal Resistor in a Diode

When we talk about the resistance of a diode (of the P and N region), is this resistance like the one inside an Electro-Motive Force or it acts like a normal resistor (external electric field exist)? ...
1
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1answer
35 views

Diffusion current and resistance of a diode

In a diode, there is a resistance in the p and n region, and electric field is required to move the charges in forward bias conditions. My question is: when there is diffusion current is the electric ...
0
votes
1answer
42 views

Calculate the resistance in serial and parallel circuits

I have a serial and a parallel circuit. In both of the circuits I am using two resistors.These two resistors have the same resistance $a$. In both the circuits I have tried reading the amount of ...
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0answers
9 views

Given temp and conductivity can I back-calculate to resistance, in order to plug in a new temp value and calculate a more accurate conductivity?

Background: I used a small CTD (conductivity, temperature, depth) recorder to log a series of dive profiles in a mixed coastal estuary. The recorder logged observed temperature and conductivity every ...
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1answer
50 views

Resistivity dependance on temperature

I'm just starting to study electricity and magnetism. The resistivity $\rho$ of a conductor is defined as $$\rho = \frac {\mathbf E}{\mathbf j},$$ where $\mathbf E$ is the electric field and ...
0
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0answers
90 views

Difference between rheostat and potentiometer & How connections are made to a simple rheostat?

I am confused about connecting wires to a rheostat. Can you please name and explain the parts of rheostat? Also how do we know which end of rheostat is to be used in circuits? In the last picture ...
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1answer
35 views

How to Determine and Verify Series and Parallel

I am having a lot of trouble visually identifying which elements in a circuit are in series and parallel is there a formal mathematical way I do this with Kirchoff's Law?
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2answers
53 views

Optimal method for solving circuit

This problem seems quite simple, and I can easily find a way to solve it but the possibility of error in my method is extremely high. This is just a sub-task of a bigger task but this is the only part ...
0
votes
2answers
312 views

Olympiad physics 1996 problem [closed]

I don't understand the official solution of the first problem of the 1996 International Physics Olympiad. They give this circuit: Each black box is a resistor of resistance $1\Omega$. They then ...
0
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1answer
34 views

Resistor color code extrapolation [closed]

I can't help wondering: what should the color stripes be on these?
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6answers
3k views

Could someone intuitively explain to me Ohm's law?

Could someone intuitively explain to me Ohm's law? I understand what voltage is and how it is the electric potential energy and that it is the integral of the electric field strength etc. I also ...
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2answers
69 views

Capacitance and voltage drops

Let's say that Switch $S$ is closed. I have a conceptual question: If a stream of particles acquire a potential difference upon exiting the battery, why will they lose some of that potential ...
0
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1answer
55 views

Load resistance adding with minimized power and voltage constraint [closed]

Consider the simple circuit below: Suppose $V$ and $R$ have set voltage and resistance values respectively, and you are to choose the resistance values for $R_1$ and $R_2$. However, you must choose ...
0
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1answer
29 views

Showing $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} \frac{R_1}{R_1+R_2}$ [closed]

Consider a voltage divider with $V_{out}=V_{in} \frac{R_2}{R_1+R_2}$. Show that for a small change in $R_2$, the voltage divider equation is: $\frac{\delta V_{out}}{V_{out}}=\frac{\delta R_2}{R_2} ...
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2answers
69 views

What is the real derivation of Ohm's law? [closed]

$I$ is proportional to $V$. But then how it is that I directly got $V=IR$? It looks impossible to handle this thing! If $I$ is proportional to $V$, then it must be $I=RV$. Why it is $V=IR$? The ...
0
votes
1answer
65 views

Relationship between electrical resistivity and density

I just read this answer on EE.SE and that triggered a doubt in me. If I were asked whether there is any relationship between the electrical resistivity and the density of a substance I'd answer ...
0
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1answer
68 views

What does a negative Thevenin-equivalent resistance mean?

What is the physical meaning of negative value of "Thevenin" resistance? Sometimes in the calculations, a negative value of Thevenin resistance appears.
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3answers
38 views

Current in an RC Circuit

If an $emf$ leaves from point A, the concepts at play in the following diagram are straightforward: at any time, the $I_{R}$ = $I_{c}$ as time increases, $\Delta V$ across $R$ decreases and it ...
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1answer
48 views

Direction of Current Flow in Complex Circuit

Physics Hypertextbook writes that "The current through the 1 Ω resistor most certainly runs from right to left." Why is that true? My approach: I arbitrarily assigned a counterclockwise ...
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1answer
36 views

Where are the negligible and infinite resistances, respectively, of the ideal am- and voltmeter?

Consider the picture below. An ammeter is shown to the left, a voltmeter to the right. They consist of a d'Arsonval galvanometer, which is a coil (with a pointer attached) that can rotate in a ...
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3answers
74 views

Why Voltage Drop is not Influenced by Resistor Value?

To my understanding, if a resistor reduces the potential energy of the current across it, then the current that leaves the resistor will have less potential energy and thus, less pressure or voltage. ...
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1answer
45 views

Why is there current in LC Circuits?

When we connect two electric sources (positive to positive and negative to negative) then the current that runs the circuit is calculated as follows: $ I = (E1-E2)/(2r + R) $ In case of an LC ...
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7answers
159 views

Why Two Equal Resistors Cut Voltage in Half?

I've been reading several books on electronics, one of them called "Electronics All-In-One For Dummies - D. Lowe (Wiley, 2012) BBS". It states that if two resistors of the same value, no matter the ...
0
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1answer
42 views

Variable Resistance

We know that the resistance increase with temperature or for exemple in an AC circuit, the resistance is superior to the same resistor for DC current due to skin effect. But my question is for a same ...
0
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1answer
31 views

How to locate the Oil-Water-Contact (OWC) from resisitivity log? What is enough abrupt change in resistivity from resistive gas to conductive water?

This is a real petrophysical log analysis chart with resistivity logs (laterolog log on the last row with rainbow plots and induction log on the second row with red, orange, purple lines) and little ...
1
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0answers
48 views

Solve symmetric circuits by a glance [closed]

How to know with just a cursory glance that the Voltage needed is zero ? i think there must be a way to know it , by symmetry or something
0
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0answers
107 views

How are band gap energy, dielectric constant (permittivity) and resistance related to each other?

The following three properties are related to current flow: Band gap energy Dielectric constant Resistance I would expect them all to have the same trend (i.e. higher band gap energy would cause ...
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0answers
13 views

Is there any equivalent to using a Laplacian matrix to find the “resistance distance”, but for impedance?

If you want to find the effective resistance between two vertices of a random network of resistors, you can calculate the "resistance distance" as shown in the link, which I'm pretty sure ends up just ...
0
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1answer
38 views

When do I use the various power-related equations? [closed]

Can someone please tell me when it is appropriate to use the equations $P=IV$, $P=I^2R$ and $P=V^2/R$?
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2answers
35 views

Physical Explanation of the steady state in RC circuits

Given a simple RC circuit with a resistance $R$ connected to a capacitor $C$, the differential equation that describes the voltage is $$C \dot V + V/R = 0$$ whose solution is $$V= V(t) = V_0 ...
2
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2answers
64 views

Why a tunnel diode (TD) is called a diode?

Traditionally, a diode is a 2-terminal device that limits current to flow in one direction, i.e. a rectifier. But a "tunnel diode", according to wikipedia, is not rectifying: In the tunnel diode, ...
0
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1answer
34 views

What's the difference between tunnel diode (TD) and resonant tunneling diode (RTD)?

According to wikipedia, a tunnel diode is a PN junction whose energies are shifted with bias, while a resonant tunneling diode is a quantum well between a double barrier, whose energies change with ...
2
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3answers
228 views

Rigorously prove that electric field is zero in a perfect conductor

I have ran into a problem while trying to prove that the electric field is zero in a perfect conductor My argument went something like this: We know that: $$\vec J = \sigma \vec E$$ In a ...
2
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2answers
45 views

Does the conductivity of a wire in a vacuum decrease over time?

Does the conductivity of a wire in a vacuum decrease over time, say over the period of years or decades? In other words: Does current degrade a wire, making it less conductive? If so, by how much, and ...
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3answers
362 views

Why does my measured I-V curve for a film of aluminum suggest high resistance?

I plotted the I-V curve between two points (few microns apart) on a thin aluminum film. I expected this metal to be a conductor and have a much lower resistance, but the slope suggests that it is ...