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

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11 views

Half deflection in a galvanometer

Why is half deflection taken while measuring the resistance of a galvanometer? Can't we take deflection in other ratios? Please help.
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1answer
21 views

Calculation Equivalent Resistance In A Circuit With resistances connected in a circle

I am having trouble in finding the equivalent resistance between the terminals 'a' and 'b' in the following circuit: Please can anyone explain to me how to solve such problems. Thank You!
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1answer
31 views

Resistance of a general resistor [on hold]

I have some medium with a resistivity which depends on position. In this material are two electrodes, is there an integral or something which i could numerically integrate to find the resistance ...
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4answers
64 views

Voltage of a battery in a circuit with an infinite resistance [on hold]

I have a dilemma that I would like to share with you concerning batteries (without neglecting internal resistance), emf and resistance of a circuit. To better visualize my question you may need to ...
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1answer
30 views

Help to solve a circuit with capacitor and resistor

Till now I'd never solved a circuit with resistor and capacitor. I'd seen the problem and tried to solve. But now I am in a doubt.The circuit was like that- My attempt-
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0answers
61 views

Resistance is given as mentioned how will we find the equivalent resistance dnt think anyone can do it [on hold]

it is a electric circuit do we have to use ohms law for this question if yes how will we do it
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1answer
52 views
0
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1answer
14 views

Resultant force and constant velocity

Let's say for example, Jack is pushing on a box with force $F$, and John is pushing from the opposite side with force $F$ as well. We say that there is no resultant force, and the box remains stable ...
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2answers
24 views

Using resistance

I want to know the purpose of using resistance. Is it used to Reduce the amount of current? Reduce the speed of the electrons in the wires? For the first reason: Why do we just don't use a ...
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1answer
27 views

Resistance in A.C. circuits

Why do electromagnets offer maximum resistance in A.C. circuits?
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1answer
80 views

Resistor Puzzle [closed]

I was going through physics competition problems on http://fykos.org/ when I stumbled across this one: ... The Square The Joker The electric circuit in the image is made from the infinite ...
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1answer
15 views

Build a device that can set voltage according to intensity of the light shined [closed]

I want to build a device that uses photodiodes and photoresistors to set the voltage in the circuit that shines a bulb. The idea is simple. When the light is intense, the bulb should shine less, when ...
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2answers
34 views

Sign of induced EMF and other elements in AC circuit

I am having problems to determine the direction of the induced EMF in AC circuits. For example, we have an inductor of inductance $L$. The induced EMF is given by: $$ \epsilon = - L \frac{di}{dt} $$ ...
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1answer
39 views

resistance of wires

i have an upcoming open investigation at my school on wire resistance, in preparation for it i want to find out if duct tape would effect the multimeter's readings. i need to connect wire to a ...
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0answers
37 views

How do I find the equivalent resistance of this resistor network? [closed]

I was trying to find the resistance of this network of resistors Until I got stuck at this So, how do I go about from here? Any help would be appreciated. There's just one catch, you are not ...
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0answers
36 views

How to increase Resistance of a conductive material?

I'm working on a project that I should measure the resistance of conductive sample ( like brass ). But I've a problem. Resistance of conductive samples is too low which requires a miliohm meter to ...
2
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2answers
76 views

How to calculate the resistance of a resistors in a grid?

I've found a lot of example of a grid where you want to total resistance of a grid. My problem is different. Let's say you got a grid of resistance (3x3) but you only have the total resistance between ...
3
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1answer
19 views

Why can't we use Meterbridge to measure high resistance and low resistance?

Our physics master taught us that we can't use meterbridge to measure low resistance but he didn't give a valid reason for that.
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2answers
48 views

Input Resistance vs Output Resistance

I am having trouble understanding the difference between these two concepts. I know that input resistance is the resistance as seen by the input terminals and output is as seen at the output ...
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0answers
20 views

How do electrons choose their way through nodes? [duplicate]

Suppose I have a circuit, powered by some emf ($V$). If I put two resistors $R1$ and $R2$ of different resistances in parallel, the current at the node is divided following Kirchhoff's circuit laws. ...
2
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0answers
22 views

Van der pauw method for an isolated hole

Van der pauw method is a way to measure the resistivity of a material with arbitrary shape while it meets some specifications ( being homogeneous and ...). One of the conditions is that the sample ...
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1answer
25 views

Circuit energy evaluation

I saw in a documentary that given a circuit, the electron comes out of the negative side of the battery with some electrical potential energy and upon passing through a resistor it gives up all its ...
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1answer
46 views

What is the condition for resistance in the branch to be parallel [closed]

What if the incoming current at one node not equal to the other, does the resistance in branch still parallel. Eg: In the above circuit diagram how is 17.5 Ω resistor parallel with 5Ω and 2.5Ω ...
3
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1answer
53 views

Effective resistance across 2 adjacent vertices of a dodecahedron with each edge $r$

What will be the effective resistance across 2 adjacent vertices of a regular dodecahedron (12 faces) with each edge having resistance $r$? Here is the source for the problem, it's problem 20. on ...
2
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1answer
44 views

Problem with differential equation RLC circuit serie [closed]

I am trying solve the differential equation of RLC's circuit in serie, I have: $C=4\ F, L= 1\ H$, $R=5\ \Omega$, and $V_e=20\ V$. $1)$ first I got the equation, it is: $i''+5i'+\frac{1}{4}i=0$, what ...
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1answer
36 views

Do resistors have internal energy?

I was reading about LC Oscillations in my book and came upon this: In actual circuits,there is always some resistance and some energy is therefore transformed to internal energy. Why internal ...
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2answers
29 views

Why does current density changes but not current? [closed]

let us assume that we have a conductor with a specified resistance ( case 1 ) and a normal conductor ( case 2 ) as shown in the figure , and now we apply an external electric field with a battery on ...
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0answers
20 views

Potential difference across a resistor

I would like to know if the potential difference between the two ends of the resistance is same as the potential difference between any tow points in the resistance whose length is smaller than the ...
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1answer
46 views

Resistors in parallel - Written description of a circuit - drawing needed [closed]

I can't visualise what this circuit looks like from the description Three identical resistors are connected across a potential difference V so that one of them is in parallel with the other two ...
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3answers
89 views

If we consider the electric field to act upon charges with a force, how does it stay in line with Newton's laws?

This should be a relatively simple question. Let's say we have a constant electric field $\textbf{E}$ in a conductor. The electric current density would then be $$\textbf{j}=\rho \textbf{v}$$ where ...
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1answer
44 views

RC circuit discharging capacitor, trouble understanding

If we apply loop rule while charging the circuit we get: $$\varepsilon -iR-\frac{q}{C}=0$$ The way I understand, we follow trough the circuit just before the battery, as we move trough the circuit ...
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0answers
33 views

Electricity steps/formulae required to answer this [closed]

I need help answering this question and the steps/formulae required. The only answers on my sheet are $0.25V$, $0.75V$, $1.33V$ and $1.50V$ I have worked through it and got an answer of $0.5V$. I ...
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1answer
69 views

Why does an electron lose all of its energy in a resistor?

Why does the electron uses nearly all of its energy for one resistor in a simple circuit made of a battery, wire, and resistor? I really need to know what happens exactly at the atomic level in the ...
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1answer
38 views

Closing a switch in series with a capacitor

Suppose we have the following circuit: Such that for $t<0$ the switch M was open. If we close the switch at $t=0$ what will the voltage on the capacitor, $V_C$, be at $t=0^+$? What about $\dot ...
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1answer
32 views

Current from Middle Battery in a Two-looped Circuit

With this question, as with many tutorials of similar questions I’ve found online, my textbook only mentions three currents: $I_1$, which flows through the left loop from and to the 19 V battery, ...
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0answers
41 views

How does a flex sensor work?

I was reading an article glove controlled hand using flex sensors. I know that a flex sensor is a type of variable resistor, but I want to know it's principle of operation, like does it work on ...
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1answer
32 views

Current through resistors crossing each other [closed]

Calculate the current shown by the ammeter A in the given circuit. I've searched the internet but didn't know how to search for it. Please help
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0answers
18 views

Problems with electronic circuits [duplicate]

While reading electronics,I found two problems. It says to get the equivalent resistance of these two circuits. Please help me saying the process to find the equivalent resistance. Here it is-
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0answers
66 views

Which light bulb will burn out? [closed]

We have 5 light bulbs connected in series assuming all bulbs have identical characteristics. The environment is identical for all bulbs. Wire is superconductor (0 Ohm) and is thick enough to deliver ...
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0answers
24 views

Retardation on a Conducting Object in a Magnetic Field [closed]

I cannot solve this question and I need help to understand the physics. The picture below says it all. What is the retardation (negative acceleration) on the conducting object with a mass of 2.5 kg's ...
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0answers
37 views

What are the first couple terms of the Taylor series for the evolution of this network of capacitors and resistors?

note: This is a computational problem, and I only need approximate accuracy, so the overall goal is, for a given accuracy and $\Delta t$ to compute the state of the system at $t+\Delta t$ to within ...
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1answer
40 views

What is the underlying transport mechanism of electron drift in metals?

The equations involving drift speed, mobility and conductivity, $v_d=\mu E$ and $\sigma=\mu e n$, treat electrons in a Newtonian way. This model works well in practice (at least in macro scale), but I ...
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0answers
21 views

Resistance used to get maximum illumination with proper security

In which way a resistance is to be connected with a bulb labelled 120V-60W when it is connected with 220V DC source so that maximum illumination with proper security is maintained? What is the ...
0
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1answer
26 views

Current in a short circuit [duplicate]

Well,if theoretically we say the value of a resistor is zero then will there be any heat dissipation across the resistor(because heat is produced only when there's a resistance to the flow of ...
1
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1answer
21 views

Why are negative temperature coefficient thermistors accurate for measurements of low temperatures?

Why are negative temperature coefficient thermistors accurate for measurements of low temperatures? How does higher resistance at low temperature accurately measure the temperature?
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2answers
35 views

Will current flow entirely through zero resistance if possible to do so?

I am trying to understand how current splits at nodes. I know that if two paths are available, each with R > 0, a current divider is used to find the split ratio. But what if one of the paths has R = ...
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1answer
41 views

Power Dissipated by Resistor in AC Circuit [closed]

I'm having a problem with the following review question: Given the circuit: I am asked to find the power dissipated by R1 and C. I know that for C it is 0. For R1, I know I need to use Vrms ...
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0answers
22 views

For series LCR oscillations (resonance), why does current have to be maximum?

I learned about a year back that systems will go into oscillations with high amplitudes if the frequency of the forced oscillations coincide with the natural frequency of the system leading to ...
0
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1answer
27 views

What the intensity in a circuit when a generator is off?

Let the following circuit I have to compute $U_{AB1}$ (i.e. $U_{AB}$ when $V_1$ on and $V_2$ is off), $U_{AB2}$ (i.e. $U_{AB}$ when $V_2$ is on and $V_1$ is off) and $U_{AB}$ (i.e. when $V_1$ and ...
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1answer
40 views

How to calculate resistivity of ring [closed]

Q: In a resistance experiment, a gold ring was connected into a circuit as a resistor. The connections touched on diametrically opposite points on the circular ring. Its diameter is 2cm, and the ...