Tagged Questions

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

21 views

Short circuit due to loose terminations

I have been reading into wiring and circuits and found someone post that they had a circuit breaker tripping because of a loose wire in the circuit. They claimed the hot screw/lug combination ...
23 views

Half deflection in a galvanometer [on hold]

Why is half deflection taken while measuring the resistance of a galvanometer? Can't we take deflection in other ratios? Please help. I meant to ask while taking out the shunt resistance, why do we ...
33 views

Calculation Equivalent Resistance In A Circuit With resistances connected in a circle [on hold]

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!
32 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 ...
66 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 ...
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-
65 views

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

it is a electric circuit do we have to use ohms law for this question if yes how will we do it
56 views

The equivalent resistance betweeen A and B. I need the answer with proper explaination [closed]

how are we supposed to do this question if resistance is given as 1 ohm
15 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 ...
25 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 ...
28 views

Resistance in A.C. circuits

Why do electromagnets offer maximum resistance in A.C. circuits?
81 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 ...
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 ...
35 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: $$\epsilon = - L \frac{di}{dt}$$ ...
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 ...
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 ...
78 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 ...
25 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.
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 ...
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. ...
23 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 ...
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 ...
47 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 ...
56 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 ...
45 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 ...
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 ...
30 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 ...
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 ...
48 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 ...
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 ...
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 ...
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 ...
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 ...