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

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19 views

Solving for currents in a circuit [on hold]

I need help finding the three listed currents in the figure below. Attached on the bottom is the solution for this problem, however I do not quite understand how they came up with the answers. ...
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0answers
21 views

Unsure how resistors are connected? (Series/Parallel) [duplicate]

I am currently attempting this practice question in my tutorial and while I am able to reduce the circuit below to I do not know whether the 6/6/6/6 pane is connected in series or parallel, it ...
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1answer
42 views

Resistors in para and series circuit, finding volt [on hold]

How anyone know how to do the question? I know how to reduce it to a window pane of 6/6/6/6 with a 3 in series but i have no idea how to do it. Well i did manage to reduce the right side of the ...
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0answers
27 views

Solve the following linear second order circuit [on hold]

I am not able to solve for the second part of the question (when v(t) = 0)
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2answers
17 views

Direction of current in concentric cylinders

Example 7.2 in David Griffiths E & M book (3rd edition) has a side view of 2 concentric cylinders, with smaller radius $a$ and larger radius $b$. The region in between $a$ and $b$ has ...
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0answers
42 views

Electricity Problem [on hold]

A power Station Is Connected To A Factory 2.5 km Away By Two Wires the potential difference between the terminals of the wires at the station is 240v and that for the other terminals at the factory ...
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1answer
51 views

Resistance and amperage [on hold]

My problem is to solve the following exercise. First, if $R1 = R2$, then $I1 = 1.0\,\text{A}$. Now I have to find $I1$ if $R2 = 2 R1$. If $R1 = R2$ then I have got for the total resistance ...
2
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1answer
51 views

Kirchhoff current loop in Resistor Diode Ladder network

I am looking for an approach on how to apply Kirchhoff current / voltage law in the infinitely long diode ladder network. Can anyone help me with this ? I am looking for 1D differential equation or ...
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2answers
24 views

potential difference in parallel connecting resistors

How could the potential difference be constant across all the resistors of parallel connecting resistors although each resistor has a specific resistance?
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3answers
66 views

How does Ohm's law apply to superconductors?

As radio amateurs we've all learned the various relationships of power, voltage, current and resistance as expressed in Ohm's Law. My question relates to the following simple circuit showing an ideal ...
2
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2answers
56 views

Difference between $I^2R$ and $V^2/R$ and $VI$ for measuring power $P$

We use $I^2R$ or $V^2/R$ or $VI$ for measuring power $P$. Are all of these applicable for all circuits? I have seen in some circuit $V^2/R$ is not equal to $I^2R$. Why is that?
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2answers
26 views

Energy stored in a capacitor in an RC circuit

Suppose we have a capacitor of capacitance $C$ and a cell of emf $E$, why is the maximum energy stored in a capacitor equal to $\tfrac{1}{2}CE^2$? I feel confused because, the potential difference ...
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2answers
37 views

Can current and resistance result in establishing voltage?

I want to know whether current & resistance can cause a voltage across the circuit, according to Ohm's Law $V=IR$. Is it possible to use a low current to produce a high voltage?! How can this be, ...
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1answer
40 views

Why does magnetic field increase when the number of coil turns increase?

Since we all know that to increase the magnetic field we can do these of the following things: (i) Increase the number of turns in a coil, (ii) Increase the current following through conductor, and ...
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2answers
34 views

Increasing resistance, by heat?

I was wondering the magnitude of effect to a conductor's resistance when heated by a few degrees. Can this be controlled way of changing conductor's resistance, or fixing in a system?
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1answer
21 views

Calculate the current in mA which will be flowing through the two resistors [closed]

Three resistors of 3,4 and 5 ohms are joined in parallel in an electric circuit. If a current of 150mA flows through the resistor of 4 ohms,then calculate the values of the current in mA which will be ...
2
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4answers
75 views

Why does a Resistor cause a potential drop?

I need to know the underlying physics of what exactly happens different with the electric field in the resistor than in superconducting wires. Why is it that when I connect a resistor, potential ...
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4answers
96 views

Ohm's Law: Drude Model

For a very long time now, I've been thinking about the Drude Model derivation of Ohm's Law. I know that a rigorous derivation requires a Quantum Mechanical approach. However, the mere fact that the ...
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0answers
12 views

Why is low resistance beneficial to ion exchange membranes?

http://scitation.aip.org/content/aip/journal/jcp/139/11/10.1063/1.4821161 The article states that the graphene filter has a much lower electrical resistance than existing ion exchange membranes, ...
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3answers
84 views

Why does resistance increase with length?

This is for the case of wires only (pipes are easy). I see that if I place a 9-Volt (constant) battery across any wire, the current is proportional to resistance. I don't understand why, for a ...
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1answer
88 views

Why isn't resistance proportional to distance squared

Here we have a wire. At both ends there is an equal and opposite field caused by a chemical reaction. So, if we decrease or increase the distance between the two points, the strength of the field ...
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4answers
454 views

Why does a short circuit generate fire?

When a short circuit occurs it's obvious that there is fire. How come electric energy turns out to be heat energy? What causes the conductors to get hot when short circuit is present.
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0answers
67 views

Q factor of parallel RLC circuit in series with a capacitor and resistor

I know that for parallel RLC circuits, the $Q$ factor is given by: $$ Q = R \sqrt {\frac{L}{C}} $$ But now suppose it is connected in series to a resistor $R_2$ and capacitor $C_2$. Would the $Q$ ...
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3answers
61 views

What really is resistance? How does it generate heat?

OK I know that R= V/I. I also know that R = ρl / A But what I want to know is that what really causes resistance? Is resistance equivalent to force? or is it just a constant? Also, what causes ...
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0answers
13 views

Contact resistance copper-silver

I need to determine the contact resistance of a copper silver interface. The copper wire was soldered to the substrate using an IR-Laser. I was wondering if I can treat the entire system as a series ...
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1answer
56 views

Simple Parallel Electric Circuit [closed]

Ammeter (A1) and voltmeter (V) in series have parallel connection to another ammeter (A2). Currents in A1 and A2 are respectively 0.2 and 1.7 amp. Voltmeter's voltage is 6 volts. How should I find ...
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3answers
79 views

Could this open electric circuit work?

Two batteries are interfaced by a resistor. Parameters such as resistance can be set arbitrarily. Does it work?
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0answers
36 views

Alternate solutions to Resistance of a Conical Frustum

Since for a cylinder R=p(length)/(Area) I assumed an equation of radius of this frustum radius=a+((b-a)/length)*x and then integrated to get the answer Are there other ways to find the ...
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1answer
74 views

Interpreting Physics Results Regarding Circuitry Analysis (Highschool Level Physics) [closed]

I conducted an experiment which aimed to detail and record the voltage across series resistors in series circuits. I noticed that: The Final Voltage, V3, stayed the same. The resistors with the ...
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0answers
32 views

Temperature coefficient of resistivity (resistance) in function of temperature

If I'm correct, the definition of the temperature coefficient of resistivity at a certain reference temperature is the derivative of the resistivity in function of the temperature, divided by the ...
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2answers
209 views

How is the current same on both the sides of a resistor?

I am wondering that how can current be equal on either side of a resistor as the work of a resistor is to resist the flow of electrons i.e. decrease the current. How is this possible?
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1answer
41 views

Finding resistance [closed]

Two resistors when connected in parallel give the resultant value of $2\,\Omega$, when connected in series the value becomes $9\,\Omega$. Calculate the value of each resistance.
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1answer
168 views

How to find percentage error of equivalent resister? [closed]

The resistors of $R_1=100\pm3Ω $ and $R_2=200\pm4Ω $ are connected in parallel.Then express equivalent resistance with percentage error. I know how tho find percentage error if resistors are ...
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5answers
150 views

Ohm's Law Intuition

When we derive Ohm's Law using the Drude Model, we assume at one point of time that $E=V/L$, when is fact, $E=dV/dL$, unless $E$ is constant, in which case the assumption $E=V/L$ is true. But I don't ...
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2answers
104 views

Having trouble understanding the concept of current and Ohms law

Circuit in series: $10\,\text{V}$ power supply, 2 resistors connected. Each resistor is $10\,\Omega$, total of $20\,\Omega$ resistance. If I put an ammeter at the end of the circuit, will the current ...
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1answer
57 views

Ohms law and multiple resistors

In my physics class, we did an experiment in which we supported Ohm's law. We used a simple circuit that includes one resistor. The relationship of I = VR, and variants thereof, became apparent. We ...
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3answers
59 views

Resistor and LED - together and separated

Something very basic which I don't get no matter how much I read. circuit A: only a resistor and power supply - the resistor will burn. circuit B: only a LED and power supply - the LED will damaged. ...
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0answers
12 views

Equivalent resistance of an infinite square mesh [duplicate]

Consider an infinite square mesh of resistors each of resistance $1 \Omega$. Calculate the equivalent resistance between two diagonal points on a single square.
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1answer
269 views

Relative error of equivalent resistance of resistors in parallel

I just saw a formula in my book for relative error in equivalent resistance of two resistors connected in parallel. $\frac{\Delta R}{R^2} = \frac{\Delta R_1}{R_1^2}+\frac{\Delta R_2}{R_2^2}$ ...
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0answers
29 views

Comparing Graphene and Ni3 HITP2

A recently announced advance in Metallized Organic Films at MIT: http://pubs.acs.org/doi/abs/10.1021/ja502765n discusses a self-organizing material: Ni3HITP2 = ...
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1answer
132 views

How can rheostat change the current without changing int voltage

NCERT science of 10th, in chapter electricity on page 205, there, a is line written: a component use to regulate the current without changing the voltage ...
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2answers
152 views

A confusion in ohms law $V = IR$

ohms law clearly states that potential difference is directly proportional to the current flowing through the wire or V directly proportional to I ______(i) so the formula which is ...
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2answers
435 views

Proof of Thevenin and Norton theorem

How can I prove Thevenin's and Norton's theorem? Thévenin's theorem can be used to convert any circuit's sources and impedances to a Thévenin equivalent.
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2answers
53 views

Other units of resistance [closed]

Resistance is $\frac{V}{I}$, and we get the unit $\Omega$. Another unit is $\frac{W}{A^2}$. How do you derive that unit?
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1answer
50 views

Do I understand impedance correctly?

$$Let\quad \vec { Z } =R+Xj$$ If $X>0$,then the impedance is lagging (current lags behind voltage).If $X<0$, then the impedance is leading (current leads voltage or more accurately, voltage lags ...
14
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4answers
1k views

What's the physical meaning of the imaginary component of impedance?

As you know, impedance is defined as a complex number. Ideal capacitors: $$ \frac {1} {j \omega C} \hspace{0.5 pc} \mathrm{or} \hspace{0.5 pc} \frac {1} {sC} $$ Ideal inductors: $$ j \omega L ...
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1answer
48 views

Thermal resistance of thermal interface materials?

Thermal conductivity are often used for surfaces between the computer chip and the heat sink to increase heat transfer and they want high thermal conductivity to decrease the thermal resistance. By ...
2
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0answers
28 views

How do I determine resistivity from electron defects of high purity gold?

I am trying to create a plot for the electrical resistivity of high purity gold from 1 K to 1000 K. I found gold's resistivity at 300 K using the Wiedemann-Franz Law based on thermal conductivity data ...
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1answer
52 views

Circuits and Power

"The diagram below represents a simple circuit composed of 5 identical light bulbs and 2 flashlight batteries. Which bulb (or bulbs) would you expect to be the brightest? a) V only b) V and W ...
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3answers
185 views

If the current is increased, is there more charge flowing or is it moving quicker?

Problem Current is the amount of charge that is flowing through a component per unit of time. For a given voltage, Ohm's law tells us that if we increase the resistance, then the current must ...