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Questions tagged [electrical-resistance]

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

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2answers
43 views

Is it correct to say that a smartphone cable is only a “1A” cable?

A store owner said that some lower quality smartphone charging cables are only "1A cables", so if you want 2A, those cables won't do the job. Is it correct to say a cable is only 1A? Does the metal ...
1
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4answers
87 views

How does resistance *really* work? (DC, battery, LED, atoms, electrons)

Backstory: I’m a software engineer just getting into electronics and it seems that everything I’ve ever been told about electricity my whole life is a candy-coated lie. I can’t find consistent logical ...
-1
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0answers
23 views

Resistance of a hollow cylinder [on hold]

So there is a hollow cylinder with inner radius a and outer radius $b$ material is present between $a$ and $b$. its resistivity is $\rho*P$. Its height is $h$. A time varying magnetic field is present ...
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1answer
37 views

Skin effect prevailing the drift velocity effect

In general, an electron will propagate randomly in a conductor at the Fermi velocity( produced due to thermal energy of the conductor). An applied electric field will give this random motion a small ...
-1
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1answer
25 views

Potential divider

I am just wondering if a potential divider circuit is used to vary the pd across the other resistor from zero to maximum, why can't the variation be done straight from the source?
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3answers
51 views

Non-ohmic conductors

Non ohmic conductors are said to be the conductors that do not obey Ohm's Law. The V-I graph for them is not a straight line unlike ideal ohmic conductors. According to me Ohm's Law states: The ...
3
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1answer
41 views

Does the cold affect electrical conduction?

Disclaimer: I'm not experienced in many phyiscal nor electrical terms and I have no idea where to ask this question elsewhere. I'd be open for a move request if needed. Today when using public ...
-1
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0answers
21 views

Need help in circuits [on hold]

So I m not a undergrad student yet and I have some difficulties while measuring the equivalent resistance of a circuit. Specially from those complicated diagrams and so on. So I deadly need advise in ...
0
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1answer
24 views

AC circuit with resistor

As you can see from the image that "potential drop must be equal to the applied emf". This means after that point there is no flow of current as potential difference is zero.But how is this possible?...
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0answers
20 views

Kirchoff's rule DC circuits [closed]

I understand how to solve for the unknown variables but I have trouble labeling the currents and finding the current and junction equations
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0answers
10 views

Finding resistance and how many appliances can be connected

A household electricity system can be modelled as a fuse in series with appliances, all of which are in parallel across the 240V mains supply. In one household there is a 16A fuse in series with the ...
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0answers
24 views

Finding resistance when given amperage and voltage [closed]

Question: A household electricity system can be modelled as a fuse in series with appliances, all of which are in parallel across the 240V mains supply. In one household system, there is a 16A fuse ...
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6answers
49 views

Why doesn’t current decrease when it passes through a resistor?

As far as I know current is the amount of charge passing per unit time. $$I=q/t$$ When current passes through a resistor, the resistor resists the flow of current so the amount of charge going to ...
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1answer
26 views

Why is the open circuit voltage equal to Thevenin's Equivalent Voltage?

When we are taught Thevenin's Theorem, we are taught that the equivalent voltage Vth is the voltage obtained at terminals A-B of the network with terminals A-B open circuited. But why is it true?
2
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3answers
57 views

Calculating uncertainty when combining parallel resistors

A recent question asks students to calculate the total resistance of parallel resistors R1 and R2 with uncertainty. R1 = 120 Ω (+/-10%). R2 = 500 Ω (+/-10%). We would normally use the ...
0
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2answers
56 views

Charging and discharging a capacitor [closed]

So from what I understand, in the case for the charging capacitor, I understand the voltage across the capacitor as well as the charge can be given as the function of time: $$V(t)=\epsilon(1-e^{-t/RC}...
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2answers
51 views

RC circuit confusion [closed]

I was doing some RC problems in A levels, and in ine of thr problems it was about a circuit attached as a picture: My question is can someone clearly explain to me why when time goes to infinity , ...
0
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1answer
20 views

I am trying to understand wire gauge size vs current flow?

I am trying to understand how wire gauge size relates to the current that will flow through it. Lets say we have a 100 foot long, 16 gauge extension cable made internally of copper wiring. After ...
0
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2answers
51 views

How is a capacitor implemented in Kirchoff's Loop Rule?

I'm real stumped here. I may be missing something, but I'm genuinely perplexed as to how one would add a capacitor to the list of elements being added to an equation through Kirchoff's Loop Rule (KVL)...
1
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1answer
49 views

How do we measure the age of the universe? [duplicate]

How do we measure the age of the universe if time is relative to the observer? What is the reference frame we use to measure the age of the universe?
1
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0answers
76 views

Elementary argument that Ohm's law is nonclassical?

The freshman physics texts that I have to hand (Purcell, Feynman lectures) seem to invoke Ohmic behavior of materials without explicit justification in terms of microscopic models or experiment. ...
9
votes
4answers
1k views

How do I deal with “crossing resistances”? [closed]

I'm doing some physics homework calculating the total resistance between points A and B and while some circuits are comprehensible, there are two that I can't understand how they work at all. So, it ...
0
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0answers
18 views

Best method for determining tolerances based on production data [migrated]

Say I am producing a wound coil which is ultimately going to be used in a colpitt's oscillator circuit. I measure the Ls and Rs of the coil, and then install it in a ferrite and then test it in the ...
0
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1answer
54 views

Shouldn't there be short circuit everywhere?

Live wire and neutral wire should never come in contact otherwise there will be a short circuit... but when we take a two pin plug and insert it into the socket then at that time we don't see whether ...
2
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2answers
76 views

What is the equivalent resistance between $A$ and $B$ in the given circuit? [closed]

Hi, I've been doing some current electricity problems by using Kirchhoff's laws. I've tried applying KVL(Kirchhoff Voltage law) to this circuit, but to no avail. There happens to be too many variables ...
0
votes
2answers
17 views

Principle of potentiometer

I could not understand why the emf of the main cell (labelled E) in the circuit (can be a battery eliminator) should be greater than the emf of the cells (E1 and E2) used in the secondary circuit. ...
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1answer
42 views

Is there any way to determine how long a wire is?

This is for transmission lines applications. Are there any way to know how long the wire like by getting the resistance of the wire(but how). Or is it possiblee to charge the wire until it produces ...
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3answers
52 views

Ohm's Law and transmission of electricity

Electricity is transmitted at high voltages. It is said that this reduces current and consequently resistance. But according to ohms law, low current must face high resistance. How is this ...
0
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0answers
6 views

BJT as a switch: what am I doing wrong? [migrated]

I'm studying the following circuit The image is explicit but as you can see the input measured in the upper terminal is a square wave with $E_c$ and $-E_c$ as levels. Now I also had no trouble ...
1
vote
1answer
31 views

How can Resistance be transferred across in a Transformer?

Can someone tell me how the resistor could be transfered from the secondary to the primary side? Could you give me a concise explanation on how it's possible? A simple analogy/analysis would be very ...
2
votes
0answers
19 views

What's the explanation for Kohler's rule?

In a metal, the increase of resistivity ($\Delta\rho$) due to an applied magnetic field follows a functional form of the parameter $\rho_0/B$ (residual resistivity divided by magnetic field) i.e. $$(\...
0
votes
1answer
27 views

What skills are required to deal with almost every DC problem? [closed]

What skills do you recommend me to learn so that i can deal with almost every DC circuit problem and simplify any combination of resistors regardless how complex is it? Surely there's nothing magical ...
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0answers
22 views

Find the equivalent resistance between points a and b. Please explain in detail how u solved it [duplicate]

Find the equivalent resistance between points a and b. Please explain in detail how u solved it.. Please help me.
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votes
1answer
65 views

Are these two circuit equivalent? [closed]

are the two circuits equvalent ? I have actually got a different problem (wheatstone bridge) but,I want to make sure that there is no mistake in my assumption before asking that question. In the ...
0
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4answers
66 views

Potential Difference of a battery - What does it mean?

I have studied current electricity for a while now. When I look back at basic concepts, I am quite clear about what current, electron, resistance is. But I cannot imagine about the potential ...
0
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2answers
51 views

Potential difference of resistors in parallel linked systems

Before the question I want to explain somethings to see if I understand anything wrong please tell me if im wrong: When there is a Potential difference on a system then the electrical charge will move ...
0
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1answer
11 views

Percolation of electrical conductivity

When a metal is made of different conductivity parts, current passes the least resistive percolation path. My question is “does this path depend on the amount of current?” I think the path doesn’t ...
0
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1answer
39 views

Will there be an induced EMF if the windings have no resistance?

Imagine a transformer, the primary has a voltage source, a 5 Ohms resistor, and obviously the windings too. If there were no resistance on the windings will there be any emf induced on the secondary ...
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1answer
73 views

Question about circuit with two cells [closed]

Edited - could someone explain how you treat a circuit with two cells in respect to circuit laws and also whether the section in the middle is in parallel or in series. Second Edit: I’ve researched ...
1
vote
4answers
106 views

What is the resistivity of solid non-metallic hydrogen?

If I were to use solid hydrogen (assuming temperature of 10K, pressure 1 atm) as a resistor of sorts, what would it's resistivity be? (Note: If someone can give me a good resource on info like this ...
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0answers
29 views

Book on heat generated in a circuit

Can someone suggest me a book with tough quality questions on heat generated in a circuit like in rc,lr circuits etc.
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4answers
99 views

How to understand Kirchhoff's Voltage Law?

I'm having a hard time trying to understand why Kirchhoff's Voltage Law is true. I looked for an answer on the forum but I couldn't find a convincing one. So my question is : How to "physically" ...
2
votes
2answers
113 views

Now what will happen in this circuit?

Consider a circuit as shown in this figure below- Assuming switch S1 is closed such that current flows in loop ABCDE for a long time and steady state is reached. Now, my question is simple, suppose (...
1
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1answer
43 views

Why is a parallel RLC circuit usually driven by a current source?

Almost always when I see an example of a parallel RLC/LC circuit diagram online, the circuit is driven by a current source instead of a voltage source. On the other hand, the series RLC is always ...
0
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4answers
73 views

How is energy conserved in a theoretical circuit where you put a lightbulb and two rechargeable batteries like… (diagram included)

In the beginning the first battery is fully charged, and the second is fully discharged. As the circuit is connected the discharging battery recharges a dead second battery and light is emitted from ...
0
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1answer
25 views

Does the current lose kinetic energy , potential energy, or a combination of the two?

When an electric current passes through a resistor , the current loses energy, transferring thermal energy to the resistor. Does the current lose kinetic energy , potential energy, or a combination of ...
0
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0answers
20 views

How to derive reflected waves in AC circuit?

I was reading the wikipedia page "Reflections of signals on conducting lines". In the section "Arbitrary impedance" they consider a circuit consisting of an alternating source $2V_i$ and two ...
0
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1answer
23 views

Is the magnetic field cancelled out in a transformer?

https://physics.stackexchange.com/a/153501/213243 In the 3rd paragraph it is said that the magnetic field from the primary windings is cancelled out by the induced current from the secondary windings....
2
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0answers
30 views

Would there be any current if an electric circuit is cooled to absolute zero?

My question is if I got a superconductor and cool it to absolute zero at least measurable by today's tool, it should have no electrical resistance but then would there be any current when there is a ...
1
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2answers
33 views

Voltage across parallel resistances

A resistor is connected to a battery of certain potential difference, it has now $V$ volt potential difference across its ends, after some time a resistor is connected in parallel with it. How does ...