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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0answers
18 views
RC circuit Laplace Transform [on hold]
I've got the equation for RC circuit:
where F[s] was initially $e(t) = V_{0} sin(ωt)$ before Laplace Transform. How to calculate function $V_{2}(f)$, where $f$ is the frequency?
-2
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0answers
16 views
What is the current in the resistor X? [on hold]
A combination of four identical resistors each of resistance R are connected to a source of emf ε of negligible internal resistance. What is the current in the resistor X.
0
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1answer
24 views
How does the thickness of a sample affect the accuracy of four-point probe resistance measurements?
I have been reading up on my experimental techniques, and I found a description of four terminal sensing here. It makes the statement that for accurate measurement of resistance the thickness of the ...
0
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0answers
10 views
Operational amplifier characteristics [on hold]
What are the differences between the Open and Closed loop gain of an operational amplifier? Also, what is the concept of “feedback resistance” in amplifiers?
0
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2answers
46 views
Impedance of an LCR circuit
So I am trying to understand how to find the impedance of the parallel LC component of this filter circuit. I am given that the transfer function $\mathbf{T}_C = \dfrac{\mathbf{V}_{out}}{\mathbf{V}_{...
0
votes
1answer
28 views
Overestimation Problem [duplicate]
I had asked this problem earlier but I was too vague in how I asked it so I'm making a new post to be more specific.
Problem: Say we have a series circuit with an ammeter, a cell with internal ...
0
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0answers
24 views
Calculation of Resistance in an isolated wire of 8 shape [closed]
Exercise:An isolated wire is used to construct a circuit in 8 shape composed of 2 circles. The superior circle has a radius of 5cm and a inferior circle has a radius of 9cm. The wire's resistence per ...
0
votes
1answer
26 views
When the external resistor increases in temperature, why is the calculated value for internal resistance higher?
Say we had a circuit with a cell (with internal resistance)and an external resistor of 10 ohms as shown:
The 10 ohm resistor then increases in temperature, leading to an increase in resistance in ...
1
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5answers
83 views
Why does the potential difference across a type of parallel circuit not act like a potential divider?
Image credit (Q3)
In this attached circuit, when $R_1=0\Omega$, I am failing to understand how the two cells affect the potential difference across the central resistor R3. I understand that ...
0
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3answers
66 views
Voltmeter reads zero with two same batteries connected in series [closed]
this is an a level physics question, can someone here please explain why voltmeter reads zero and how changing resistance of variable resistor effects voltmeter reading.
The main concept i want to ...
0
votes
5answers
80 views
If current through a resistor is zero, does the circuit break?
I'm really confused. I'm studying about how capacitors are charged, and I learnt that there's a resistor attached in series with the capacitor when it is being charged. When the capacitor is fully ...
1
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0answers
12 views
Photoresistor in Parallel [closed]
I am currently building a photoresistor from a kit that I bought a few months ago. I had a few questions when I was building this circuit:
What happens when you wire the photoresistor in parallel ...
0
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0answers
27 views
Question about current density
I was looking at past exam papers and found a question that I can't understand. It is basically about current flow but the diagram is really confusing me. The diagram is the following:
The question ...
0
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0answers
50 views
Proof of Ohm's Law [duplicate]
I was watching MIT OCW 802 and the lecturer mentioned that Ohm's law has a proof by quantum mechanics. Can someone please explain this.
40
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3answers
12k views
Will the volt, ampere, ohm or other electrical units change on May 20th, 2019? [duplicate]
When watching a video by Veritasium about the SI units redefinition (5:29), a claim that the volt and unit of resistance (presumably the ohm) will change by about 1 part in 10 million caught my ...
0
votes
1answer
44 views
Evaporating tungsten wire
Consider an incandescent bulb having a thin filament of tungsten that is heated to high temperature by
passing an electric current. The hot filament emits black-body radiation. The filament is
...
2
votes
1answer
52 views
What is the cause of resistance?
I searched for this question on the internet but didn't got a satisfactory explanation.
What I thought on the topic is that the cause of resistance is 'the effective nuclear charge'. The nucleus ...
0
votes
3answers
42 views
Current Divider rule
If you have two resistors $R_{A},R_{B}$ connected in parallel with a battery, you can find the current that flows through one resistor ex.$R_{A}$ using the current divider rule:
$$I_{A}=\frac{V_{T}}{...
0
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0answers
35 views
Estimating the effect of inductors in an RL circuit
I'm trying to understand how an inductor works in an RL circuit. When I use an air core inductor, my estimation is fairly accurate to the test circuit but as soon as I use an inductor with a core, the ...
1
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1answer
99 views
I got this formula but can anyone prove it [closed]
Yesterday while doing some questions, I came across a formula that if a wire with uniform resistance R is made into n sided regular polygon then the net resistance between any two corners with $x-1$ ...
4
votes
2answers
100 views
Why does electrical resistivity have units of $\Omega \cdot \mathrm{m}$ rather than $\Omega \cdot \mathrm{m}^3 ?$
Electrical resistivity has units of $\Omega \cdot \mathrm{m} .$ However, since resistivity can be described as the resistance of a unit cube, shouldn't the units therefore be $\Omega \cdot \mathrm{m}^...
1
vote
1answer
64 views
Does the voltage of the battery change if you use it? [closed]
If you use the battery to charge a capacitor does the voltage of the battery decrease or still the same? Does the voltage of a capacitor decrease if you use it to charge another capacitor?
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votes
3answers
105 views
How does resistance affect the voltage drop? [closed]
There is a series curcuit and there are 5 resistors in it which are the light bulbs. I know that current is directly proportional to the voltage and inversely proportional to the resistance. Can ...
0
votes
2answers
45 views
Parallel circuits at home
My textbook states that if you have a light bulb turned on and you connected a hair dryer with it in parallel, then the brightness of the light bulb will decrease.
The reason my textbook provided, ...
1
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4answers
72 views
Inductance in superconducting wires (and the math)
I'm very curious about inductors in general, and how similar they are to capacitors.
In the above picture the formula of current over time in an inductor with wire resistance $R$ is written.
I'm ...
0
votes
2answers
73 views
Why I can't find a value for the resistivity of plastic? [closed]
I'm working to a relation about resistence of various materials. I haven't found a table of resistivity wich includes Plastic. Is searching plastic too general? Does a table in which there is at least ...
0
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0answers
31 views
How is energy transferred to a resistor in an electric circuit?
I'd really appreciate some help understanding this.
I've always thought that in a circuit, some source of potential (such as a battery) accelerates the electrons in the circuit, and that collisions ...
0
votes
1answer
23 views
How is current affected by a charging capacitor in parallel to a resistor?
Imagine a circuit with a battery followed by a lightbulb and an uncharged capacitor in parallel. Next to it is an open switch. When I close the switch completing the circuit, does the brightness of ...
1
vote
2answers
57 views
Current in the inductor at $t=0$
$L_1 = 5H, L_2=0.2H, M=0.5H, R_0=10 Ω$, and $i_g=e^{-10t}-10 A$. I need to find $i_2$.
I've started with DE
$$i_2R_0+L_2(di_2/dt)+M(di_g/dt)=0$$
and solved it for $i_2$, so $$i_2=0.625e^{-10t}+Ce^{-...
1
vote
3answers
57 views
When high voltage leads to low current in power transmission system how its not applicable for household voltages?
When high voltage leads to low current in power transmission system using transformers,how increase in voltage in household circuits from 220 volts makes the current increase damaging the appliances,
...
2
votes
2answers
88 views
Parasitic capacitance in real resistors
Typically, I'd assume (A) is only a justifiable answer when the two metal end caps have essentially infinite area, or when the spacing between end caps is far smaller than their respective areas, in ...
-1
votes
2answers
48 views
Power in Series and Parallel circuits
My textbooks states that the brightness of a light bulb that is connected in a circuit is determined by its power. That is, a light bulb connected in series would be brighter if it has a higher ...
1
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2answers
48 views
What should be the independent variable in a resistance experiment?
I was asked a question by a student today and I have been pondering about it for a while now. In an experiment to measure resistance of a conductor, should we vary voltage across the conductor and ...
-1
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0answers
24 views
Current through lamp when an extra component is added in the circuit
I cant figure out part ii. (the lamp is the X)
I calculated the total current in the circuit, which increased to 10.24A. thus, the voltage drop increased and voltage across the lamp decreased to 11....
1
vote
0answers
23 views
$j$-$\omega$ method alternating current circuit help [closed]
I'm suppose to calculate the current and the phase angle. Can someone please tell me if this is the correct solution?
0
votes
1answer
49 views
How does the $I$-$V$ curve for bulk metal look like?
For semiconductors, the current (I) vs. voltage (V) relationship is as shown in the picture below.
As we increase the applied voltage, the electron-hole pairs generate increases too, so we see an ...
0
votes
4answers
37 views
Finding the charge on a capacitor (RC circuit)
I am having trouble finding the charge on the capacitor for $t\rightarrow \infty$ after the switch has been closed at $t=0$. I already know the current $I$. I also have to find out on which sides the ...
2
votes
1answer
64 views
Resistors parallel to short circuit
I have a trouble solving this problem.
(Actually, each resistor is not parallel with the bottom wire since the voltage across each of them is different with that of wire.)
In the manual, the bottom ...
0
votes
1answer
28 views
Why isn't $V_L$ not equal to $i_LR_L$ according to Thevenin's theorem?
According to Thevenin's Theorem $I_L= \frac{V_{th}-V_L}{R_g}$ whereas $I_L$= current through the load. $V_{th}$= The potential difference across the load resistance when the load resistance is ...
44
votes
13answers
9k views
What *exactly* is electrical current, voltage, and resistance?
I am taking AP Physics right now (I'm a high school student) and we are learning about circuits, current, resistance, voltage, Ohm's Law, etc. I am looking for exact definitions of what current, ...
1
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1answer
55 views
How do resistors form electric fields and thus potential drops?
$$V_{ab}=-\int_b^a\vec{E}*\vec{dl}=\int_a^b\vec{E}*\vec{dl}$$
By Kirchhoff's loop rule, the sum of the potential drops across a closed loop is zero. Going in the direction of conventional current ...
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votes
1answer
39 views
Please tell me how to solve star resistance network [closed]
Please tell me how to solve star resistance network
I have tried solving it, but the connection between the crossed resistances is confusing me.
0
votes
1answer
29 views
Thermal dissipation and local Ohmicity of nonlinear components
In this answer, it was established that Onsager relations make a one-to-one correspondence between the linear relationship between voltage and current, and entropy creation rate in the electric ...
1
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1answer
16 views
Relationship between concentration and resistance of aqueous solutions
I'm a senior physics/chemistry student working on a practical assignment where I am trying to identify the resistance of CuSO4 in solution (distilled water). I have recorded my data and determined it ...
0
votes
1answer
28 views
How to distinguish the radius from the electrical or thermal resistance? And how to distinguish thermal resistance from electrical resistance?
We know both the electrical resistance and the thermal resistance of a cylinder is inversely proprortional to the square of the radius of the cylinder. But the letters R and r are used sometimes for ...
0
votes
2answers
34 views
What will happen if an ideal current source is connected to a isolated resistance?
I know that ideal current source is a theoretical thing. But when it comes to solve problems we have to consider these scenarios. Now suppose an ideal current source is connected with an isolated ...
0
votes
1answer
99 views
Would Kirchhoff’s rules not hold in this circuit?
On my E&M test I was given the circuit diagram below and asked to find the charge on the capacitor after a long time or as $ t \to \infty $. In class we had used Kirchhoff’s voltage rule on the ...
1
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1answer
30 views
Thermistors and their resistance
I take GCSE physics and I'm having difficulty understanding how resistance and temperature link with one another. I've been taught that the greater a component's temperature, the greater the KE of its ...
0
votes
1answer
60 views
Why does my finger not conduct electricity when I press on my laptop case?
I have an aluminium laptop and when it is plugged in and I brush over the case I feel a small tickeling when brushing lightly on the case. I have read that is coming from grounding issues and this ...
0
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0answers
27 views
Resistivity of dielectric liquids
I was wondering if anyone here knows how the resistivity values of highly resistive dielectric liquids have been determined since the best commercial conductivity sensor I can find online only ...
