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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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Orientation of resistor when connected in a cicuit

Consider a cuboid shaped resistor. Now Case1: Connect the resistor along is length to a battery. Case2: Connect the resistor along is breadth to a battery. In the two cases the length and cross-...
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0answers
28 views

Homework question [on hold]

A steady current passes through a wire even when it’s cross-sectional area decreases as shown in the figure below. Compare each of the following quantities for region A and region B: a) net charge ...
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1answer
40 views

Resistance and temperature relationship

When the temperature changes from $\theta_1$ to $\theta_2$, having $\alpha$, and the amount of resistance ($R_1$) in the previous temperature ($\theta_1$), we can calculate $R_2$, the amount of ...
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1answer
49 views

Calculating electrical resistivity of a material

If I plan to measure the resistivity of a high resistivity material, would it not make sense to alter the geometry of the sensor to make A/l as small as possible and reduce the voltage to get a low ...
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1answer
25 views

Combining two power sources to get voltage from one and current from another

For a project, I have to make a battery that output 5 V, 500 mA. However, each one of my cells can only produce 1 V, 80 mA. I can combine these cells in series and parallel to get the required ...
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2answers
55 views

Why does current always go to the resistance which is lower? [duplicate]

Why does current chose the easy way? Is there a proper mathematical formula about why current tends to go over a resistance which is smaller?
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1answer
66 views

What is complex frequency? [on hold]

I am learning EE, and about complex frequencies, but what is its physical meaning? What is it used for? Why is it? And only happen in the laplace transform?
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2answers
65 views

Resistance of an object with arbitrary shape

Suppose to have a conductor with a non-trivial geometry, like the one in the picture: The shape does not really matter for this question, as long as you suppose to have at least one "hole" in the $z-...
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2answers
42 views

An ohmic contact

It is claimed that Schottky type of contact between low work function p-type semiconductor and higher work function metal creates an ohmic contact in which current can flow both sides almost fluently ...
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2answers
29 views

Why Does a Bulb’s Individual Resistance Increase When Wired in Parallel?

When I wire three bulbs in a series, the resistance of each bulb is around three ohms (using R=V/I). If I rewire the same bulbs into a parallel circuit, the resistance of each bulb is slightly over ...
1
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1answer
36 views

How to (hypothetically) calculate $\tau$, the mean free time?

Referring to the Drude Model, I've seen a lot of excellent questions on whether $\tau$ should be thought of as the "average time between collisions" or the "average time until the next collision", and ...
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0answers
99 views

How to calculate the total resistance of a grid? [closed]

I am trying to calculate the total resistance of a metallic grid between the points $y=0$ and $y=L$ where the black lines represent metal and white areas are insulators. This is how I would proceed: ...
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3answers
88 views

Why is resistivity of conductor inversely proportional to the area of the conductor?

A simple Physics question regarding Ohm's law. The resistivity of the conductor is inversely proportional to the area of the conductor. I would like to have a simple explanation for this. How does ...
1
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1answer
60 views

Different batteries in a parallel circuit

I have come across this question in my physics textbook. Two batteries are connected in parallel to a resistor (see the above image). The first battery generates $U1 = 9V$ of voltage and its internal ...
1
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1answer
46 views

Does the supersonic aircraft feels less air resistance than when it flies with velocity less than sound

When ever I see pictures like this of some object flying at speed greater than sound , I see triangular waves . So I got question in my mind that Do supersonic objects weather its bullet or aircraft ...
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0answers
42 views

Why can’t we use the other formula for heat in this?

Two conducting wires of the same material and of equal lengths and equal diameter are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat ...
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4answers
80 views

What remains the same: voltage, current or resistance? [closed]

A current 1 ampere passed through a conductor which resistance is 10 ohms, if the current become 2 amperes, then will the resistance of the conductor will remain 10 ohms, and if not, then what is the ...
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0answers
28 views

Resistance of Square + Diagonal [duplicate]

How do you find the equivalent resistance from the top right corner to the bottom left corner, assuming all resistances are different?
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2answers
29 views

Potential in open branch of a parallel circuit with grounding [closed]

If the switch is still open, what will the electric potential at Q be, i.e. negative, positive or zero? Is there a potential difference across the grounded point and point Q, or R3, even though the ...
1
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3answers
76 views

RC circuit discharge while being connected to a battery?

I am facing a conceptual problem in analyzing the following situation which was part of a physics exam; A series RC circuit with $R = 200k \Omega$ and $C = 10 \mu F$ is connected to a 5V battery and ...
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8answers
1k views

Does Ohm's law $V = IR$ mean voltage causes current, or does it just say that voltage and current are related?

I have read that Ohm's law, $V=IR ,$ just means that $V$ is equivalent to $IR ,$ not that voltage is the cause of current. This is similar to the interpretation of Newton's second law, $\mathbf{F} = ...
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5answers
104 views

Does V=IR define resistance for any conductor? [closed]

Just wanted to confirm if the statement is always true or not
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0answers
14 views

Can I consider electron scattering with grain boundaries in metal as a tunneling process?

I am reading about the Mayadas-Shatzkes model (MS model). when electrons are scattered with the grain boundary, there is a probability that it will be transmitted to the other side of the grain ...
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0answers
41 views

What's the reason for this symmetry argument? [migrated]

Okay so I've learnt about various methods to find equivalent resistance in circuit. But there's one particular argument which I don't understand and I would be grateful if someone will prove it using ...
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1answer
26 views

Why is contact resistance measured in $\Omega~\mu m$?

In many papers the contact resistance of a metal in contact with a semiconductor is given in units of $\Omega~\mu m$, for example in the paper by Li et al. (Appl. Phys. Lett. 102 (2013), p. 183110): ...
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2answers
72 views

Energy dissipated across a resistor when charging a capacitor

I am a beginner in Physics and I am a little confused about RC circuits. I am working on a project in which I am measuring the power loss from a resistor when charging a capacitor in an R-C circuit. ...
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3answers
64 views

Can anyone tell me why the answer to this question is D? [closed]

I think the current will go through earth wire but my physics teacher told us the current will continue to flow through the circuit.
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2answers
36 views

Adding a capacitor in parallel improves power factor of an inductive circuit?

I know that to reduce power loss during transmission, we require a power factor as close to one as possible. This can be done by making $Z$ tend to $R$ which can be done by increasing $X_c$ such that ...
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2answers
34 views

Potential drop in slide wire (Potentiometer Experiment)

While doing the potentiometer experiment I was taught that the galvanometer will show opposite deflection on opposite ends of the slide wire. My questions are as follows: Why does this happen? In ...
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1answer
41 views

How does a load/resistor affects a Transformer?

If a resistor is connected on the secondary let's say 2 Ohms, this would have an overall effect on the primary & secondary circuit of a Transformer. It is obvious that the resistor would affect ...
3
votes
1answer
30 views

Which types of collisions contribute to electrical resistivity?

Do electrons only bump with other electrons in a circuit and that only causes resistance? Or do they bump with the nucleus as well? Here's a post I have been studying recently: The path of a ...
1
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4answers
68 views

Why isn't there any current in the Primary if Secondary circuit is opened in a Transformer?

Assume an ideal transformer, with no load/resistor attached on the Secondary (Open Circuit), it is said that the Primary would act as if it is an open circuit too, thus no current flows through the ...
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2answers
53 views

Why did a 12V battery affect my motor more than two 9v batteries in series?

In class, we made a coil of wire and used it to make a simple electric motor with a magnet. I put two square 9v batteries in series for a total of 18v to power the motor. I then used a larger 12v ...
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1answer
22 views

Nillsons Electrical Circuits Confusion

I'm reading this book Nilssons electrical circuits and I'm beginning to get frustrated/confused on some of the circuit diagrams. For instance this simple circuit with resistors in series. I understand ...
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1answer
33 views

How to calculate acoustic impedance of a megaphone

I'm working on a physics problem that asks how a passive megaphone (simple cone shape) can optimise the transfer of the human voice, compared to not using one at all. I understand that some of this is ...
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2answers
46 views

The importance and the role of a switch in an electrical circuit

There is this simple test: Three identical bulbs are connected in the circuit illustrated in the figure. When switch $S$ is closed: a] The brightness of $A$ and $B$ remains the same, while $C$ goes ...
4
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4answers
665 views

How does resistance convert voltage to current? [closed]

This is a statement that I read mainly on books about electronics. Could someone explain why after the resistance current is what makes things work and not voltage? Example from the Art of ...
0
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1answer
52 views

Is internal resistance of cell part of the equivalent resistance of the network of resistors?

Do we include the internal resistance of cell while calculating equivalent resistance of network? Take, for instance, the question given. Do we include the 1 ohm internal resistance while calculating ...
3
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4answers
41 views

Find relationships between the voltage difference across capacitor and resistor

I'm trying to learn kirchhoff's law. but im stuck on how to solve for a circuit that has both a resistor and a capacitor. How would you proceed?
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2answers
36 views

For a real battery, why is two identical bulbs in parrallel slightly more dim than just one in series

Image for reference: $$\begin{align} &r = 0.8\,\Omega\\ &\mathscr{E} = 1.5\,\mathrm V\\ &A = B = 6\,\Omega. \end{align}$$ The current when the switch is open, the only other resistor is ...
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2answers
60 views

Why in a DC series Circuit do bulb attached in parallel to highest resistance glow brightest? [closed]

I was performing an experiment in which there were five resistances connected in series and then I connected a bulb with each of the resistance. Each bulb was connected in parallel to each resistance ...
0
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1answer
47 views

LC-circuit and the current

A capacitor and a coil are charged in the LC circuit. When the circuit switch is closed, the current starts to flow. In theory the oscillations and the current do not deteriorate, but why in reality ...
2
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1answer
56 views

Resistor Capacitor circuits

I am a high school physics teacher and came across some issues today that I am unable to explain. We made a circuit with an $11$ V power source connected to a $100~k\Omega$ resistor and $100~\mu F$ ...
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1answer
24 views

Why do we subtract the voltage of the resistor from the emf voltage to find the terminal voltage?

I attached an image of a question from homework. I calculated the current in step 1) and then I calculated the voltage of the resistor. But why do I need to subtract that voltage from the emf voltage ...
0
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1answer
42 views

What do $I_{x2}$ and $I_{x3}$ represent in this Circuit? [closed]

I thought it would be Ix2 = I2 or Ix2 = 2I2. if that makes sense. The question asks for Voltage across R2 but i dont want an answer, i just need to know what those two symbols stand for so i can get ...
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1answer
26 views

Resolve The Envelope Detector Circuit

I was working on a little project and I was wondering if the envelope detector circuit could be resolved analytically. Let me explain. The circuit is the one shown above, I know the values of $C$, $R$...
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2answers
51 views

'Why don't electrons accelerate in a circuit' Confusion

https://physics.stackexchange.com/a/18806 Apparently he said 'at the same time', so when the electrons are 'pushed' by the electric field it is 'blocked' by the resistance simultaneously, if he said ...
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0answers
18 views

Difference in Electric conductivity based on connection type?

Is there a difference in electrical conductivity dipending on the way the Material is connected? For example, is there a difference between a copper wire connected to another one „via soldering“, ...
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2answers
33 views

Voltage when lamp burns out [closed]

In the question below, shouldn't the voltmeter read zero V because the circuit is broken and there is no current flowing? (the answer in the text is 12v)
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3answers
73 views

Why doesn't the flow electrons occur in a broken circuit?

Take a battery and connect a small led bulb across it with the help of two wires. The bulb will glow, but if I cut a small piece of wire from any part of the connecting wires,the circuit will not work ...