Questions tagged [electrical-resistance]
The tag applies to electrical resistance and resistors. DO NOT USE THIS TAG for non-electrical resistance.
0
votes
3answers
29 views
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-...
-4
votes
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 ...
0
votes
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 ...
0
votes
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 ...
-1
votes
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 ...
0
votes
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?
1
vote
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?
2
votes
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-...
1
vote
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 ...
0
votes
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
vote
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 ...
0
votes
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:
...
0
votes
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
vote
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
vote
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 ...
-1
votes
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 ...
-1
votes
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 ...
-4
votes
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?
1
vote
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
vote
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 ...
10
votes
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} = ...
0
votes
5answers
104 views
Does V=IR define resistance for any conductor? [closed]
Just wanted to confirm if the statement is always true or not
0
votes
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 ...
0
votes
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 ...
0
votes
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):
...
0
votes
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.
...
-2
votes
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.
0
votes
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 ...
0
votes
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 ...
0
votes
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
vote
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 ...
1
vote
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 ...
1
vote
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 ...
1
vote
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 ...
0
votes
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
votes
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
votes
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
votes
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?
2
votes
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 ...
-1
votes
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
votes
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
votes
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 $100~\mu F$ ...
1
vote
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
votes
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 ...
1
vote
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 $C$, $R$...
0
votes
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 ...
0
votes
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“, ...
1
vote
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)
0
votes
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 ...
