All Questions
29
questions
5
votes
1
answer
3k
views
Can conductor be charged?
I have a copper conductor. For a while, I apply a voltage of $12kV$ DC from a source. After removing the source, will the conductor stay charged from the source if is not earthed? Will it discharge ...
- 185
5
votes
2
answers
503
views
How does current flow in a irregularly shaped heterogeneous resistor?
The motivation for my question is understanding how electricity gets through your skin as opposed to running along it, and how the presence of things like water on the skin affect the relative ...
user24082
4
votes
1
answer
223
views
At what distance is lightning dangerous for someone lying down?
My 8 yo child told me that they learned at school that they should lay down flat on the ground in case of lightning. I told him that the more correct position is crouching down with feet together, but ...
- 516
3
votes
1
answer
5k
views
What is the difference between electric spark and electric arc?
In my student book they separate these two and indicate that sparks need high voltage to occur while arcs need low voltage with normal or low pressure and electric arcs CAN come with heat and bright ...
- 59
2
votes
2
answers
422
views
Fundamentality of voltage to current
From Ohm's Law :
Ohm's law states that the current through a conductor between two points is directly proportional to the potential difference across the two points.
I would like to know if ...
- 950
2
votes
4
answers
1k
views
Why is current density in a conductor of uniform cross sectional area constant at all points?
According to what I was taught, if current was dispersed “uniformly,” current density would remain constant.
So, in a conductor, the 'current density should be the same at all points.' But, given that ...
- 444
2
votes
3
answers
146
views
Flow of charges
I saw this question which asks for the condition for flow of electricity through the conductor i know that electricity will flow only when there is a potential difference achieved between the ...
- 1,200
2
votes
1
answer
1k
views
Can electric potential be discontinuous?
I am studying the following problem, which is 9.11 of "Modern Electrodynamics" by Zangwill.
The idea is that you have a wire attached to a perfectly conducting sphere (radius $a$) buried into the ...
- 1,544
2
votes
1
answer
2k
views
Why should a battery not give current in order to measure EMF?
Emf is the "potential difference (PD) across the terminals of a battery when it is giving no current to the circuit."
What does "when it is giving no current mean"? Will the PD across the terminals ...
- 1,159
1
vote
5
answers
2k
views
Field inside a wire?
This answer gives a great explanation of why the field inside a wire connected to a battery must be equal at all points: Why doesn't the electric field inside a wire in a circuit fall off with ...
user41086
1
vote
1
answer
11k
views
Current against the inverse of resistance graph, $I = V/R +c$
If I have a plot of current ($y$ axis) against 1/Resistance ($x$ axis).
The circuit it is measured from is a simply 2 resistors connected in parallel to battery, where the potential across the ...
- 6,927
1
vote
1
answer
113
views
Derivation and theory for $I = kV^n$ [closed]
I performed an experiment in college to study the nature of a filament of a lamp, determine $k$ and $n$ in the relation mentioned, and study the variation of wattage of a lamp. I assume ohm's law is ...
- 33
1
vote
1
answer
1k
views
How is PD = EMF for an open circuit?
For an open circuit, $V = E - Ir$. People say since there is no current flowing, $V$ is equal to $E$. However $V = IR$, where $R$ is the external resistance, that doesn't exist either so how can ...
1
vote
1
answer
108
views
What is the point of using an inverting amplifier in a circuit? [closed]
This may be a simple question to most of you, but I'm having trouble understanding the concept behind the use of an inverting amplifier.
What is the purpose of using an op amp in an inverting ...
- 113
1
vote
2
answers
1k
views
Two charged spheres connected by a wire
I have a few doubts about this problem. So we have two charged spheres of radius $r_1$ and $r_2$, one is initially charged with a charge $Q$, while the other one is initially without charge. The ...
