All Questions
29
questions
1
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2
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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 ...
0
votes
2
answers
469
views
Direction of current flow in circuit with multiple cells
As the point $A$ is earthed we know that its potential is zero, same is true for point $B$. Due to the cell between $B$ and $C$ we can say that potential at $C$ is $-3V$. So the potential at point D ...
0
votes
1
answer
163
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If a light bulb is connected to different voltages, is there a single method to calculate the utilized power?
If a bulb is marked at 100W and 200V, we know that the bulb utilises a power of 100W when connected to a 200V potential difference. So, can we say that the bulb, when connected to twice the potential ...
2
votes
1
answer
1k
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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
1
vote
1
answer
1k
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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 ...
5
votes
1
answer
3k
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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
-4
votes
3
answers
182
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Doesn't any massive conductor look like "ground" to an AC supply?
I've been puzzling over this excellent answer to the perennial "Why don't I get shocked by a hot wire if I'm not grounded?" question. The orders of magnitude just don't seem right for two reasons:
...
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4
votes
1
answer
223
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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
0
votes
1
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175
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How do the electrons know the route? [duplicate]
I've learnt in classroom that the requirements for electrical current to flow in a circuit are as follows:
there must be a closed conducting path between negative and positive terminals
there must be ...
- 13k
1
vote
5
answers
2k
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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
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
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
2
votes
2
answers
422
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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
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