Physics Stack Exchange
Physics Stack Exchange

Questions tagged [electric-fields]

For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than the [electricity] tag, as questions about the phenomenon & theory of electricity do not necessarily involve the discussion of fields.

For questions that utilize the concept of electric fields (commonly denoted by the letter E), or for questions whose answers likely involve electric fields. More specific than , as questions about the phenomenon & theory of electricity do not necessarily involve the discussion of fields.

4736 questions
58
votes
7 answers

In electrostatics, why the electric field inside a conductor is zero?

In electromagnetism books, such as Griffiths or the like, when they talk about the properties of conductors in case of electrostatics they say that the electric field inside a conductor is zero. I have 2 questions: We know that conductors…
Revo
  • 17,504
49
votes
6 answers

Can someone please explain magnetic vs electric fields?

I've looked through about 20 different explanations, from the most basic to the most complex, and yet I still don't understand this basic concept. Perhaps someone can help me. I don't understand the difference between the electric and magnetic force…
user1299028
  • 939
49
votes
6 answers

Why is electric field strong at sharp edges?

I learned about the coronal discharge, and the common explanation is because the electric field is strong where radius of curvature is small. But I haven't found anything yet that explains why electrons like to crowd at the peaks, and escape from…
Calmarius
  • 8,428
48
votes
8 answers

How is it possible to accelerate a neutron?

It is possible to accelerate a charged particle in an electric field, how is it possible to accelerate a neutron? How can we control its velocity?
Clandestino
  • 621
  • 1
  • 7
  • 8
45
votes
5 answers

Difference between electric field $\mathbf E$ and electric displacement field $\mathbf D$

$$\mathbf D = \varepsilon \mathbf E$$ I don't understand the difference between $\mathbf D$ and $\mathbf E$. When I have a plate capacitor, a different medium inside will change $\mathbf D$, right? $\mathbf E$ is only dependent from the charges…
kame
  • 949
39
votes
6 answers

Why does the density of electric field lines make sense, if there is a field line through every point?

When we're dealing with problems in electrostatics (especially when we use Gauss' law) we often refer to the density of electric field lines, which is inversely proportional to the radius in the case of a single point charge (all field lines are…
odg
  • 481
39
votes
1 answer

Can lightning be used to solve NP-complete problems?

I'm a MS/BS computer science guy who is wondering about why lightning can't (or can?) be used to solve NP complete problems efficiently, but I don't understand the physics behind lightning, so I'm posting here. What seems peculiar to me about…
micahhoover
  • 525
35
votes
5 answers

What are the fields produced around a current carrying conductor?

If you consider a current carrying conductor, every instant an electron enters the conductor, another electron will be leaving the conductor. Thus, the current carrying conductor will not be charged (i.e. it would not have any net positive or…
Sensebe
  • 5,889
34
votes
10 answers

How is energy "stored in an electric field"?

My physics teacher told me the statement "The energy of a capacitor is stored in its electric field". Now this confuses me a bit. I understand the energy of a capacitor as a result of the work done in charging it, doing work against the fields…
anon
  • 522
33
votes
4 answers

How does energy flow in a circuit? Which is correct?

I have been very interested in this question since reading Electricity Misconceptions by K-6 There are two perspectives I have come across for how energy flows in a circuit: Electrons carry charge. As the charges move, they create an…
PhysicsMathsLove
  • 1,104
33
votes
3 answers

Why is there no gravitational magnetic field? (Or, is there?)

We can think that the electric field and the gravitational field operate similarly in the sense that the forms of their governing laws (namely, Coulomb's law and Newton's law respectively) are strikingly similar. The only difference one can point…
user87745
32
votes
5 answers

Are Maxwell's laws mathematically precise?

Electrodynamics makes heavy use of vector calculus, which in turn is about differentiation and integration of scalar and vector fields in $\mathbb{R}^3$. At this point everything seems fine to me, since the physical space is isomorphic to…
1__
  • 1,644
31
votes
3 answers

Detection of the Electric Charge of a Black Hole: How can an electromagnetic field escape the event horizon of a Reissner-Nordström black hole?

By the "No Hair Theorem", three quantities "define" a black hole; Mass, Angular Momentum, and Charge. The first is easy enough to determine, look at the gravitational effects, and you can use the Schwarzschild formula to compute the mass. Angular…
Benjamin Horowitz
  • 4,316
30
votes
9 answers

Paradox with Gauss' law when space is uniformly charged everywhere

Consider that space is uniformly charged everywhere, i.e., filled with a uniform charge distribution, $\rho$, everywhere. By symmetry, the electric field is zero everywhere. (If I take any point in space and try to find the electric field at this…
Revo
  • 17,504
29
votes
5 answers

Why is there an electric field in a wire even though it is a conductor?

If you take a perfect conductor, there cannot be a field across it since if there were, the particles would arrange themselves in a way to cancel out the field right? Yet, why does the same not hold true for a wire. A wire is essentially a long,…
1110101001
  • 1,625
1
2 3
…
99 100