# Tag Info

## Hot answers tagged electricity

Accepted

### Would a grounded copper heat sink located near a room's ceiling be an effective way to reduce a room's temperature?

No. I like the beautiful simplicity of the idea, but gut instinct immediately complains that you maybe cannot get enough heat through a thin wire. In what sounds like a great exercise for students ...
• 781
Accepted

### Is Farady's law valid for conducting loop only?

Faraday's law is for a mathematical loop, even with nothing there.
• 1,104
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### Can we make electron drift velocity faster than light by reducing area of resistor?

A metal would melt before the drift velocity reaches anywhere near the speed of light (besides all the other mechanisms preventing the drift velocity from getting that high). In semiconductors, and ...
• 7,257

### Is the speed of signal transport via electricity as fast as light?

The propagation rate of a electrical signal along a wire depends on how much capacitance and inductance it exhibits on a per-foot basis. These parameters vary according to the diameter of the wire, ...
• 72.8k
Accepted

### Why do we use wires/conductors to transport energy?

Dielectrics are lossy too. And wires are good enough already. Indeed, it is possible to transport energy via dielectric, e.g. using light in optical fibers. But there is still some energy loss due to ...
• 27.8k

### Why can't electric field by a single charge be at an angle?

Op has been getting several answers which may be correct but appear to be above the level of what OP was looking for. So I am taking a simpler approach. Consider the following diagram where we observe ...
• 2,175

### Why can't electric field by a single charge be at an angle?

At an angle to what? If you are imagining a point charge, it’s a coordinate singularity. If you stand at the North Pole, every direction is “south.” If you have an object which really has zero size,...
• 70.2k

### Which type of star is most effective for solar power?

If you are using photovoltaic cells then all you care about is the flux of energy above the band gap in your photovoltaic devices. Even for sunlight, about 50% falls below this (wavelengths above ...
• 111k
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### EM energy flux and heat distribution in a cylindrical conductor

For DC current, the current density $\vec J$ and the electric field $\vec E$ are both more or less uniform in the conductor. This means the Joule heating power density $\vec J \cdot \vec E$ is also ...
• 7,257
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### What is the signal velocity in a very thin enameled magnet wire?

In theory, for a straight wire in empty space, the TEM mode centered on the wire has only finite energy in the insulation, but infinite energy outside. The insulation thus has no effect on the wave ...
• 3,269

### Why does electrolytic conductance increase with dilution?

Conductivity is a measure how fast charges can travel in medium, i.e. $$\sigma = -q \mu$$ where charge mobility is defined as : $$\mu ={\frac {q\ell }{m^{*}v_{_{\rm {F}}}}},$$ where $v_{_F}$ is ...
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Accepted

### Using the sky and ground as a battery

You'd need a very big electrode, and you'd need extreme power conversion. The voltage is typically 100 kV per km altitude, but only 2 pA current per square meter. Way too much voltage, and way, way ...
• 3,269
1 vote

### Does passing an electric current along a strip of metal submerged in saltwater cause anything?

Yes. Pumping current into the hull of a ship in moored storage has been used for decades to prevent the hull from corroding in constant contact with sea water. To accomplish this, a very large carbon ...
• 72.8k
1 vote

### Why is current density in a conductor of uniform cross sectional area constant at all points?

"Are there any fluctuations at all in reality?" In reality, there is Johnson-Nyquist noise: thermal current/voltage fluctuations in the conductor. This is routinely measurable with sensitive ...
• 3,269
1 vote
Accepted

### Why is current density in a conductor of uniform cross sectional area constant at all points?

A uniform current density $\vec{J}$ is just as much an abstraction as a uniform charge density $\rho$. Even if a "real" charge density $\rho$ is made up of a bunch of different point charges ...
• 37.2k
1 vote
Accepted

### Is electric potential inversely proportional to the voltage at a point?

However, Electric potential is the amount of energy needed to bring a charge/particle from earth to that point. The Wikipedia article states that the electrical potential is "the amount of work ...
• 55.6k
1 vote

### Is electric potential inversely proportional to the voltage at a point?

Electrical potential (like other potentials) is only defined to an arbitrary additive constant. You seem to be trying to compare potentials defined with different constants and getting confused. ...
• 22.8k
1 vote

### EM energy flux and heat distribution in a cylindrical conductor

Let’s choose a cylindrical coordinate system $\rho,\theta,z$ along the axis of the wire. We’ll assume that the wire is the the positive conductor in some electric circuit, and therefore has a small ...
• 70.2k
1 vote

### Is it possible to convert static electricity into current electricity?

One can produce static electricity continuously for example by a Van de Graaff accelerator (Look it up in wikipedia) it is used to create a current of fast electrons or other elementary particles ...
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1 vote

### Which type of star is most effective for solar power?

Only the luminosity of star and the distance to it go into your problem (the power collected would be proportional to the luminosity and inversely proportional to the square of the distance). If you ...
• 1,529
1 vote

### Why can't electric field by a single charge be at an angle?

The symmetries of the charge distribution say something about the symmetries of the resulting electric field. For example $\rho$ has rotational symmetry $\implies$ $\vec E$ only depends on $r$ $\rho$ ...
1 vote

### Does an X-Ray tube have an electric field inside of it?

An external high voltage source is connected across the anode and cathode; this voltage creates an electric field inside the tube that accelerates the electrons onto the target. The voltage is ...
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1 vote

### Why can't electric field by a single charge be at an angle?

The experimental study of electricity led to modeling the data with formulas that not only modeled the data, but were also predictive of new measurements. The attraction between two point charges . ...
• 221k
1 vote

### Is Farady's law valid for conducting loop only?

You can apply Faradays law for any loop as long as it is complete
1 vote
Accepted

### What's the electric field inside a capacitor with AC current?

To the best of my knowledge that'd mean $U_C = U_0 \,\sin(\omega t) = E\,d$ what'd be outrageous, because the field ain't homogeneous. Electric field inside capacitor is still homogeneous even if ...
• 27.8k
1 vote

### What's the electric field inside a capacitor with AC current?

You can set up a force equilibrium with the drag force and gravitational force in between a capacitor with an electric force too and with the DC case it's the Millikan's oil-drop experiment. I found ...
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Only top scored, non community-wiki answers of a minimum length are eligible