# Tag Info

### Why does charge distribute itself uniformly only on the surface of spherical conductors?

The below addresses the word "uniformly distributed over the surface" Solving the Laplacian equation may help. The spherical conductor is equipotential at the surface, say $V_{0}$ Set the ...

### Faraday's Law - When do we know when it is a motional EMF or an induced electric field?

My question is, how can we differentiate these 2 completely different scenarios from each other? Or are they the same scenarios? They are different descriptions of the same phenomenon, because they ...
• 35.6k

### Can dielectric slab be used to move an object?

In a real system, there will be other forces: things won't just float in space. The electrostatic force on the dielectric slab is purely attractive, in the direction pulling the slab into the ...
• 18.9k
1 vote
Accepted

### Infinite electrostatic plate acceleration

On way to do this is make your not-so-infinite plate a charge distribution on a disc (aligned on $z$ for reasons): $$\rho(r, \theta, \phi) = \sigma (1-\Theta(r-R))\delta(\theta-\frac{\pi} 4)$$ Now you ...
• 31.5k
1 vote

### For electric field between two parallel plate capacitor given by $Q/A*\epsilon_0$, how does the inverse proportionality of area make sense?

The formula that you've quoted applies to a capacitor for which the plates' dimensions are much greater than their separation. The result follows almost immediately from Gauss's law and symmetry, ...
• 34.9k

### For electric field between two parallel plate capacitor given by $Q/A*\epsilon_0$, how does the inverse proportionality of area make sense?

With increasing the area, the capacitance would increase, which you see from $C = \epsilon \frac{A}{d}$. The question now is whether you apply a voltage that is then constant or if you have a fixed ...
• 377

### Why decreasing the distance between a parallel plate capacitor increases the electric field? Wouldn't it remain the same? $\sigma/\epsilon_0$?

The capacitance has nothing to do with electric field, it is constant for a given capacitor. Learn more here https://www.physicskey.com/63/capacitance Electric field is proportional to charge and also ...
• 99

• 9,613

### Intuitive charge distribution

Starting from the inner positively charged point charge (assuming point charge for simplicity) and charge neutral but polarized outer shell, when you add negative charge to the outer shell, (0) the ...
• 504
1 vote
Accepted

### Intuitive charge distribution

"lets say I now add more negative charge to q1 while its in the 2nd state, does the negative charge migrate to the inside surface or remain at the outer surface." It remains on the outer ...
• 34.9k
Accepted

### In depth answer: Why do I see sparks when I remove synthetic clothes off my body?

The description in your main paragraph is correct. The phenomenon is the triboelectric effect. Dry skin (and dry hair) has an affinity for positive charge, while synthetic fabrics (and plastic) have ...
• 12.7k
Accepted

### Is Faraday's cage described in electrostatic 100% insulated?

Electrostatics problems do not consider cases where charges are moving. They are valid problems, but more complex. So you have one electrostatic problem. You add a charge and wait again for ...
• 36.4k
1 vote
Accepted

### Potential - metal sphere in a uniform electric field

Yes, but your last equation is valid for all $\theta$. You can use this fact and the orthogonality of the Legendre polynomials to conclude that all the coefficients are zero. Indeed, for “any” ...
• 9,613
1 vote
Accepted

### In an electrostatic field with zero divergence everywhere, where is the charge located?

You can look at the required charge when your field is given by your formula in a finite domain $D$ and zero outside. Physically, this gives you a surface charge on the boundary $\partial D$ given by: ...
• 9,613

• 534
1 vote

### Using method of images on ungrounded spheres

In 3D, the electric potential converges to a finite value at infinity (provided the charge distribution is sufficiently localised). Grounding a conductor means that its potential is set to be equal to ...
• 9,613

### Parallel plate capacitor infinite energy

A system's energy, which is conserved when the system is closed, is the sum of the kinetic and potential energy. You've forgot to take the potential energy, namely $\Delta x Eq$, into account.
• 215
Accepted

### Electric field produced by a uniformly polarized sphere

The macroscopic Gauss's Law for $\vec{D}$ is not enough to solve this problem. In a (static) system with the divergence equation $\vec{\nabla}\cdot\vec{E}=0$, you can conclude that $\vec{E}$ is a ...
• 15.6k
1 vote

### Electric field produced by a uniformly polarized sphere

You don't need to specify the $z$ direction. To get a uniform polarization in a linear dielectric, you need to immerse it in a uniform external field, $E$, where $E$ is the value far from the field. ...
• 31.5k

### Parallel plate capacitor infinite energy

Let's say the capacitor has voltage $V$ and charge $Q = CV$. Let's assume that a positive charge $+q$ and a negative charge $-q$ are created halfway between the plates, with $q\ll Q$ (and equal mass, ...
• 11.9k