# Tagged Questions

Electrostatics is concerned with the electrical fields and scalar potentials of stationary electrical charges and charge distributions. Use this for questions about electromagnetic situations in which currents and magnetic fields are absent, otherwise use [tag:electromagnetism] and/or [tag:magnetic-...

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### Direction of motion of particle when placed on line of force

An electric line of force in the $x-y$ plane is given by equation $x^2+y^2=1$. A particle with unit positive charge, initially at rest at the point x=1,y=0 will move along the circular line of force. ...
1answer
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### Four equally charged electrons are placed at the corners of a square. What charge should be placed in the center to keep them in place? [closed]

Here is a drawing: http://imgur.com/VdW1Xmv Trying to solve this question. I understand that the charge in the center needs to be positive, and the sum of all forces should be 0. But how do I ...
1answer
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### Nonuniform charge distribution: total charge? [closed]

Can someone explain how the answer to part A is zero? All of my attempts at the question result in a non-zero answer.
1answer
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### Electric field integration? [closed]

If we have a rod uniformly charged with $Q$ stretching from $-a$ to $a$ on the $x$-axis as shown in the picture And we want to calculate electric field in point $2a$ on the $x$-axis, we know that ...
1answer
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### Electricity problem [closed]

• Two small metallic spheres, each of mass 5 g, are suspended as pendulums by light strings from a common point as shown in Figure. The spheres are given the same electric charge, and it is found ...
3answers
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### Definition of equivalent capacitance

I know that equivalent capacitance of multiple capacitors in series is $$C = \left(\frac{1}{C_1} + \cdots + \frac{1}{C_n}\right)^{-1}$$ and in parallel is $$C = C_1 + \cdots + C_n.$$ But there are ...
2answers
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### Do I need to use Pythagorean Theorem in 3d space for determining electric field induced by an infinite line of charge on a point?

An infinite line of charge with linear density λ1 = 8.4 μC/m is positioned along the axis of a thick insulating shell of inner radius a = 2.3 cm and outer radius b = 4.9 cm. The insulating shell ...
3answers
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### How is Capacitance affected by a seperation distance and with or without a battery?

The questions specifically says this : A parallel-plate capacitor initially has capacitance $C$. The distance between the plates is then doubled, with a $9.0V$ battery connected. The battery is then ...
1answer
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### Switching off Magnetic Field [closed]

A line charge (charge per unit length 'k') is put onto rim of wheel of radius 'R' which is then suspended horizontally, so that its free to rotate (spokes are made of non conducting material). In the ...
4answers
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### Distance can be zero

Can a distance between two particles can be exactly zero? Example: If I have two opposite charged particles having uniform charge. They will attract each other and the distance between them will ...
2answers
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### The separation between the two plates of a capacitor is increased

I had the following question on a quiz recently: A capacitor consisting of two parallel plates, separated by a distance $d$, is connected to a battery of EMF ε. What happens if the separation is ...
3answers
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### $F\cos\theta$ is not proportional to $d\cos\theta$?

If I’m working in two dimensions and I wanted to calculate the net electrostatic force on charge C, where charges A and B are stationary, of the same charge, and placed on the y-axis equidistant ...
2answers
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### Proving charge on outer surface of parallel plate capacitor must be zero

If we have two conducting plates, with charge $Q$ and $-Q$, why is the charge on the outer surfaces of each conductor zero? I've been trying to wrap my head around the problem. Firstly, don't excess ...
0answers
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1answer
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### Electrical work and Coulomb's law

In some text books I've encountered the calculation of electrical work done on a point charge moving in an electric field (e.g. when demonstrating that electric force is conservative) is done by ...
1answer
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### Electrostatics: Cylinder and conducting plane question (method of images)

I was looking at some problems/questions about electrostatics and came across this question: An infinitely long cylinder of radius $a$ and with charge density per unit length $\lambda$ is placed ...
2answers
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### What is the meaning that electric charges flow from high to low potential till both acquire same potential?

I was reading about electric current and circuits. I read in my book that electric current is caused when charges flow from high potential to low potential till they both acquire same potential. So my ...
2answers
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### Some confusions regarding electrostatic shielding

A spherical conductor A contains two spherical cavities as shown. The total charge on conductor itself is zero. However, there is a point charge q1 at the centre of one cavity and q2 at the centre of ...
1answer
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### $\mathbf{J}$ and $\mathbf{E}$ having the same direction [closed]

Ohm's Law States that $\mathbf{J} = σ\mathbf{E}$ this implies then that $\mathbf{J}$ and $\mathbf{E}$ have the same direction . But we know that $\mathbf{E}$ in normal to a conductor and $\mathbf{J}$ ...