Electrostatics Definition and 663 Threads

Well,I think this is interesting.I invite people to think over it. consider a charged spherical shell.Throughout its interior,E=0. Now,consider the centre.From Laplace's equation and Earnshaw's theorem,this point is not a point of potential minimum.So,a charge at this point cannot be in stable...

Homework Statement A line charge has density λ and extends along the x-axis from -a to +a. Find the electric potential at a point r on the x-axis (r>a). Use your result to find the E-field at r.Homework Equations V = \frac{1}{4\pi \epsilon _0}\int\frac{dq}{r} The Attempt at a Solution I've said...

Can someone say why it is said that in electrostatics,the test charge may be moving very slowly?Specifically,what is wrong if the test charge moves at a speed which is a significant proper fraction of speed of light?

Homework Statement 3 balls are on a ?string?/line?. Each are equally displaced, 72cm. Ball A has a charge of -50e5c, Ball B a charge of +25e2, Ball C -10e10. 1. What is the net force applied on the middle ball (Ball B)? 2. Assuming a force to the right(ungiven name of Ball D?) (of Ball C)...

Homework Statement 2 small spheres each having a mass of 0.1g are suspended from the same point on silk threads 20cm long. When given equal charges, they repel, resting 24cm apart. Calculate charge of each. Homework Equations F(w)=mg(a) F=kQ(1)Q(2)/d^2 k=8.987x10^9 N*m^2 / c^2 The...

I have a problem in electrostatics in which there is a uniformly charges semi-sphere of radius a with its base in the xy-plane and I want to find the electricfiled at some point h on the z-axis. What I am having trouble with is that how do you specify the vector that goes from an infinitesimal...

From Griffiths, Third edition Intro Electrodynamics I've been working on this problem, and I get 2 different answers. I get the same answer for parts b and c, but not for a. I know I'm probably just doing something silly along the way, but I can't find my mistake... Homework Statement...

Homework Statement 1) From the observation that there's an electrostatic attraction between object A and B, what's the most you can conclude about the electric charge on A and B? 2) A plastic sphere with a positive charge of 4.8E-19 C is held stationary in a gravitational field of strength...

Homework Statement What is the radius of the orbit of an electron traveling at 9.0E6 m/s around a zinc nucleus(which contains 30 protons)? Homework Equations F=(kQq)/r^2 F=QE ac=v^2/r Fnet=ma The Attempt at a Solution 30 protons x 1.6E-19 = 4.8E-18 C electron - 1.6E-19 C F=ma...

Homework Statement how to use coulomb's law to find the r value of the three points when the total distance is 50 cm Homework Equations f=Kqq/r^2 The Attempt at a Solution i assumed that is it was uniform and sais r1+r2=r3 but now i think that is wrong

Homework Statement Calculate the magnitude of the field strength at point P as shown. The distance between the centers of the 1.5E-6 C and the 9.2E-6 C charges is 5.6 cm.. Homework Equations E = kq/r^2 E = F/Q E = V/d The Attempt at a Solution Used tan and sin of 50 to find all...

Hello, I am doing electrostatics at the moment and have difficulties to solve the following problem. Any hint that helps me to find the answer will be appreciated! "On every corner of a square are movable point charges with the charge of 'q'. Where does a fifth movable point charge have to...

Homework Statement An electron orbits a nucleus which carries a charge of +9.6E-19 C. If the electron's orbit radius is 2.0E-10 m, what is its electric potential energy? Homework Equations Ep = kQ1Q2/r V = kQ/r V = Ep/Q The Attempt at a Solution I tried using Ep = kQ1Q2/r Ep =...

1. The problem statement, all variables and 'given'/'known' data A proton accelerates from rest from plate X to plate Y. If the potential difference between the 2 plates is 60.0V, what is the speed of the proton when it reaches plate Y? 2. Governing equations V = E/q Ekf - 1/2mv^2The Attempt...

1' after a metal rod rubbing with a cloth, is the metal rod remains neutral in charge whereas the cloth will be positive charge? 2' a small pieces of paper and aluminium foil are attracted by charged metal rods when the rods are brought close to them. however, the former stick to the rod...

Do UAM equations apply on an atomic scale when dealing with protons and electrons etc?

Particles of charge Q1 = +62 µC, Q2 = +45 µC, and Q3 = -80 µC are placed in a line (Fig. 16-37). The center one is 0.35 m from each of the others. Calculate the net force on each charge due to the other two. I have found the forces between Q1 - Q2, Q2 - Q3, and Q1 - Q3. Here is my...

A uniform electric field has a magnitude of 3.0 103 N/C. In a vacuum, a proton begins with a speed of 2.4 104 m/s and moves in the direction of this field. Find the speed of the proton after it has moved a distance of 1.0 mm. I am confused with the fact that there is a velocity int his...

Hi. I'am having trouble with 2 of my homework problems. Usually I do pretty good in physics but electrostatics unit turned out to be very confusing for me. I think I figured out all the other homework questions but these 2. I drew those out myself but I think they are pretty understandable...

I know an argument that i don´t like. It say´s: If there were electric field inside a conductor in electrostaic equilibrium, it would exert force on the charges and move them. But this argument implies that there are infinite charges inside the conductor. This is not very plausible, if...

1)Two small equally charged spheres, each of mass m, are suspended from the same point by silk threads of length l.The distance between the spheres x<<l.Find the rate dq/dt with which the charge leaks off each sphere if their approach velocity varies as v=a/(x)^0.5, a is a constant...

Hi, I'm a bit stuck with some things in electrostatics. My first problem: in my textbook, when they try to derivate the formula for the potential of a point charge: V(b) = - \int E.d\mathbf{l} = -\frac{q}{4 \pi \varepsilon_0} \int_\infty^b \frac{1}{r^3} \mathbf{r}.d \mathbf{l} they...

A conicalsurface(an empty ice cream cone) carries a uniform surface charge density sigma.The height & radius of the cone are h & R.Find potential difference between apex & centre of the top

we take the potentisl of the Earth to be equal to zero for solving some problems though the potential of Earth is not equal to zero . why is that ? or when can we do that ?

Hi all, I have this problem in my physics homework, which is not trivial. This is not a graded homework fortunately but I would like to see the solution for it and learn. I have attached my attempt at solving this problem. Not sure if this is the right way to solve it, and so I would like...

We have a charge distribution in which all the charges are in equilibrium due to electrostatic forces . Can we prove that none of these charges will be in stable equilibrium ?

Magnetostatics -> Electrostatics?? I have a questions and I am afraid that I might look very dumb for asking such questions, so forgive me first. I heard many times how Maxwell's equations along with Lorents Force Law tells all the story of EM dynamics. So I wanted to see if I can show...

the formula v = kq1/r +kq2/r if a charge is -2 micro couloumbs for instance is that put into the equatoin and it becomes minused instead or the sign doesn't effect q in the formula cuase i remmeber in the f = kq1q2 the sign has no effect

Hey everyone, I'm not sure if this question warrants the "advanced physics" forums, but it would be nice if some of you smart people could give me a hand with this problem. Two 5g spheres are charged to +100nC and hung from 1m long strings. What is the angle produced due to the repusive...

Answers or Steps, or even formulas are welcome, Any answer to any of them! Okay First qusetion... A proton is placed in an electrical field that counters the effect of gravity at sea level. Find The Electric Field.Second Question... A Proton is accelerated from rest in an electric field of...

The problem says Verify by direct integration that F= qE = - q^2/(16*pi*epsilon_0*d^2) in the "x unit" direction is the resultant of the Coloumb force between q and the induced charge described by sigma_f(y,z) = -qd/(2*pi*(d^2+y^2+z^2)^3/2 ------------- Okay, I am not sure...

In "Classical Electrodynamics - 3rd Ed.," J.D. Jackson has an exercise, 1.10, to derive the mean value theorem of electrostatics. Does anyone know of a derivation which is located on the web? Pete

hi, this is a great forum here and i was wondering if anyone could lend a helping hand , it would be great. im currently studying at univercity for electronics engineering and have been given some physics questions to work onover the holidays. I ahve spend quite some time on this question...

Electrostatics problem Hello! The problem I'm trying to get help on is the following: You have an evenly charged circle with the total charge Q and radius R. There is also a point-charge q located a (thats a symbol, not an article) meters from the center of the circle (the point charge is...

I have a little doubt. why is there an inverse square law in electrostatics?why not some other than the inverse square? is there any relation/connection between the charges and the inverse square?

the below figure make small angles theta1 and theta2 with the vertical. Figure 21-50 (a) If Q1 = Q, Q2 = 3Q, and m1 = m2 = m, determine the ratio theta1 / theta2. (b) If Q1 = Q, Q2 = 2Q, and m1 = m, and m2 = 4m, determine the ratio of theta 1 / theta 2. I don't get the forces that are...

griffiths electrostatics problem if you have the text on you, I'm looking at question 2.46 (in the third edition). i am given V(\mathbf{r}) = A\exp (-\lambda r)/r i found that \mathbf{E} (\mathbf{r}) = A\exp (-\lambda r)(\lambda /r + 1/r^2) \hat{r} the solution for \rho...

I'm trying to calculate the electric force between two uniform line charges on a single axis; does anyone have any sample solutions?

Three point charges of +2μC, +3μC and +4μC are at the vertices of an equilateral triangle ABP, respectively, having sides of 10cm. What is the resulting force R acting on the +4μC charge? the hint in class is to use the law of cosines this is how i set it up force acting on 4uc from...

Just got out of my E&M class lecture about Coulombs Law, I'm having trouble getting off of the ground with an electrostatics question: Question: Three charged particles lie on the x-axis (fig. 1). Particles 1 and 2 are fixed. Particle 3 is free to move, but the electrostatic force on it...

Hello everyone! I've recently been messing around and experimenting with electrostatics and have some questions I can't find answers to. Ok here they are: 1. If I understand this correctly a neutral object is attracted to positive and negatively charged objects. If this is true, why does...

Hey all, I'm trying to calculate the charge that forms on two adjacent and asymetrical cylinders when a voltage is put between them. The figures I was using was something like 1mm radius for one and 10mm radius for the other, a voltage of about 20kV and a separation of a few cm. I thought...

here is a problem: if a dipole with charges +/- q is brought near a neutral metallic sheet then what is the electric field near the sheet?

Suppose you've got a metal sphere of radius R and it is surrounded by a metal spherical shell with inner radius r_a and outer radius r_b. The metal sphere has total charge Q. The first thing i had to calculate was what the induced surface charges are on the shell. That was pretty easy, but they...

Problem: A metal sphere of radius R carries a total charge Q. What is the force of repulsion between the "northern" hemisphere and the "southern" hemisphere? My book gives a formula for the electrostatic pressure: P = \frac{\sigma ^2}{2\epsilon _0} pushing the surface outwards (and...

Problem: Two spherical cavities, of radii a and b, are hollowed out from the interior of a (neutral) conducting sphere of radius R. At the center of each cavity a point charge is placed -- call these carges q_a and q_b. (a) Find the surface charges \sigma _a, \sigma _b, and \sigma _R. (b)...

1. A charged particle was accelerated from rest by a potential difference of 2.50 x 10^5 V. If the particle reached a maximum speed of 2.90 x 10^4 m/s, what potential difference would be required to accelerate this particle from rest to a velocity of 7.25 x 10^4 m/s? 2. The centers of two...

I am having trouble with this problem There is a sphere haveing nonuniform volume charge desnity p=ar where a is constant and r is radial distance from centre of sphere. Radius of sphere is R we have to find electric field at centre of sphere. Thanx

two small spheres, each with 0.120g, have equal charges placed on them. Each sphere is suspended from the same point by its own silk fibre which are 75.0cm long. The repulsive force between them keep their centres 10.0cm apart. What is the charge on each sphere?

I've got the following problem: 1) We've got a charge -Q at location at the origin and two charges of the same magnitude but opposite sign at (a,0,0) and (0,a,0). Determine the total force on the charge at the origin. 2) We've got the same charge -Q at the origin but now a charge of 2Q at...