E-field Definition and 180 Threads

What is the realistic break down value for E field in air. Text books say its 3*10^6 V/m But there are many websites, which go down to 1*10^6 V/m. If there is a dielectric like FR4, then the break down increases V=ε E*d ?, where ε is the dielectric constant for FR4.

Homework Statement http://postimage.org/image/cky823nof/ Homework EquationsE=kq/r^2 The Attempt at a Solution I figured I would just find the electric field produced at point * by each individual charge and then add them. For example if I were to set E1 to be the top molecule the field...

Homework Statement What diameter should the nichrome wire in the figure be in order for the electric field strength to be the same in both wires? Homework Equations σ = 1/ρ J = σ*E...I/A = σ*E...I = σ*E*A Then, equate the current equations for each wire. The Attempt at a...

Homework Statement In my honours lab we are performing the Milikin drop experiment, and we've come into a slight problem, where when calculating the radius of the drops and the charge on the drops, the charge seems to vary with change in E-field. When performing the experiment we first...

Homework Statement There is a non-conducting charged rod with length L=.0815(m) and linear charge density λ=-5.9x10-14(C/m). The rod is placed parallel to and on the x-axis, and at a distance a=.12(m) from the right-most end of the rod is point P. Calculate the magnitude and direction of E...

Homework Statement A uniformly polarized dielectric disk surrounded by air is lying at a conducting plane, as shown in the figure. The polarization vector in the is, \vec{P} = P \hat{k}, the disk radius is a, and the thickness d. Calculate the electric field intensity vector along the...

Please refer to the image that is attached Homework Statement For each of these prisms and cubes (a-f), state whether the surface encloses a: -net positive charge -net negative charge or - a zero net charge Homework Equations The Attempt at a Solution The E-field is...

Homework Statement Charge 1 is 8nC and is located at x=-1m. Charge 2 is 12nC and is located at x=3m. Find x where e field is equal to 0 due to the 2 charges.Homework Equations e=kq/(r^2)The Attempt at a Solution The answer is x=1.8, but I just can't seem to get anywhere near that. I know that x...

Homework Statement What is the electric field within the rod? (See attached document for full question) Homework Equations emf = -d(phi)/dt= integral (E dot dl) The Attempt at a Solution The rod is moving within a uniform magnetic field. There is no change in flux through the...

Homework Statement A long insulating cylinder has radius R, length l, and a non-uniform charge density per volume \rho = e^{ar} where r is the distance from the axis of the cylinder. Find the electric field from the center of the axis for i) r < R ii) r > R The Attempt at a Solution...

Homework Statement A) Calculate the work performed by an external agent to move a charge of -0.59x10-12 C from `i' to `b'. B) Calculate the magnitude of the electric field at `k' Homework Equations W = q∆V Where ∆V is the potential difference between the two potential lines...

Homework Statement Two infinite-plane non-conducting, thin sheets of uniform surface charge p1 = 13.35 uC/m2 and p2 = -8.65 uC/m2) are parallel to each other and d = 0.245 m apart. (As shown in the diagram below.) What is the electric field between the sheets? (Note: the field is positive if...

9. [1pt] As shown in the figure above, a ball of mass 0.480 g and positive charge q =32.7microC is suspended on a string of negligible mass in a uniform electric field. We observe that the ball hangs at an angle of theta=15.0o from the vertical. What is the magnitude of the electric field...

Homework Statement Parallel plate capacitor with circular plates with radius of 26mm and a plate separation of 6mm. A sinusiodal potential difference is applied across the capacitors plates with Vmax = 170V at a frequency of 60Hz. 170sin(2*pi*60Hz*t) Homework Equations V = ∫E∙dl = El (l...

does anyone know why the forces point in such a direction? basically, its a dipole (y-orient) in an E-field but why do the forces on the +q and -q slant as such? thanks

Homework Statement http://img825.imageshack.us/img825/5992/gauss.th.png Uploaded with ImageShack.us 2. Solutions For b) - iv They say the E-field is 0 for r > c Why? Also for part c), they say the answer should be the integral from r = a to r = b. My question is, why...

I am having trouble with a homework problem assigned by my physics professor. An infinitely long cylinder of radius a and relative dielectric constant Er is immersed in a static electric field E=Eox where x is supposed to denote a unit vector in the x direction. The cylinder is alligned on the...

Homework Statement http://plato.stvincent.edu/physics/past/ph112/2008/exam1/s3.pdf How do we know the E-field is radially? And not through the top and bottom?

Homework Statement a) What is the E-field at the center of a metal ring which has uniform charge density? b) Is E=0 for any other point within the circumference of the ring?2. The attempt at a solution For (a), since the ring has uniform charge density and is symmetrical, based on symmetry...

pardon me for asking such silly question. Why is it that the E-field in the interior of a conducting solid zero? even when the conducting solid have excess positive (or negative) charges? and this conducting solid is placed in an external E-field, will the E-field in the conducting solid...

Hello, I need help solving an integral in the line charge equation for my electrodynamics class. I'm using Griffiths third edition and I understand where the components of the problem come from, but I can't seem to solve the integral, although I'm sure it's very basic. It's been awhile since I...

Homework Statement Plane X=0 has a uniform charge density, \rhos while plane X=a has -\rhos. Determine the electric field intensity in region X<0. Homework Equations E=\frac{Q}{4\Pi\epsilon0R2}aR The Attempt at a Solution I already know the answer to this question. What I'm...

I was trying to read up on the effects of the Lorentz transforms on electromagnetic fields in the stationary and moving frames and came across the following equation for the E-field: [1] E= \frac {Q}{4 \pi \epsilon_0 r^2}* \frac {1- \beta^2}{(1- \beta^2 sin^2 \theta) ^{3/2}} The first...

Hi, What is the equation for a E field of a single pulse of a laser? If that laser is shined onto say a grating spectroscope (square law detector), how can I go about deriving an expression for Intensity as a function of frequency at the output of the spectroscope? I know that the square...

Homework Statement Point charge q1= -5.00 is at the origin and point charge q2= +3.00 is on the -x axis at x= 3.00 cm. Point P is on the y-axis at y= 4.00 cm . Calculate the electric fields E1 and E2 at point P due to the charges q1 and q2. Express your results in terms of unit vectors...

I find it a bit hard to visualize E field and H field inside a waveguide, specially in modes other than TEM. I know E and H are perpendicular to each other and to the direction of propagation. But I need to see some examples or something like a right hand rule. Basically, I am confused.

Hi, I'm looking through my notes on em waves in dielectrics and the fresnel equations and I've been stuck on this for a while. It states that if the complex amplitude = E0eiΦ is positive there is no phase change. However when the value is negative, the phase change Φ is π.. Why is that...

In my electromagnetic engineering class we were talking about Hertzian dipole antennas with an oscillating current source (transmission line) driving the antenna. As part of the description of the behavior as the two ends of the antenna have opposite charges an electric field is created from...

ok, so I've got an arc between two electrodes. What is the direction of the electrical field if there is an electrical field?

Homework Statement Єr = 3.0, atomic density = 1028 atoms/m3. The mag. of the E-field is 10,000 [V/m]. Two electrons in outer orbital shell will distort with an applied E-field. If both both electrons follow some orbital path as a pair, find spacing between center of nucleus and average...

Homework Statement E-field at (2[m], 30⁰, 90⁰) is E = 4aѳ [V/m]. Find the magnitude and direction of the dipole moment p. Homework Equations I know that I need I need to solve for the equation: p = Qd, where Q is the point charge at the given point and the distance between +Q and -Q, which...

A uniformly charged spherical shell with surface charge density \sigma contains a circular hole in its surface. the radius of the hole is small compared with the radius of the sphere. what is the electric field at the center of the hole? I only know this question requires superposition of the...

E-field at various points from two "large" sheets 1.You've hung two very large sheets of plastic facing each other with distance d between them, as shown in the figure . By rubbing them with wool and silk, you've managed to give one sheet a uniform surface charge density n1 = -n_o and the other...

1. Two 10-cm-diameter charged rings face each other, 19.0 cm apart. Both rings are charged to + 50.0 nC. What is the electric field strength: At the midpoint between the two rings? At the center of the left ring? 2. E = q/4pi*ep_o*r^2 3. The online problem says this is from a...

Note this is more of a coursework theory question then a specific homework question. I am learning about E and B fields and electromagnetic waves. A common EM figure I find is the propagation of a photon where the E and B field propagate through space as seen in the following link...

Homework Statement A plane, harmonic, linearly polarized light wave has an electric field intensity given by {E}_z = {E}_0 cos pi*10^{15}*(t - x/.65c) while traveling in a piece of glass. Find (a) The frequency of the light. (b) Its wavelength. (c) The index of refraction of the...

1. When solving for electric flux, we dot product the area vector and the e-field vector. Why does area have a vector, and why is it perpendicular to the surface? Homework Equations phi=EAThe Attempt at a Solution Isn't area scalar; Is it because we just want to simplify the calculations so we...

Homework Statement Show that the electric field of a "pure" dipole can be written in the coordinate-free form E_{dip}(r)=\frac{1}{4\pi\epsilon_0}\frac{1}{r^3}[3(\vec p\cdot \hat r)\hat r-\vec p]. Homework Equations Starting from E_{dip}(r)=\frac{p}{4\pi\epsilon_0r^3}(2\cos \hat r+\sin\theta...

Hello everyone, My name is Fred and I'm a newcomer to the forum. I'm designing a very simple E-field sensor. So all I did was I got two styrofoam balls, wrapped them around with a few layers of aluminum foil to serve as charge collecting surfaces. Put both "sensors" on the ends of a thin wood...

Homework Statement \vec{E}=k(y^2\hat{x}+(2xy+z^2)\hat{y}+2yz\hat{z}) Here k is a constant with the appropriate units. Find the potential, using the origin as you reference point. Check our answer by computing \nabla V. [Hint: You must select a specific path to integrate along. It doesn't...

A few questions about electric field here: 1. Why do charges have to be on the outer surface of the conductor? 2. Why no charge on the inner surface of a hollow conductor? 3. If charges cannot be inside the conductor, how come the electric potential is constant throughout the conductor when...

I understand that electric field lines do not cross and a simple explanation is that it violates existence-uniqueness. I'm thinking there is a more complete explanation out there though. I think the answer lies in the realm of dynamical systems and non-linear dynamics, but it's been a whlie...

A line charge of uniform density \lambda forms a semi-circle of radius R0. Determine the magnitude and direction of the electric field intensity at the center of the semi-circle. I won't bother with uploading a picture I'm pretty sure you can picture this without. My trouble with this is I'm...

Homework Statement http://scitec.uwichill.edu.bb/cmp/online/P10D/Hunte/Electric%20fields_files/image122.jpg Find the Electric Field at Point P at height z over a uniformly charged disc of radius a with uniform charge Q. Homework Equations The Attempt at a Solution I'm looking...

Homework Statement E = 20 cos(\omegat-50x) \widehat{y} find H in free space? Homework Equations I used (\nabla X E ) = -dB/dt , and then integrated that expression with respect to t , for some reason I am getting an incorrect answer ?! The Attempt at a Solution the correct answer is H =...

Homework Statement http://img413.imageshack.us/img413/8307/prob01a.gif Determine the work done on a 0.5 µC charge moved from A to B. Homework Equations delta V= -integral(E*dl), aka the area under the curve on an E-field graph from A to B equals the potential difference. (Sorry...

A Charge of 3.2x10-6 sits .025 m from a charge of -1.6x-6 a. Calculate the magnitude and direction of the E-filed at a point directly between the 2 charges b. calculate the electric potential (relative to V = 0 at infinity) at the point directly between the two charges c. Calculate the...

The Problem is finding the E-field at a point P that is h distance from the center of a rectangle (along a line normal to its surface) with Length L and width W with a constant charge density sigma. This is for an intro E&M class that is supposed to use up through calculus 2, and we have not...

Homework Statement Determine the electric field intensity at the center of a small spherical cavity cut out of a large block of dielectric in which a polarization P exists. The Attempt at a Solution charge densitysurface = P(dot)n --> charge densitysurface = P(dot)r This is about as far as...

I am trying to calculate the E-field from a varying B-field. The B-field is from a current loop. \vec{B}(\vec{r},t)=\vec{B_{0}}(\vec{r})Sin(\omega t) where \vec{B_{0}}= http://www.netdenizen.com/emagnet/offaxis/iloopoffaxis.htm" Now since B is varying with time there should be an electric...