Electric Definition and 1000 Threads

  1. F

    Net electric flux through a cylinder's surface

    Homework Statement Homework Equations ΦE = ∑Q enclosed / ε ∑Q enclosed = λh The Attempt at a Solution ΦE = ∑Q enclosed / ε ∑Q enclosed = λh ΦE = λh / ε
  2. F

    Electric flux through a wedge shaped block

    Homework Statement Homework Equations - The Attempt at a Solution Flux on opposite sides = 0 The answer is (E) , right ?
  3. S

    Modeling of two-phase flows in electric and magnetic fields

    Hi, Can anyone direct me to some literature that describes the numerical solution of full Maxwell's equations and Navier-Stokes equations for two-phase/multi-phase flows in coupled electric and magnetic fields. Thanks!
  4. B

    How come electric potentials have different signs?

    Homework Statement The textbook says to find the electric potential due to a point charge by moving a test charge from R to infinity, and integrating using the equation below. But when I integrate from infinity to R, the sign switches. Why is that? Both times, electric potential at V is 0...
  5. Muhammad Usman

    What is the Significance of the Electric field in a closed circuit

    Hi, I am confused about the electric field lines which are depicted mostly on the Internet as per conventional way. What I understand that the conventional current was due to positive charges which was wrong. Actual flow of the current was due to the negative charges or electrons. When the...
  6. S

    How does an Electric Bell use the Motor Effect?

    I need help in explaining how electric bell uses motor effect.
  7. C

    How Much Voltage Is Needed to Suspend Charged Water Droplets?

    Homework Statement You intend to suspend water droplets in mid-air to understand rainfall. You give the droplets a small positive charge, and keep them suspended by an electric field upwards. The experiment consists of two horizontal metal plates, separated by 9.3m. The water droplets have a...
  8. Helmy

    Question about Electric Field lines (MCQ)

    *This is a question in an assignment that i have to submit. 1. Homework Statement Two imaginary spherical surfaces of radius (R) and (2R) respectively surround a positive point charge (Q) located at the center of the concentric spheres. What is the number of electric field lines (N2) going...
  9. P

    When is an Electric Field eqn set as - or + ?

    Homework Statement Two point charges are placed on the x axis.(Figure 1)The first charge, q1 = 8.00 nC , is placed a distance 16.0 m from the origin along the positive x axis; the second charge, q2 = 6.00 nC , is placed a distance 9.00 m from the origin along the negative x axis. Find the...
  10. P

    Electric field due to current carrying conductor

    Does static charge near to a constant current carrying conductor experience force on it? I am asking this question because i have learned that electric field and mangnetic field are same thing but viewing differently with respect to the frame of reference...when a positive test charge moves (...
  11. M

    Electric potential at an unknown point

    Homework Statement The electric field inside a parallel plate capacitor is measured to be E= -3500 N/C i. The electric potential at point XA = 3.00 m is measured to be 1500V. What is the electric potential at point XB = 0 m? Homework Equations V=E⋅s The Attempt at a Solution I think I need to...
  12. SirChris93

    How to find vectors and bisectors of an electric field

    <Moderator's note: User has been warned not to remove the template, and upload images instead of linking to an external site.> I'm very lost here, I don't know where to begin. My instructor is little help, the notes he gives are not even useful, and I cannot find anything in the book.We were...
  13. A

    When Electric Field is 0 is potential also 0?

    So here is how my book defined electric potential. If you take a charge, it will have a corresponding electric field associated with it. If you put another charge in that electric field, an electrostatic force will act on it and give it kinetic energy. This kinetic energy can't come from thin...
  14. F

    Understanding the Relationship between Electric Field Line Distance and Strength

    Supposedly the strength of the electric field is is related to the distance between electric field lines. I have two questions about what exactly this means. 1.) What is the distance between electric field lines? Is it just the distance between two points on adjacent electric field lines that...
  15. PKM

    What should be the electric field intensity inside a sphere

    If the force acting between two point charges were proportional to \frac{1}{r^ 3}, instead of \frac{1}{r^ 2}, what would be the electric field intensity and charge density inside a charged solid metallic sphere?
  16. L

    Three parallel plates -- find the electric field

    Homework Statement Find the field at A. Homework Equations ##\oint E\cdot dA = Q_{enclosed}/\epsilon_0## The Attempt at a Solution My first intuition was to do a Gaussian cylinder from A to the middle of the bottom plate. My logic is that the field inside the bottom plate is 0, so I'd have...
  17. F

    Flux with a non-uniform electric field

    If the electric field is uniform, the electric flux passing through a surface of vector area S is , where E is the electric field (having units of V/m), E is its magnitude, S is the area of the surface, and θ is the angle between the electric field lines and the normal (perpendicular) to S...
  18. sam charlton

    Supercapacitors: The Future of High-Performance Energy Storage?

    Hello, what is the consensus on using super capacitors to power a 500w electric bike motor. cheap and innovative alternative to li-po batteries or explosion between thighs waiting to happen? the plan is to create something like this: i will use a 24V motor...
  19. sam charlton

    Can a 24V 30A Dimmer Switch Handle the Starting Current of a 500W 24V Motor?

    Hello, I'm currently constructing an electric bicycle using a 500w 24v motor, 2X24v 7ah batteries (maybe 4 later on). I bought a 24v 30a dimmer switch to use as a "throttle". During the intitial test (on a table, not on the bike!) It worked absolutely fine for 2 minutes, but then began to smoke...
  20. F

    Electric Field from Long Hollow Cylinder

    Homework Statement Consider the hollow cylinder from Exercise 1.59. Use Gauss’s law to show that the field inside the pipe is zero. Also show that the field outside is the same as if the charge were all on the axis. Is either statement true for a pipe of square cross section on which the...
  21. F

    Electric Flux in a Closed Space: Volume, Area & Benefits

    I believe the electric flux within a closed space can be found with the equation phi = Q/ε0. Can this be used for volume and area, or just volume? Also what good does this do. Why would I want to know the electric flux of something?
  22. M

    Question about charged particle in an electric field

    Question: A) A small charged sphere is attached to a thread and placed in an electric field. The other end of the thread is anchored so that the sphere is in a static situation when placed in the field. If the thread is horizontal, find the magnitude and direction of the electric field. The...
  23. F

    Electric potential outside an insulator in a uniform field

    Homework Statement An Ohmic material with some conductivity has a uniform current density J initially. Let's say the current is flowing in the direction of the z-axis. A small insulating sphere with radius R is brought inside the material. Find the potential outside the sphere. Homework...
  24. P

    I EM Radiation of "Permanent" Molecular Electric Dipoles

    Suppose I were to subject a polar molecule to a high-frequency electric field. The polar molecule responds to the high-frequency electric field and thus it has a time-varying electric dipole moment vector. If we treated this as a classical electric dipole, it would be expected to radiate some of...
  25. F

    How to Calculate Electric Field from Rods?

    Homework Statement (a) Two long, thin parallel rods, a distance 2b apart, are joined by a semicircular piece of radius b, as shown in Fig. 1.44. Charge of uniform linear density λ is deposited along the whole filament. Show that the field E of this charge distribution vanishes at the point C...
  26. G

    What happens when you insulate the rails of a DC electric train?

    a DC electric train or tram uses a single overhead wire unlike it's AC counterparts like trolleys which use two, so if there is only a single overhead wire I assume that the return wire or let's call it ground for the electric DC train are the rails correct? Does this mean that it is important...
  27. Roverse

    An equilateral triangle's electric field at its center

    Homework Statement Three 18-cm long rods form an equilateral triangle. Two of the rods are charged to +10 nC, and the third to - 10 nC. What is the electric field strength at the center of the triangle? Homework Equations $$ \vec{E} = \frac{k*q}{r^2} $$ The Attempt at a Solution 1. Draw...
  28. Likith D

    Electric field experienced by a uniformly charged spherical shell due to itself

    The electric field experienced by the points on the surface of the shell is put out as KQ/R^2 where Q is charge on shell and R is radius of shell... But the gaussian surface corresponding to the case intersects the sphere, which means there are non-infinitesimal charge quantity sitting on the...
  29. S

    How an electric field is absorbed by a dielectric

    when a em waves strikes a dielectric the atoms vibrate in response to the electric field and if the frequency matches the resonant frequency the Lorentz oscillator the electric field is absorbed how a field can be absorbed we know the em field contain energy how is the em field destroyed is some...
  30. V

    Electric Field of a solid sphere of non-uniform surface density

    A solid sphere has surface charge density, Rho (r) Rho(r) = k 1 ( 0 < r < a) k2 x ( a < r < R) 2) Find the electric field in all region i.e 1) r < a and 2) a < r < R and 3 ) R < The attempted solution and the question with the diagram is attached below Could the answer be verified...
  31. D

    I Charged black hole - static electric field lines

    Where do the static electric field lines appear to originate from a charged black hole, non rotating, Reissner–Nordström metric? I've had a number of qualified physicists say they appear to come from the center of the black hole, but people on these forums have said that doesn't make sense...
  32. A

    Electric Potential vs Electric Potential Energy

    So in my physics textbook a problem is stated. We are given an external electric field directed downwards of 150N/C. We are then told that an electron is released in the electric field and it moves upwards 520m. Finally we are asked to calculate the change in electric potential energy of the...
  33. Benjamin

    Calculating Electric Field from Force on a Point Charge

    Homework Statement What is the electric field at a point when the force on a 1.20 µC charge placed at that point is = (3.0 î -5.0 ĵ) × 10-3 N? Homework Equations E = KQ/d^2 The Attempt at a Solution I'm having trouble visualizing the question. I attempted to draw it out, but its not making...
  34. G

    What is the Simplified Equation for a Uniform Electric Field?

    Homework Statement [/IMG] Homework Equations See Below The Attempt at a Solution Maybe my answer is right but not simplified enough. But if it is I am having trouble seeing the mathematical equivalency. Please help. Thanks in advance!
  35. Matt Chu

    Angle of escaping electric field lines

    Homework Statement Two charges 2q and -q are located at x = 0 and x = a respectively. There are field lines extending from the positive charge and lines going inwards to the negative charge. Some of these lines go from the positive charge to the negative, but some go off to infinity from the...
  36. Brystephor

    Electric field magnitude between two charged disks problem

    Homework Statement Consider two thin disks, of negligible thickness, of radius R oriented perpendicular to the x axis such that the x axis runs through the center of each disk. (Figure 1) The disk centered at x=0 has positive charge density η, and the disk centered at x=a has negative charge...
  37. M

    How Do You Calculate Electric Field Strength and Direction?

    Homework Statement The diagram is attached. What is the strength of the electric field at the position indicated by the dot in Figure 1? What is the direction of the electric field at the position? Specify the direction as an angle measured clockwise from the positive x axis. Homework...
  38. T

    How exactly does the electric force act?

    greeting How exactly the electric force acts .The definition of force is In physics, a force is any interaction that, when unopposed, will change the motion of an object. as the electron circulates around the nucleus of the atom because of that I do not see how that force acts .
  39. G

    Help finding component of electric force

    Homework Statement [/IMG] In this problem I am trying to understand the solution for finding the net force on charge 3 due to charge 1. However, I am getting stuck already on F31x. Homework Equations F=kqq/r^2 The Attempt at a Solution I found theta by tan-1(0.5/1)=26.565degrees r= sqrt...
  40. L

    Calculate a charge distribution given an electric potential.

    Homework Statement Find the distribution of charge giving rise to an electric field whose potential is $$\Phi (x,y) = 2~tan^{-1}(\frac{1+x}{y}) + 2~tan^{-1}(\frac{1-x}{y})$$where x and y are Cartesian coordinates. Such a distribution is called a two-dimensional one since it does not depend on...
  41. M

    Electric field vector in component form

    Homework Statement A -12nC charge is located at (x,y) = (1.0cm, 0cm). What are the electric fields at the positions (x,y) = (5.0cm, 0cm), (-5.0cm, 0cm), and (0cm, 5.0cm)? Write each electric field vector in component form. Homework Equations E=k(q/r2) The Attempt at a Solution I was able to...
  42. L

    Finding the electric field between two parallel plates

    Homework Statement Hi everyone! This is the homework problem I'm struggling with! Initial velocity = 107 meters per second The particle is an electron, so: Charge = -1.6 x 10-19 coulombs Mass = 9.11 x 10-31 kilograms Homework Equations Kinematic formula x = vot + 1/2 at2 Newton's law...
  43. lawsonfurther

    Can there be an electric field inside an insulator?

    Just as the title asks, I wonder if there can be any electric field inside an insulator when a point change is placed near it. If so, why?
  44. A

    Confusion regarding Electric Potential Energy and Work

    Hi everyone. I've been doing a lot of reading regarding electric potential and electric potential energy. Unfortunately, I have a lot of confusion regarding this topic, as I keep receiving different information. My main confusion is regarding the signs, positive or negative, of work and it's...
  45. S

    Find the electric field at the point 20cm above the centre

    Homework Statement Hi guys, I was hoping I could get some help on this question! The question: "Find the electric field at the point 20 cm above the center of the square made of 4 charged rods of L = 20cm and Q=1mc each. Homework Equations I believe E = (KQ)/r^2 is the only equation needed...
  46. H

    How do you calculate Electric Potential Energy in a Square?

    Four identical particles, each having charge q and mass m, are accelerated from rest at the vertices of a square of side L. How fast is each particle moving when their distance from the center of the square doubles? I used the Conservation of Energy => Kf= -deltaU = Ui-Uf 4(mv^2 /2) = kq^2...
  47. B

    Calculate final velocity of electric particle

    Homework Statement A particle of mass 7.3 × 10−5 g and charge 24 mC moves in a region of space where the electric field is uniform and is 6.3 N/C in the x direction and zero in the y and z direction. If the initial velocity of the particle is given by vy = 4.1 × 105 m/s, vx = vz = 0, what is...
  48. starstruck_

    Calculating electric field strength

    Homework Statement A cylinder of radius R= cm 1.2 and length L= 51 cm has a charge Q=2.3 μC spread uniformly along its surface (and not on its flat ends). a) Calculate the electric field strength a distance d=4 mm from the cylinder’s surface (not near either end) b)Calculate the electric...
  49. R

    Electric field at the surface of a spherical shell?

    What is the value of electric field at the surface of a spherical shell?
  50. C

    Electric field between two cylinders in a vial

    Homework Statement Hello everyone, I am writing here regarding a doubt I have about electric fields. Our set up consists on two rod shape electrodes in a cylindrical glass vessel separated by 6 mm from each other, with one of the electrodes grounded (electrodes dimensions: 0.5 mm diameter and...
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