Point charge Definition and 363 Threads

  1. S

    Force on a point charge due to a rod

    Hvae a look at the diagram Caluclate the force on the point charge q, due to a uniformly charged rod of length L a distance x from the point charge q. Discuss the limit when L approaches infinity with lambda = Q/L fixed. Q = \lambda L dQ = \lambda dL Force of dQ on the point charge q...
  2. M

    E&M fields of a moving point charge

    Hi, I need help on the following question: Suppose a point charge q is constrained to move along the x-axis. Show that the fields at points on the axis to the RIGHT of the charge are given by \vec{E} = \frac{q}{4\pi\epsilon_0}\frac{1}{r^2}(\frac{c+v}{c-v})\hat{x} and \vec{B} = 0 What...
  3. N

    Parallel plates & Point charge ?

    1. parallel plate with capacitor of 20uF, plate is 0.5mm apart. Find 1. Area of each plate 2. potential difference if there's a change of magnitude of 30uC on each plate. 3. stored energy 4. electric field between the two plates 5. charge density on the plate. |_| |_|...
  4. F

    Point Charge Check? Point Charge Check!

    Point Charge Check!? Hi, I' did this problem but for some reason I'm not getting the right answer. If you could check to see where I made my mistake I'd really appreciate it. Thanks! The problem: A poitn charge (m=1 g) at the end of an insulating string of length 55 cm is observed to be...
  5. E

    Electric field on a point charge

    Hello guys, I have a question which I think I solved it right but I don't understand why the final answer is wrong. Here's the problem: Consider three charges as shown. k is 8.98755 * 10^9 N m^2/c^2. What is the electric field at a point 1.01 cm to the left of the middle charge? Ans. in N/C...
  6. G

    Equipotential Contours and Point Charge

    We haven't really covered this in class so I need some help. Assuming that these contours are those of a point charge at the origin, calculate the value of the charge in C. I tried using the equation kQ/R but that's wrong, I'm not even sure I'm using it right in fact. Any help? Thanks
  7. S

    Calculating Electric Flux Through a Square: Is Gauss' Law the Only Method?

    This is SUPPOSED to be easy but i seemingly find find it hard... A poin charge of +Q is places a distance d/2 above the centre of a square surface of side d. Find the electric flux through the square. so i know that E dA = EA (because the flux through the square is all at 90 degree...
  8. R

    Equilateral Triangle Point Charge Problem: Solving for the Unknown Charge

    Question: Three point charges, which are initially at infinity, are placed at the corners of an equilateral triangle with sides d. Two of the point charges have a charge of q. If zero net work is required to place the three charges at the corners of the triangle, what must the value be of the...
  9. G

    Plot the lines of the electric field between a small point charge

    I've been asked to complete electric field E and potential V inside and outside of a simple plate capacitor (the plates are infinitely large and the distance between the two plates is d.) My working is as follows. Inside the cap- E = \frac{ \sigma } { \epsilon_{o} } then potential V=Ed...
  10. J

    Point charge in an electric field

    an electron with a speed of 5.00 x 10^8 cm/s enters an electric field of magnitude 1.00 x 10^3 N/C, traveling along field lines in the direction that retards its motion. a) How far will the electron travel in the field before stopping momentarily b) how much time will have elapsed c) in the...
  11. J

    Calculating Electric Field with Point Charge and Hollow Sphere

    if u have an uncharged,perfectly conducting hollow sphere of thickness t and radius R, and a point charge Q is placed a distance D from the centre of the sphere so that R-t>D, what would the electric field, E, be? i just treated it the same as if Q was in the centre of the sphere and the...
  12. T

    Point charge in a hollow sphere

    Inside an uncharged, perfect conducting hollow sphere of thickness t and radius R, a point charge Q is placed at a distance D from the centre, where D<R - t. Need to derive a simple expression for the field outside the sphere. In a section passing through Q, sketch qualitatively the charge...
  13. M

    Point charge moving in a magnetic field question

    "A proton with a speed 10^7 m/s enters a region of a uniform magnetic field B = .8 T, which is into the page. The angle is 60º Find the angle 'fi' and distance d" "which is into the page." What the heck does that mean!?
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