1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Capacitor problem help please

  1. Mar 28, 2012 #1
    capacitor problem ..help please!!

    1. The problem statement, all variables and given/known data
    Four metallic plates are placed as shown (attachment). Plate 2 is given charge Q whereas all other plates are uncharged initially .Plate 1 and 4 are earthed.The area(A) of each plate is same .
    q1) The charge appearing on the right side of plate 3 is--
    a) zero b) +Q/4 c) -3Q/4 d) Q/2

    q2) The charge appearing on the right side of plate 4 is--
    a)zero b) -Q/4 c) -3Q/4 d) -Q/4

    q3) The potential difference between plates 1 and 2 is--
    a) 3Qd/2εA b)Qd/εA c)3Qd/4εA d)3Qd/εA

    2. Relevant equations

    Well I tried taking the charge on left side of plate 2 to be q and the other side of it to be Q-q...then i proceed by applying charges on all plates by induction ...but get q=Q...which is not right ...help!!

    3. The attempt at a solution

    Attached Files:

    • p1.JPG
      File size:
      4.5 KB
  2. jcsd
  3. Nov 20, 2012 #2
    Re: capacitor problem ..help please!!

    Options of question 2 not correct and solution is that charge will flow from plate 4 to 1 due to high potential than 1. After equal potential at both plates charge +3Q/4 will be at 1 and +Q/4 will be at 4. so charge appearing on the right side of plate 3 will be +Q/4.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook