- #1
gracy
- 2,486
- 83
Homework Statement
A,B and C are three concentric metal shells of radii a,2a and 3a .Shell A is the innermost and shell C is the outermost .Shell A is given a charge q and C is earthed.Find the final potential of shell B.
Homework Equations
##V##=##\frac{Kq}{r}##
The Attempt at a Solution
Charge q' is supplied from Earth to shell.
Then charges will be induced
Now we have to find q'
Potential of shell C should be zero.
##\frac{K(q'+q)}{3a}## - ##\frac{Kq}{3a}## +##\frac{Kq}{a}## - ##\frac{Kq}{a}## +##\frac{Kq}{2a}## =0
##\frac{K(q'+q)}{3a}## - ##\frac{Kq}{3a}## +##\frac{Kq}{2a}## =0
##\frac{K(q'+q)-Kq+\frac{3Kq}{2}}{3a}##=0
##K(q'+q)####-Kq##+##\frac{3Kq}{2}##=0
##\frac{2K(q'+q)-2Kq+3Kq}{2}##=0
##2K(q'+q)##-##2Kq##+##3Kq##=0
##2K(q'+q)##+##Kq##=0
##2K(q'+q)##=##-Kq##
##2(q'+q)##=##-q##
##q'+q##=##\frac{-q}{2}##
##q'##=##\frac{-q}{2}##-q
##q'##=##\frac{-3q}{2}##
Now by putting value of q' we can find potential of shell B by all the charges present.Am I right till here?