- #1
issacnewton
- 1,026
- 36
Hi
I am reading Griffiths EM book and I have some questions about the induced surface charge
from chapter 2 and 3.
In chapter 2 , he says that
[tex]\frac{\partial V_{above} }{\partial n}- \frac{\partial V_{below} }{\partial n}
= - \frac{\sigma}{\epsilon_o}...1)[/tex]
which is alright. Now few sections later, he says that , just outside conductor, we have
[tex] \sigma =-\epsilon_o \frac{\partial V_{above} }{\partial n} ...2)[/tex]
which is ok again. here the derivative of V inside the conductor is zero. Now
while discussing, method of image problem for a charge near a grounded conducting plane,
he again uses the same formula for the charge density. There we are considering a
plane , supposedly infinitesimally thin. Even though the plane is conducting,
we can't use the same arguments to arrive at eq. 2 from eq. 1. Can we ? What about
the other surface of this conducting plane ? Can we not talk of this part as below ?
and then the upper half (region where the actual charge is ) is above
I am reading Griffiths EM book and I have some questions about the induced surface charge
from chapter 2 and 3.
In chapter 2 , he says that
[tex]\frac{\partial V_{above} }{\partial n}- \frac{\partial V_{below} }{\partial n}
= - \frac{\sigma}{\epsilon_o}...1)[/tex]
which is alright. Now few sections later, he says that , just outside conductor, we have
[tex] \sigma =-\epsilon_o \frac{\partial V_{above} }{\partial n} ...2)[/tex]
which is ok again. here the derivative of V inside the conductor is zero. Now
while discussing, method of image problem for a charge near a grounded conducting plane,
he again uses the same formula for the charge density. There we are considering a
plane , supposedly infinitesimally thin. Even though the plane is conducting,
we can't use the same arguments to arrive at eq. 2 from eq. 1. Can we ? What about
the other surface of this conducting plane ? Can we not talk of this part as below ?
and then the upper half (region where the actual charge is ) is above