Electric field inside an insulating cylinder with radius
R
, where its axis is on
z
-axis and carrying polarization
vec(P)=Phat(x)
is : [1]
(P)/(3\epsi _(0))hat(x)
[2]-(P)/(3\epsi _(0))hat(x)
[3]
-(P)/(2\epsi _(0))hat(x)
[4]
(P)/(2\epsi _(0))hat(x)