(ii) Infinite thin plane sheet of uniform surface charge density s
0
ˆ
2
σ
ε
E=
n
where ˆn  is a unit vector normal to the plane, outward on either side Rationalised 2023-24
40
Physics
(iii) Thin spherical shell of uniform surface charge density s
2
0
ˆ
(
)
4
q
r
R
r
ε
=
≥
π
E
r
E = 0
     (r   <   R)
where r is the distance of the point from the centre of the shell and R
the radius of the shell q is the total charge of the shell:  q = 4pR2s The electric field outside the shell is as though the total charge is
concentrated at the centre