65.
(a) The direction of the electric field at P
1
is away from q
1
and its magnitude is
E
=
q
4πε
0
r
2
1
=
(8.99
× 10
9
N
·m
2
/C
2
)(1.0
× 10
−7
C)
(0.015 m)
2
= 4.0
× 10
6
N/C .
(b)
E = 0, since P
2
is inside the metal.
65.
(a) The direction of the electric field at P
1
is away from q
1
and its magnitude is
E
=
q
4πε
0
r
2
1
=
(8.99
× 10
9
N
·m
2
/C
2
)(1.0
× 10
−7
C)
(0.015 m)
2
= 4.0
× 10
6
N/C .
(b)
E = 0, since P
2
is inside the metal.