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.