Two plates are placed 15 cm apart connected to a 4500 V supply.

(a)    What is the strength of the uniform field between the plates?

(b)   What is the force acting on a 6 nC test charge between the plates?         

(a) E = V/d = 4500 V ¸ 0.15 m (P) = 30 000 V/m (P)

(b) E = F/Q Þ F = EQ = 30 000 V/m ´ 6.0 ´ 10^-9 C (P) = 1.8 ´ 10^-4 N (P)