Answer:
E = 400 V/m
Step-by-step explanation:
It is given that, for a parallel plates :
Potential difference, V = 12 volts
Separation between the plates, d = 3 cm = 0.03 m
The relation between the electric field and the electric potential is given as :
E = 400 volts/m
So, the strength of the electric field is 400 V/m.