Two shorts dipoles ( $\mathrm{A}, \mathrm{B}$ ), A having charges $\pm 2 \mu \mathrm{C}$ and length 1 cm and B having charges $\pm 4 \mu \mathrm{C}$ and length 1 cm are placed with their centres 80 cm apart as shown in the figure. The electric field at a point P , equi-distant from the centres of both dipoles is $\_\_\_\_$ N/C.