Four electrical charges are arranged on the corners of a 10 cm square as shown. What would be the direction of the resulting electric field at the center point P?

$E_1=E_4=2E_2=2E_3$

Resultant of $E_4 and E_2$ is towards fourth charge.

Resultant of $E_1 and E_3$ is towards third charge.

Now, horizontal components will be canceled, and net field will be upward. Angle between them =90 and $Enet=2E\cos \frac{\theta }{2}=2E\cos \frac{90}{2}=\sqrt{2}E upwards$