Question

Four charges +q, +2q, +q and –q are placed at the corners of a square. Calculate the electric field at the intersection of the diagonals of the square of side10 cm if q = 5/3 × 10⁻⁹C.

Answer 1

Refer to the attachment :-
Here four charges +q , -q , +q , +2q are given  along with diagonal side 0.1 m .
Now , electric field at the intersection point of the diagonals of the square , so the net electric field . 

E = k . ( + q - q + q + 2q ) / r² 
E = k .3q / r²
Now put the values .
E = 9 × 10⁹ [ 3 × $\frac{5}{3}$ × 10⁻⁹ ] / (0.1 /√2)²
E = (2 × 9 × 5 ) / 10⁻²
E = 9000 N/C . 


Hope it Helps .