Charges q, 2q, 3q and 4q are placed at the corners A, B, C and D of a square as shown in the following figure. The direction of electric field at the centre of the square is along

Options

A. AB
B. CB
C. AC
D. DB

Answer

B

Explanation

The resultant of the field due to the charges at A & C is `(2q)/(4 pi e_0 x^2)` along CA and the resultant of the field due to the charges at B & D is `(2Q)/(4 pi e_0 r^2)` along DB
`implies` Net field `=(2 sqrt2 q)/(4 pi e_0 r^2)` along CB.