A charge of 4.00 mC is placed at each corner of a square 1.05 m on a side. Determine the magnitude and direction of the force on each charge.

1 answer

q1, q2, q3,q4 –from the lower left corner – counterclockwise.
Origin of the coordinate system is at the corner where q1 is located.

F12=k•q1•q2/a² =
=9•10^9•4•10^-3•4•10^-3/1.05²=
= 130612 N
F12x=0, F12y= - 130612 N.

F13=k•q1•q3/ (a√2)² =
=9•10^9•4•10^-3•4•10^-3/1.05²•1.41=
= 92633N
F13x=F13y= - 92633 •cos45= - 65491 N.

F14=k•q1•q4/a² =
=9•10^9•4•10^-3•4•10^-3/1.05²=
= 130612 N
F14x= - 130612 N, F14y =0 N.

F1x= F12x+ F13x +F14x =0 - 65491- 130612 = - 196103 N,
F1y= F12y+ F13y +F14y = - 130612 – 65491 -0= - 196103 N.
F1=sqrt(F1x² + F1y²) =sqrt(196103² + 196103 ²) =277331 N.
tanα = F1y/ F1x= 1
=> along the diagonal of the square, away from each charge.
The same force acts on each charge