00:02
Hi, there is a square in the given problem.
00:07
Here it is like this.
00:10
And eight different charges are arranged over it.
00:16
First of all, suppose it is named as a, b, c and d, and the midpoints of its sides are named as e, f, and and g and h.
00:42
Now the charges put over there are, first of all, this is plus 3 q at a, then here this is plus q.
00:55
At f, at b, this is minus 5q.
01:01
At g this is minus 2 q at c this is plus 3 q at h this is plus q at d this is minus 5 q and at e this is just plus q now we have to find net electric field at the center of this square and we know the center means the point of intersection of its diagonals here.
01:41
So if we find net electric field here at this point, so there are various electric fields due to all these various charges.
01:52
So using the rule that electric field always goes away from the positive charge and approaches the negative charge.
01:59
First of all, electric field at this center due to the charge put at a, that will be going away like this and due to that put at c and that is the same charge so it will also be going away.
02:15
So these two electric fields which are named as ea and e c as the distance of this center from all the vertices is the same.
02:26
So we can say e a is equal to ec and directed opposite to each other so they cancel out now we look for the electric fields at the same center due to the charge put at b and that is towards the negative charge here and similarly due to that put at d that will also be directed towards the negative charge and these these two electric fields are e b and e d.
03:13
Here again as the charges are same and the distance is also same.
03:17
So e b is equal to e d and directed opposite.
03:31
So they also cancel out.
03:40
And this we are using, we are doing using the expression for electric field.
03:45
We should also mention it here...