00:01
Hi, in the given problem there is an x -axis shown like this.
00:13
This is the origin.
00:16
Suppose point a is representing the origin at which we put a charge q.
00:24
As this is the origin, so x is 0 here.
00:28
Then there is another point, suppose if this is b at which we put a charge 2q.
00:35
Now the total gap between these two points is divided into three parts, each having a gap, each having a length of d.
00:49
So the total gap between these two points is 3d, means the position of this point b can be given as 3d.
01:00
Now in this problem we have to discuss the position of zero electric field at the x -axis whether it is in the region where x is less than zero or it is in the region where x is more than 3d or it is in a region where x is lying between 0 and 3d.
01:27
So, to discuss this position of the zero electric field, first of all, if we consider this position of zero electric field here in the region x less than zero and the point is supposed it to be p.
01:44
Then we know the electric field always goes away from the positive charge.
01:49
So the two electric fields here, ea, means due to the charge put at a point a, and electric field due to the charge put at point b, e b, both are in the same direction so they never can be added to give the resultant electric field to be equal to 0.
02:11
So zero electric field is never possible in this region where x is less than zero.
02:16
Now if you consider this observation point to be present here in a region x more than 3d, suppose this is point b.
02:26
Now again using the same rule as electric field goes away from a positive charge...