Question

Find the met force on the charge which placed at
o
​

Answer 1

Explanation:

Let the electric field E is zero at a point P between the two given charges , at a distance x from the charge Q which is at the origin .

at point P, electric field due to Q at origin

E

1

=KQ/x

2

at point P, electric field due to 4Q which is at a distance d from Q at origin

E

2

=4KQ/(d−x)

2

as E

1

and E

2

are in opposite direction due to two positive charges and electric field is zero at point P , therefore

E

1

=E

2

or KQ/x

2

=4KQ/(d−x)

2

or 4x

2

=(d−x)

2

or x=d/3 or −d

but x=−d , it means point P is not in between the two given charges of Q and 4Q so it is not possible as both of the charges will repel it in same direction, so the net force will not be zero.

now if we put a positive test charge q at point P , force on it

F=qE=q×0=0