Question

Two charges +Q and -2Q are located at points A and B on a horizontal line as shown
The electric field is zero at a point which is located at a finite distance

• A. On the perpendicular bisector of AB
• B. Left of A on the line
• C. Between A and B on the line
• D. Right of B on the line

Answer 1

Answer: (B)

Left of A on the line
Answer is B.
Because one charge has twice the magnitude of the other were looking for locations twice as far from the 2Q charge (point B) as from the +Q charge. There is one such location between the charges and another to the left of the +Q charge (point A).
Hence, The electric field is zero at a point left of on the line which is located at a finite distance.