Question

A point charge $+ q$ is located at the origin, and a point charge $+4 q$ is located at $x=a$, where a is positive. Which of the following statements is true?

• A. Between the two charges the electric field can be zero at x = a / 3
• B. The electric field can be zero at x =- a
• C. Electric field can never be zero on x axis
• D. The electric field is maximum at a point between the two charges

Answer 1

Answer: (A)

Both charges are positive so electric field is zero in between them

$\frac{ kq }{ x ^{2}}=\frac{ k 4 q }{( a - x )^{2}} $
$ \Rightarrow x =\frac{ a }{3}$