Question

Two electric charges $Q$ and $4Q$ are separated by a certain distance. If the electric field intensity at $Q$ is E, the electric field intensity at the other charge is :

• A. $4E$
• B. $E/4$
• C. $E/2$
• D. $2E$

Answer 1

Answer: (B)

$E/4$

Electric field intensity due to a charge $Q$ at a distance $d$ is given by

$E^{\prime }=\frac{1}{4\pi {ϵ}_0}\frac{Q}{d^2}$

Field due to $4Q$ at $Q$ is $E=\frac{1}{4\pi {ϵ}_0}\frac{4Q}{d^2}$

Similarly, field due to $Q$ at $4Q$ is $E^{\prime }=\frac{1}{4\pi {ϵ}_0}\frac{Q}{d^2}=\frac{E}{4}$