question_answer

The electric field strength due to a dipole depends upon distance r as

A)  \[E\propto \frac{1}{r}\]               

B)         \[E\propto \frac{1}{{{r}^{2}}}\]

C)  \[E\propto \frac{1}{{{r}^{3}}}\]                

D)         \[E\propto \frac{1}{{{r}^{4}}}\]

Correct Answer: C

Solution :

The electric field strength due to a dipole at any general point P (r, \[\]) is \[E=\frac{1}{4\pi {{\varepsilon }_{0}}}\frac{p}{{{r}^{3}}}\sqrt{(1+3{{\cos }^{2}})}\propto \frac{1}{{{r}^{3}}}\]