2022 Electric Charges and FieldsElectric Dipole – Field at Large Distance Easy Question 9 of 42 in Electric Charges and Fields

Two point charges $-q$ and $+q$ are placed at a distance of $L$, as shown in the figure [add image]. The magnitude of electric field intensity at a distance $R$ ($R\gg L$) varies as

A $\frac{1}{R^6}$
B $\frac{1}{R^2}$
C $\frac{1}{R^3}$
D $\frac{1}{R^4}$

The answer is C.

Solution

The two charges form an electric dipole. At a large distance ($R \gg L$): $E = \frac{kp}{R^3}\sqrt{1 + 3\cos^2\theta}$ $\therefore E \propto \frac{1}{R^3}$

Concept dipole field falls as 1/R³

Electric Charges and Fields in past papers

42 questions from this chapter have appeared across 23 exam years.