why dipole is used.can u send me the accurate definition of this.if we don't use dipole then what will happen

3Consider a pair of charges a small distance apart ( is the vector joining the negative charge to the positive charge and is illustrated in Figure  3.5 such that we can define

Figure 3.5: A pair of opposite charges are a distance apart. A dipole is formed by letting .

(3.14)

which is called the dipole moment. The resulting dipole potential is

If we assume that tends to zero, we may expand the second term in a Taylor series for small . Thus, we obtain

Hence,

(3.15)

The resulting electric field components are given by evaluating

in spherical coordinates. Hence

			(3.16)

Thus, falls off in magnitude like and vanishes when

. The electric field for a dipole is shown in Figure 3.6.

Figure 3.6: The electric field lines for an electric dipole.

 

 

 

Electric dipoles are very important . They exist everywhere around us . The presence of electric dipoles in molecules affect their chemical and physical behaviour . They also find use in antennas.