CBSE Class 12-science Answered

In most molecules, the centres of the positive and the negative charges lie at the same point. So, their dipole moment is zero. CO₂ and CH₄ are molecules of this type. However, they develop a dipole moment when an electric field is applied. However, in some molecules, the centres of the positive and negative charges do not coincide. These molecules therefore have a permanent electric dipole moment even in the absence of an electric field. Such molecules are called polar molecules. The water molecule (H₂O) is an example of this type. Various materials give rise to interesting properties and important applications in the presence or absence of an electric field.