Physical Significance Of Dipoles

In most molecules, the centre’s of positive charges and of negative charges lie at the same place. Therefore, their dipole moment is zero.

CO2 and CH4 are of this type of molecules. However, they develop a dipole moment when an electric field is applied.

But in some molecules, the centres of negative charges and of positive charges do not coincide. Therefore they have a permanent electric dipole moment, even in the absence of an electric field. Such molecules are called polar molecules.

A water molecule, H2O, is an example of this type. 

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Some of these questions which may be asked in your Board Examination 2012-2013

Q1: what are the characteristic of charges acquired by the objects on rubbing against each other?

Q2: Who suggested first that there are two kinds of charges?

Q3: How can you show that there are two types of charges?

Q4: An ebonite rod is rubbed with the fur or wool. What type of charges do they acquire?

Q5: Is mass of body affected on charging?

Q6: What is the polarity of charge?

Answer these questions in comment box and help your friends