By Sunil Bhardwaj

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When the molecules are placed in the electric field, there are the separation of electrons and the positive charges.

The molecules OR atoms, which are spherical, are now in the field are converted in to elongated form.

Polarisibility in a molecule

Now there will be separation of charges and they are pointing towards the respective plates. Now the dipole moment will be included inside the atom OR molecule, this dipole moment is called Induced Dipole Moment \({ \mu }_{ i }\).

The induced dipole moment is directly proportional to strength of electric field applied, \({ \mu }_{ i }\propto E\)

Where \({ \mu }_{ i }\) = induced dipole moment,

\(E\) = strength of the field applied

\(\therefore { \mu }_{ i } = \alpha E\)

Where, \(\alpha\) is polariseability of the molecule.

Polariseability of the molecule is defined as induced dipole moment per unit strength of the field applied,$$ \text { i.e. when } E = 1, \text { then } { \mu }_{ i } = \alpha $$