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The best definition of polarisation is
Explanation: The polarisation is defined mathematically as the electric dipole moment per unit volume. It is also referred to as the orientation of the dipoles in the direction of applied electric field.
Calculate the polarisation vector of the material which has 100 dipoles per unit volume in a volume of 2 units.
Explanation: Polarisation vector P = N x p, where N = 100 and p = 2. On substituting we get P = 200 units.
Polarizability is defined as the
Explanation: Polarizability is a constant that is defined as the ratio of elemental dipole moment to the electric field strength.
Calculate the energy stored per unit volume in a dielectric medium due to polarisation when P = 9 units and E = 8 units.
Explanation: The energy stored per unit volume in a dielectric medium is given by, W = 0.5 X PE = 0.5 X 9 X 8 = 36 units.
Identify which type of polarisation depends on temperature.
Explanation: The electronic, ionic and interfacial polarisation depends on the atoms which are independent with respect to temperature. Only the orientational polarisation is dependent on the temperature and is inversely proportional to it.
Calculate the polarisation vector in air when the susceptibility is 5 and electric field is 12 units.
Explanation: The polarisation vector is given by, P = ε0 x χe x E, where χe = 5 and ε0 = 12. On substituting, we get P = 1 x 5 x 12 = 60 units.
In isotropic materials, which of the following quantities will be independent of the direction?
Explanation: Isotropic materials are those with radiate or absorb energy uniformly in all directions (eg. Isotropic antenna). Thus it is independent of the direction.
The total polarisation of a material is the
Explanation: The total polarisation of a material is given by the sum of electronic, ionic, orientational and interfacial polarisation of the material.
In the given types of polarisation, which type exists in the semiconductor?
Explanation: The interfacial type of polarisation occurs due to accumulation of charges at the interface in a multiphase material. This interface or junction is found in a semiconductor material.
Solids do not have which type of polarisation?
Explanation: Solids possess permanent dipole moments. Moreover they do not have junction like semiconductors. Thus, solids neglect the interfacial and space charge polarisation. They possess only electronic, ionic and orientational polarisations.