Dielectrics
1. In a dielectric medium subjected to a unifom electric ield E, dipoles of
polarizability a are created. If the number of dipoles are N then show that the
macroscopic electric field within the specimen, E, is related to the applied field E as
1-Na
E E(Use Claussius- Mossotti relation)
2Nss
2. A dielectric material of constant x is inserted between the plates of a charged
parallel
plate capacitor. Show that the fractional loss in energy within the dielectric is given
byl-Y).
3. Aparallel plate capacitor of area Aand separation between plates d
inserted between its plates. If the thickness of the metal plate is b(< d)hasthena metal plate
show that
the resultant capacitance is given by C= "
d-b
4. If the molecular dipoles in a 1g m radius water drop are
direction, calculate the polarisation of the water drop. Dipolepointed in the same
moment of wat
molecule is 6x10Cm.
5. Assuming that the polarisability of Kr atom is 2.18x 100 Fm-2, calculate its
dielectric constant given the mass number is 84 and density is 3.19
6. Find the total polarisability of CO, if its susceptibility is 0.985x10. IDensity of CO:
is 1.977 Kgm-3
7. On being polarised an oxygen atom shows a dipole moment of
distance of the center of the -ve charge cloud from the nucleus 0.5x10 C-m. If the
is 4x10"m, calculate
the polarisability of oxygen.
8. A parallel plate capacitor without a dielectric is
charged such that the surface charge
density on the plates is 10" C-m-2. Ifa slab of a material
inserted between the plates, calculate the polarisation in with
the
dielectric constant 10 is
material and the electric
field due to induced surface charge on the dielectric.
9. A dielectric material has one
ons species having an atomic polarizability value of
Cmiv. It is found that when the dielectric sample 100
is kept ina uniform electric field,
the field reduces to one tenth of its original value.
unit volume of the Estimate the number of atoms per
material.
10. Electronic polarisability of Sulphur is 3.28 x 10
constant of Sulphur if the density and atomic weight ofF-m. Calculate the dielectric
Sulphur are 2.08 x 10' kg-m
and 32 respectively.
11, For a given electron, I 3 and s 0.5. Assuming j = ts, estimate the
factor. Lande's g
12. Estimate the Curie's constant for the data
additional given in the previous problem with the
data being the number of atoms present
13. Show that the Larmor per unit volume being 10".
frequency associated with
twice the frequency associated with the orbital motion. the spin motion of the electron is
14. Estimate the possible lengths of
the total angular momentum
whose | =l and s 0.5. vector for an electron
15. Show that the
for spin motion.gyromagnetic ratio
for an orbiting electron is half the
value for the one
