  # MCQs on Dielectric constants | Lorentz law | Numericals | Part 6

### This sets of objective questions or MCQs more focuses on Dielectric constants, lorentz law, contains numericals in part 6....

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## SET 1 mcqs of Dielectric constants, Lorentz law and numericals

1. A solid contains 6 x 1028 identical atoms /m3, each with polarizability of 2.85x 10-40F.m2 . Assuming internal field is given by Lorentz formula, the ratio of internal field to the applied field is
A.2.8095
B.0.2895
C.28.95
D.0.02895

Marks 2

2. For a parallel plate capacitor, if the value of capacitance is 4μF, applied voltage is 600V and the relative permittivity of the dielectric is 150 ; then energy stored in a capacitor is ----- and energy required in polarizing the dielectric is -------.
A.7.2 J , 0.715 J
B.72 J , 7.15 J
C.0.72 J , 0.715J
D.0.72J , 7.15 J

Marks 2

3. For a parallel plate capacitor, if the value of capacitance is 5μF, applied voltage is 1kV and the relative permittivity of the dielectric is 100 ; then energy stored in a capacitor is ----- and energy required in polarizing the dielectric is -------.
A.2.5 J , 2.475 J
B.25 W , 2.475J
C.2.5 J , 24.75J
D.25J , 24.75 W

Marks 2

4. A solid contains 7 x 1026 identical atoms /m3 , each with polarizability of 2 x 10-38Fm2. Assuming internal field is given by Lorentz formula, the ratio of internal field to the applied field is
A.21.155
B.0.21155
C.2.1155
D.0.021155

Marks 2

5. If an argon gas contains 2.7 x 1025 atoms / m3 at 00C and 1 atmospheric pressure and the diameter of argon atom is 3.84 AU(A0 ) ,then the relative dielectric constant is
A.1.0024
B.10.024
C.0.10024
D.0.0010024

Marks 2

6. If an hydrogen gas contains 8.4 x 1026 atoms / m3 at 00C and 1 atmospheric pressure and the radius of hydrogen atom is 0.53 AU(A0 ) ,then the electronic polarizability and relative dielectric constant are
A.1.66 x 10-41 F.m2 , 1.0157
B.166 x 10-41 F.m2 , 1.00157
C.1.66x 10-40 F.m2 , 1.00157
D.1.66 x 10-41 F.m2 , 1.00157

Marks 2

## SET 2 of

7. If a hydrogen gas contains 9.8 x 1026 atoms / m3 at 00C and 1 atmospheric pressure and the radius of hydrogen atom is 0.53 AU(A0 ) ,then the electronic polarizability and relative dielectric constant are
A.1.66x 10-41 F.m2 , 1.8
B.1.66x 10-41 F.m2 , 1.08
C.1.66x 10-41 F.m2 , 1.008
D.1.66x 10-40 F.m2 , 1.008

Marks 2

8. The polarization means -
i)The vector sum of all dipole moments per unit volume
ii) The surface charge density on the surface that produces exactly the same electrical field inside the material as all dipoles together
iii) The response of a dielectric material to an electrical field
iv) The net amount of charge in a unit volume

Select the correct answer using the codes given below
A.Only (i)
B.( i, ii, iii)
C.(ii,iii)
D.All of the above

Marks 2

9. A solid contains 4 x 1028 identical atoms /m3 , each with polarizability of 2.75 x 10-40 Fm2. Assuming internal field is given by Lorentz formula, the ratio of internal field to the applied field is
A.1.7
B.0.1702
C.0.1702
D.0.1702

Marks 2

10. If an argon gas contains 2.8 x 1025 atoms / m3 at 00C and 1 atmospheric pressure and the diameter of argon atom is 3.84 AU(A0) ,then the relative dielectric constant is
A.1.024
B.1.249
C.1.00249
D.1.0029

Marks 2

11. A solid contains 10 x 1028 identical atoms /m3 , each with polarizability of 1 x 10-40 Fm2. Assuming internal field is given by Lorentz formula, the ratio of internal field to the applied field
A.1.6042
B.1.64
C.1.46
D.1.42

Marks 2

12. All ferroelectric electric materials are ------- and ------- , but all piezoelectric materials are not --------. Select the correct answer using the codes given below
A.pyro electric and piezo electric ; pyro electric
B.piezo electric and pyro electric ; ferro electric
C.ferro electric and piezo electric ; pyro electric
D.None of these

Marks 2

13. The ------ effect is production of electricity by pressure whereas ------- effect is production of electricity by heating. Select the correct answer using the codes given below
A.pyro electric and piezo electric
B.piezo electric and pyro electric
C.ferro electric and piezo electric
D.ferro electric and pyro electric

Marks 2

14. Select the correct answer using the codes given below
Materials                                Application
1.Rochelle salt                          Phonograph
2.Barium titanate                       Amplifier
3.Quartz                                    Oscillator
A. Only 2
B. 1 and 2
C. 1 and 3
D. 2 and 3

Marks 2