Spontaneous polarization occurs in ferroelectric materials. True False

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Question
Spontaneous polarization occurs in ferroelectric materials.
Options
A. True
B. False

Correct Answer

True

Materials and Components problems

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1. Assertion (A): Dielectric losses are proportional to tan ?.
Reason (R): tan ? = where ?_r^' and ?_r^" denote the real and imaginary parts of ?_r.
Options
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true

2. An electron shell corresponding to principal quantum number n can contain a maximum of
Options
A. n² electrons
B. 2n² electrons
C. 2n electron
D. n³ electron

3. In an hydrogen atom, an electron moves in the field of a proton. The stability of orbit requires equilibrium between coulomb's force and centrifugal force.
Options
A. True
B. False

5. An homogeneous dielectric material is subjected to an electric field E. If a small cavity is made inside the material, the electric field intensity inside and outside the cavity are different.
Options
A. True
B. False

6. For a core having a relative permeability ?_r, magnetic dipole moment per unit volume M and field strength H, the flux density B is
Options
A. B = ?_r (H + M)
B. B = ?₀ (H + M)
C. B = ?₀?_r (H + M)
D. B = ?₀?_r (H - M)

7. Figure shows a composite capacitor. If C_A, C_B, C_C are the capacitances of capacitors A, B, C, the overall capacitance C is
Options
A. C = C_A + C_B + C_C
B. C = (C_A + C_B) C_C
C. C =
D. C =

8. Assertion (A): In some materials, ?_r is independent of temperature while in others, ?_r depends on temperature.
Reason (R): If permanent dipoles are absent, ?_r varies with temperature.
Options
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not correct explanation of A
C. A is true but R is false
D. A is false but R is true

9. The direction of force an a conductor carrying current and lying in a magnetic field can be found by using
Options
A. Fleming's left hand rule
B. Fleming's right hand rule
C. Cork screw rule
D. Any of the above

10. The real part of complex dielectric constant and tan? for a dielectric are 2.1 and 5 x 10^-4 at 100 Hz respectively. The imaginary part of dielectric constant at 100 Hz is
Options
A. 1.05 x 10^-3
B. 2.1 x 10^-3
C. 5 x 10^-3
D. 1.05 x 10^-2

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