Assertion (A): Ferroelectric materials have spontaneous polarization. Reason (R)

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Question
Assertion (A): Ferroelectric materials have spontaneous polarization.
Reason (R): Above curie temperature, ? = for ferro-electric materials.
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

Correct Answer

Both A and R are true but R is not correct explanation of A

Explanation

Both A and R are correct. Spontaneous polarization vanishes above ferroelectric curie temperature.

Materials and Components problems

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1. Assertion (A): In imperfect capacitors, the current does not lead the applied ac voltage by 90�.
Reason (R): When subjected to ac fields, the dielectric constant can be expressed as ?^'_r - j?^"_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. The number of valence electrons in donor impurity are
Options
A. 5
B. 4
C. 3
D. 1

3. When an electric field E is applied to solid and liquid insulating materials, the internal field E_i acting at the location of atom is such that
Options
A. E_i = E
B. E_i > E
C. E_i < E
D. E_i may be equal to or less than E

4. Assertion (A): Power loss in a conductor of resistance P = I²R.
Reason (R): When a conductor is carrying current with current density J as a result of applied field E, then heat developed/m³/ second = JE.
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

5. Which of the following are donor impurities?
1. Gold
2. Phosphorus
3. Boron
4. Antimony
5. Arsenic
6. Induim
Select the correct answer using the following codes
Options
A. 1, 2, 3
B. 1, 2, 4, 6
C. 3, 4, 5, 6
D. 2, 4, 5

6. Which capacitor-store higher amount of energy?
Options
A. Air capacitor
B. Paper capacitor
C. Mica capacitor
D. Plastic film capacitor

7. If the temperature of an extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then
Options
A. the majority carrier density is doubled
B. the minority carrier density is doubled
C. the minority carrier density becomes 4 times the original value
D. both the majority and minority carrier densities double

8. Assertion (A): Magnetic susceptibility of diamagnetic materials is much less than that of paramagnetic materials.
Reason (R): For diamagnetic as well as paramagnetic materials, ?_r is nearly equal to 1.
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. Which element exhibits the property of inertia?
Options
A. Resistance
B. Capacitance
C. Inductance
D. Both resistance and inductance

10. In a true valence crystal, the bonding between the atoms is accomplished by the sharing of valence electrons.
Options
A. True
B. False

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