Materials and Components problems
- 1. In paramagnetic materials
Options- A. permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible
- B. permanent magnetic dipole do not exist
- C. permanent magnetic dipoles exist and the interaction between neighbouring dipoles is very strong
- D. permanent magnetic dipole moment may or may not exist Discuss
Correct Answer: permanent magnetic dipoles exist but the interaction between neighbouring dipoles is negligible
Explanation:
In paramagnetic materials interaction between neighbouring dipoles is negligible.
- 2. The apparent capacitance at a high angular frequency ? of an air cored capacitor having capacitance C and inductance L is given by
Options- A.
- B.
- C.
- D.
Discuss
Correct Answer:
Explanation:
The combination can be represented as L and C in series.
.
Therefore, 
.
- 3. Ferroelectric materials are those which
Options- A. cannot be polarized
- B. have a permanent polarization
- C. have ae equal to zero
- D. have ?p = 0 Discuss
Correct Answer: have a permanent polarization
Explanation:
Ferroelectric materials have permanent polarization.
- 4. At room temperature, the current in intrinsic semiconductor is due to
Options- A. holes
- B. electrons
- C. ions
- D. holes and electrons Discuss
Correct Answer: holes and electrons
Explanation:
Both electrons and holes contribute to flow of current in semiconductors.
- 5. Assertion (A): Atomic number of sodium is 11.
Reason (R): Sodium has a body centred cubic lattice.
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 Discuss
Correct Answer: Both A and R are true but R is not correct explanation of A
Explanation:
Atomic number is not dependent on lattice structure.
- 6. Which of the following are donor impurities?
- Gold
- Phosphorus
- Boron
- Antimony
- Arsenic
- Induim
Options- A. 1, 2, 3
- B. 1, 2, 4, 6
- C. 3, 4, 5, 6
- D. 2, 4, 5 Discuss
Correct Answer: 2, 4, 5
Explanation:
Donor impurities have five valence electrons.
- 7. 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 Discuss
Correct Answer: Both A and R are true and R is correct explanation of A
Explanation:
Heat developed depends an power loss.
- 8. When an electric field E is applied to solid and liquid insulating materials, the internal field Ei acting at the location of atom is such that
Options- A. Ei = E
- B. Ei > E
- C. Ei < E
- D. Ei may be equal to or less than E Discuss
Correct Answer: Ei > E
Explanation:
The actual field seen by an atom is larger than applied field.
- 9. The number of valence electrons in donor impurity are
Options- A. 5
- B. 4
- C. 3
- D. 1 Discuss
Correct Answer: 5
Explanation:
Donor impurity has 5 valence electrons (while silicon has 4 valence electrons).
Hence donor impurity can donate electrons.
- 10. 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 Discuss
Correct Answer: Both A and R are true and R is correct explanation of A
Explanation:
Imaginary part of ?r gives rise to absorption of energy by the material from alternating field.
Hence current does not lead the voltage by 90°.
More in Electronics and Communication Engineering:
Programming
Copyright ©CuriousTab. All rights reserved.