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- Question
At room temperature, the current in intrinsic semiconductor is due to
Options- A. holes
- B. electrons
- C. ions
- D. holes and electrons
- Correct Answer
- holes and electrons
ExplanationBoth electrons and holes contribute to flow of current in semiconductors.
Materials and Components problems
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- 1. 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.- 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. 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.- 4. The hysteresis phenomenon in ferromagnetic materials exists at all temperatures.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
Hysteresis phenomenon exists below ferromagnetic curie temperature.- 5. There is no hysteresis phenomenon is any dielectric material.
Options- A. True
- B. False Discuss
Correct Answer: False
Explanation:
Hysteresis phenomenon exists in dielectic materials.- 6. 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.- 7. 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.- 8. 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.- 9. 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.- 10. 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.
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