Materials and Components problems
- 1. As the temperature of a pure silicon specimen is increased
Options- A. the number of free electrons increases
- B. the number of holes decreases
- C. the number of holes increases
- D. the number of free electrons and holes increases Discuss
Correct Answer: the number of free electrons and holes increases
- 2. When a material becomes a superconductor, its resistivity becomes
Options- A. very small
- B. zero
- C. about 10% of normal value
- D. about 20% of normal value Discuss
Correct Answer: zero
Explanation:
A superconductor has zero resistance.
- 3. In metals the thermal conductivity K and electrical conductivity ? are related as (K/?T) = L, L is known as
Options- A. Lattice constant
- B. Lorentz number
- C. Lanevin function
- D. Larmor number Discuss
Correct Answer: Lorentz number
- 4. In metals, the average drift velocity of electron per unit field is called mobility.
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. Silicon and germanium atoms combine orderly into array of atoms located in repetitive geometric pattern. This pattern is called
Options- A. crystal
- B. covalent bond
- C. molecule
- D. valence bond Discuss
Correct Answer: crystal
- 6. Dielectric constant of transformer oil is about
Options- A. 1
- B. 4
- C. 10
- D. 20 Discuss
Correct Answer: 4
- 7. In carbon resistor colour code, the third band is red. It indicates
Options- A. two zeros
- B. three zeros
- C. multiplier is 0.01
- D. multiplier is 0.1 Discuss
Correct Answer: two zeros
- 8. Assertion (A): In many materials, dielectric polarization causes mechanical distortion.
Reason (R): If dielectric polarization causes mechanical distortion then mechanical distortion must cause dielectric polarization.
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: A is true but R is false
- 9. Consider the following statement
If an electric field is applied to an n type semiconductor bar, the electrons and holes move in opposite directions due to their opposite charges. The net currents is- both due to electrons and holes with electrons as majority carriers
- sum of hole and electron currents
- difference between electron and hole currents.
Options- A. 1 only
- B. 1 and 2
- C. 2 only
- D. 3 only Discuss
Correct Answer: 1 and 2
Explanation:
The net current is sum of currents due to holes and electrons.
In n type materials, electrons are majority carriers.
- 10. Assertion (A): ?r can be determined experimentally by measuring the capacitance of a parallel plate capacitor with and without the dielectric.
Reason (R): Capacitance of a parallel plate capacitor =
.
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
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