Materials and Components problems
- 1. The v-i relation for an arc is v = 44 +
. If v = 50 V, i =
Options- A. 10 A
- B. 5 A
- C. 2 A
- D. 0.5 A Discuss
Correct Answer: 5 A
Explanation:
.
- 2. Assertion (A): Electronic polarizability increases as atoms becomes larger.
Reason (R): For rare gas, ?0(?r - 1) E = Nae, where N is number of atoms/m3 and ae is electronic polarizability of material.
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
- 3. On the basis of the type of chemical bonds, solids may be classified into
Options- A. ionic crystals
- B. ionic and valence crystals
- C. ionic crystal, valence crystals and metals
- D. ionic crystals, valence crystals, metal and vander wall crystals Discuss
Correct Answer: ionic crystals, valence crystals, metal and vander wall crystals
- 4. Piezoelectricity means the slight change in dimensions of a specimen when an electric field is applied.
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. Debye temperature of metals is
Options- A. about 10 K
- B. about 200 K
- C. about 600 K
- D. about 2 K Discuss
Correct Answer: about 200 K
- 6. A leakage capacitor can be represented by a capacitance C and resistance R in parallel C.
Options- A. True
- B. False Discuss
Correct Answer: True
- 7. A wire is carrying current I. The field intensity H at a distance r from the wire
Options- A. is directed towards wire
- B. is directed away from wire
- C. is tangential every where to a circle of radius r
- D. none of the above Discuss
Correct Answer: is tangential every where to a circle of radius r
- 8. The materials which become polarized on the application of mechanical stress are called piezoelectric.
Options- A. True
- B. False Discuss
Correct Answer: True
- 9. If t is relaxation time and tc is average time between collisions, then in an isotropic metal
Options- A. t = tc
- B. t < tc
- C. tc < t
- D. T = 0.01 te Discuss
Correct Answer: t = tc
- 10. Assertion (A): Resistivity of a perfect single crystal of a metal goes to zero as T approaches zero.
Reason (R): Scattering of electrons is due to deviations from perfect periodicity of 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
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