Materials and Components problems
- 1. The most important set of specifications of transformer oil include
Options- A. dielectric strength and viscosity
- B. dielectric strength and flash point
- C. viscosity and flash point
- D. flash point and viscosity Discuss
Correct Answer: dielectric strength and viscosity
- 2. If ?p is permanent dipole moment and T is absolute temperature, the orientation polarization of polyatomic gases is
Options- A. proportional to ?p2T
- B. proportional to
- C. proportional to ?p T
- D. proportional to
Discuss
Correct Answer: proportional to
Explanation:
Orientation polarization = N?p2E/3 kT.
- 3. We can know the arrangement of atom in a material by studying electron diffraction pattern.
Options- A. True
- B. False Discuss
Correct Answer: True
- 4. Schrodinger wave equation is partial differential equation.
Options- A. True
- B. False Discuss
Correct Answer: True
- 5. Assertion (A): If an atom of polarizability a is placed in homogeneous field E, the energy stored is 0.5 aE2.
Reason (R): Capacitance of an isolated conducting sphere R in vacuum is 4 p?0 R farads.
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
- 6. The charge per proton is
Options- A. 1.6 x 10-19 C
- B. 2.6 x 10-19 C
- C. 0.6 x 10-19 C
- D. 1.6 x 10-13 C Discuss
Correct Answer: 1.6 x 10-19 C
Explanation:
Because charge on proton is positive but numerically equal to that on electron.
- 7. The capacitance of a capacitor is not affected by
Options- A. area of plates
- B. thickness of plates
- C. ?r
- D. distance between plates Discuss
Correct Answer: thickness of plates
Explanation:
Capacitance depends on area, distance and ?r but not on thickness of plates.
- 8. Hall effect is observed in a specimen (metal or semi- conductor) when it is carrying current and is placed in a magnetic field. The resultant electric field inside the specimen is
Options- A. normal to both current and magnetic field
- B. in the same direction as current
- C. in a direction anti parallel to magnetic field
- D. none of the above Discuss
Correct Answer: normal to both current and magnetic field
- 9. With increase in temperature, the electrical conductivity would
Options- A. increase in metals as well as in intrinsic semiconductor
- B. increase in metals but decrease in intrinsic semiconductor
- C. decrease in metals but increase in intrinsic semiconductor
- D. decrease in metals as well as in intrinsic semiconductor Discuss
Correct Answer: decrease in metals but increase in intrinsic semiconductor
Explanation:
Increase in temperature causes resistivity of metals to increase and resistivity of intrinsic semiconductors to decrease.
Conductivity is reciprocal of resistivity.
- 10. Yettrium-iron garnet (Y2Fe5O12) is a soft magnetic material suitable for applications involving
Options- A. dc
- B. 50 Hz ac
- C. ac of a few K Hz
- D. ac of a few hundred MHz Discuss
Correct Answer: dc
Explanation:
Yettrium iron garnet has very low eddy current loss. Hence it is used at frequencies in MHz range.
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