Objectives on Insulating materials and their properties and applications in part 4
This sets of mcq's contains questions on insulating materials, properties, their applications, Ceramics, Mica, Asbestos, Varnish in part 4..
Click here to read part 1 of insulatng materials..
Click here to read part 2 of insulatng materials..
Click here to read part 3 of insulatng materials..
SET 1 of Insulating materials and their properties and applications mcq's
1. Material that does not allow current under normal conditions is
A. an insulator
B. conductor
C. semiconductor
D. superconductor
Answer A
Marks 1
2. Glass is ……….material.
A. tough
B. brittle
C. ductile
D. none of these
Answer B
Marks 1
3. Plastic is……….
A. good conductor of electricity
B. good conductor of heat
C. bad conductor of electricity
D. none of these
Answer C
Marks 1
4. ……is employed for cable insulation.
A. Rubber
B. Polystyrene
C. PVC
D. Phenol formaldehyde
Answer C
Marks 1
5. Which one of the following materials has the maximum dielectric strength?
A. soft rubber
B. glass
C. porcelain
D. polystyrene
Answer A
Marks 1
6. An insulating material starts conducting when the
A. temperature is raised to very high level
B. voltage applied exceeds the breakdown voltage
C. either (A) or (B)
D. none of these
Answer B
Marks 1
7. Surface resistivity of insulating material is reduced in ……….atmosphere.
A. humid
B. smoky & dirty
C. both (A) & (B)
D. none of above
Answer C
Marks 1
8. An exposure of insulating material to any contamination, causes increase in …..
A. dielectric loss
B. dielectric constant
C. dielectric strength
D. insulation resistance
Answer A
Marks 1
9. The most important qualities which a good insulating material should posses are
A. large insulation resistance& high dielectric strength
B. less thermal expansion & low dielectric loss
C. good heat conductivity, high mechanical strength & high melting point
D. both (A) & (B)
Answer D
Marks 1
10. Electro-mechanical breakdown of solid insulating materials occurs, due to
A. magnetic hum
B. vibrations
C. mechanical stresses produced by the electrical field
D. electrical stresses produced by the voltage fluctuations
Answer C
Marks 1
SET 2 of Insulating materials and their properties and applications mcq's
11. The materials which are used for storing electrical energy are classified as ……… materials.
A. insulating
B. dielectrics
C. superconducting
D. semiconducting
Answer B
Marks 1
12. Dielectrics have ……..free electrons.
A. a few
B. many
C. no
D. none of these
Answer C
Marks 1
13. Dielectric strength of gaseous dielectrics are depend on
A. polarity of electrodes
B. pressure & uniformly applied electric field
C. frequency of applied
D. all of above
Answer D
Marks 1
14. The dielectric breakdown strength of material depends on its …
A. composition
B. thickness
C. moisture content
D. all of the above
Answer D
Marks 1
15. Which of the following material is used for cable insulation ?
A. phenol formaldehyde
B. polytetra fluroethylene
C. polyvinyl chloride
D. acrylontrile butadiene styrene
Answer C
Marks 1
16. Bakelite is
A. a semi-conductor
B. incombustible
C. low resistance conductor
D. highly inflammable
Answer B
Marks 1
17. Class Y :: 90 oC , Class C :: ?
A. 110 oC
B. 130 oC
C. 225 oC
D. 95 oC
Answer C
Marks 1
18. While selecting a gas, for circuit breaker, the property of gas that should be considered is
A. high dielectric strength
B. non-inflammability
C. good arc quenching property
D. all of the above
Answer D
Marks 1
19. In a Townsend discharge, the current increases gradually as a function of the __________
A. frequency
B. charge on electron
C. applied voltage
D. work function
Answer C
Marks 1
20. In addition to insulating properties, SF6 possesses excellent __________ properties.
A. magnetic
B. arc quenching
C. electric
D. conducting
Answer B
Marks 1
SET 3 of Insulating materials and their properties and applications mcq's
21. Disruptive discharge voltage is the voltage which produces the loss of ______strength of insulation.
A. dielectric
B. magnetic
C. electric
D. mechanical
Answer A
Marks 1
22. The breakdown of insulation of the cable can be avoided economically by the use of
A. inter-sheaths
B. insulating materials with different dielectric constants
C. both (A) and (B)
D. none of the above
Answer C
Marks 1
23. Which of the following factors do affect the resistivity of metal ?
A. Age hardening
B. Alloying
C. Temperature
D. All of the above
Answer D
Marks 1
24. Which of the following insulating materials can tolerate maximum temperature?
A. mica
B. ceramics
C. glass
D. All of the above
Answer D
Marks 1
25. While selecting a gas for circuit breaker, the property of gas that should be considered is
A. high dielectric strength
B. non-inflammability
C. all of the above
D. none of the above
Answer C
Marks 1
26. Electrical Machine's slot liners:: cotton tapes , Capacitor body :: ?
A. plastic
B. wood
C. ceramic
D. rubber
Answer C
Marks 1
Click here to read part 1 of insulatng materials..
Click here to read part 2 of insulatng materials..
Click here to read part 3 of insulatng materials..
