Objectives on Insulating materials and their properties and applications in part 3
This sets of mcq's contains questions on insulating materials, properties, their applications, Ceramics, Mica, Asbestos, Varnish in part 3..
Click here to read part 1 of insulatng materials..
Click here to read part 2 of insulatng materials..
SET 1 of Insulating materials and their properties and applications mcq's
1. Asbestos cloth is used for---
A. sleeves of heating devices
B. for equipment working at high temperature
C. in panels for switchgear and arcing
D. insulation for traction motors and auto mobile starting motor
Answer D
Marks 1
2. ----------------- class of ceramics is used in carrier body covers for ICs and resistors, heat shields etc.
A. Alumina
B. Steatite
C. Porcelain
D. Titanite
Answer A
Marks 1
3. ---------------- class of ceramics is used for high frequency applications.
A . Alumina
B. Steatite
C. Porcelain
D. Titanite
Answer B
Marks 1
4. Asbestos has --------- .
A. fibrous structure
B. crystalline structure
C. grain oriented crystalline structure
D. No none of the above
Answer A
Marks 1
5. An Insulator is defined as a material having resistivity- roughly in the range -------- .
A. 103 to 1017 ohm-m
B. 107 to 1010ohm-m
C. 1013 to 1015 ohm-m
D. 1015 to 1017 ohm-m
Answer D
Marks 1
6. Dielectric strength in case of mica can be expected to be more than
A. 500 kV/mm
B. 1500 kV/mm
C. 2500 kV/mm
D. 3500 kV/mm
Answer A
Marks 1
7. Which variety of mica is hard and brittle?
A. Muscovite
B. Phlogopite
C. Fibiolite
D. Micanite
Answer A
Marks 1
8. Which one of the following is NOT true for Sulphur Hexafluoride gas?
A. It is electronegative in nature.
B. It has high dielectric strength.
C. It is non-toxic.
D. It is highly inflammable.
Answer D
Marks 1
9. Insulation used in commutator is
A. wood
B. PVC
C. mica
D. glass
Answer C
Marks 1
10. The Insulators need ________ energy to shift electrons from valance band to conduction band in comparison to conductors, superconductors and semiconductors.
A. maximum
B. minimum
C. zero
D. negligible
Answer A
Marks 1
SET 2 of Insulating materials and their properties and applications mcq's
11. Calculate the breakdown strength of air, if gap between two spheres is 10 mm and the breakdown voltage is 20 kV(R.M.S. Value).
A. 10 kV /mm
B. 2 kV /mm
C. 30 kV /mm
D. 1.5 kV /mm
Answer B
Marks 1
12.An exposure of insulating material to moisture, causes increase in
A. dielectric loss
B. dielectric constant
C. dielectric strength
D. insulation resistance
Answer A
Marks 1
13.The electric breakdown strength of an insulating material depends on
A. composition of material
B. moisture content
C. thickness of material
D. all of the above
Answer D
Marks 1
14. Which of the following insulating materials has the least affinity for moisture?
A. Cotton
B. Paper
C. Asbestos
D. Mica
Answer D
Marks 1
15. The temperature coefficient of resistance of an insulator is
A. positive and independent of temperature
B. negative and independent of temperature
C. negative and dependent of temperature
D. positive and dependent of temperature
Answer C
Marks 1
16. Line insulators are made of
A. Porcelain
B. Mica
C. Marble
D. PVC
Answer A
Marks 1
17.In electrical machines, varnish is mainly used in
A. impregnation
B. coating
C. adhesion
D. all of these
Answer D
Marks 1
18.Sometimes varnish is coated on hard porous insulating materials. This is done to improve -------------------- properties.
A. magnetic
B. ionic
C. electronic
D. none of these
Answer D
Marks 1
19.Spark plug makes use of ________ for insulation.
A. Mica
B. Porcelain
C. Asbestos
D. Glass
Answer B
Marks 1
20.Which of the following is a ceramic material?
A. MgO
B. Leather
C. Invar
D. Nylon
Answer A
Marks 1
SET 3 of Insulating materials and their properties and applications mcq's
21. Which material can be used at temperatures above 100°C?
A. Paraffin wax.
B. Rubber
C. Teflon
D. Polythene
Answer C
Marks 1
22.Winding conductors of an electrical power transformer are mainly insulated by
A. Cotton Insulation.
B. Rubber Insulation.
C. Paper Insulation.
D. Wooden Insulation
Answer C
Marks 1
23. The insulator should have
A. low insulation resistance
B. high relative permittivity
C. weak mechanical strength
D. low relative permittivity
Answer B
Marks 1
24. Insulators are required to withstand
A. mechanical stress
B. electrical stress
C. both mechanical stress and electrical stress
D. none of above
Answer B
Marks 1
25. An ideal liquid insulating material should have low
A. heat conductivity
B. dielectric strength
C. mechanical strength
D. volatility
Answer D
Marks 1
26. The dielectric strength of transformer oil should not be less than
A. 10kV
B. 20 kV
C. 30 kV
D. 50 kV
Answer C
Marks 1
27. The disadvantage with paper as an insulating material is
A It is hygroscopic
B It has high capacitance
C It is an organic material
D None of these
Answer A
Marks 1
28. The insulating material for a cable should have ______
A. low cost
B. high dielectric strength
C. high mechanical strength
D. all of the above
Answer D
Marks 1
29.The thickness of the layer of insulation on the conductor, in cables, depends upon
A. reactive power
B. power factor
C. voltage
D. current carrying capacity
Answer C
Marks 1
30.PVC stands for _______.
A. polyvinyl chloride
B. post varnish conductor
C. pressed and varnished cloth
D. positive voltage conductor
Answer A
Marks 1
Click here to read part 1 of insulatng materials..
Click here to read part 2 of insulatng materials..
