1. What is the unit of reluctance in magnetic materials?
a) Henry/m
b) Weber/m2
c) Ampere-turns/Weber
d) Ampere-turns/m
Explanation: Henry/m deals with the unit of permeability. Weber/m2 deals with the unit of magnetic field. Reluctance is the opposite of permeance.
2. How many classifications of magnetic materials are present?
a) 3
b) 4
c) 5
d) 6
Explanation: There are basically 4 properties in magnetic materials and 5 classifications. They are diamagnetic, paramagnetic, ferromagnetic, antiferromagnetic, ferrimagnetic.
3. What is the property of ferromagnetic materials?
a) Negative magnetization
b) Magnetization slightly less than 1
c) Magnetization slightly greater than 1
d) Magnetization very much higher than 1
Explanation: Negative magnetization denotes the property of Diamagnetic materials. Magnetization slightly greater than 1 denotes the property of Paramagnetic materials. Ferromagnetic materials have magnetization in the range of 1000+.
4. What is the example of diamagnetic materials?
a) Quartz
b) Pyrite
c) Montmorillonite
d) Biotite
Explanation: The other 3 materials are paramagnetic in nature, which means magnetization is slightly above 1. Quartz is a diamagnetic material in which the magnetization is negative.
5. Which of the following flow is best suited for space shuttle?
a) continuum flow
b) free molecular flow
c) turbulent flow
d) laminar flow
Explanation: Hematite denotes the example of antiferromagnetic materials. Nickel denotes an example of ferromagnetic materials. Biotite denotes the example of paramagnetic materials.
6. How many number of insulation classes are present with respect to electrical equipment?
a) 5
b) 6
c) 7
d) 8
Explanation: There are 7 classes of insulation with respect to electrical equipment. They are Class Y, Class A, Class E, Class B, Class F, Class H, Class C.
7. How many classes have their temperatures above 100°C?
a) 5
b) 6
c) 7
d) 8
Explanation: There are 7 insulation classes present in relation with temperature. Of the 7 classes, there are 6 classes whose temperatures are greater than 100°C. Class Y is the only class having temperature less than 100.
8. How many classes have their temperatures above 150°C?
a) 2
b) 3
c) 4
d) 5
Explanation: Of 7 classes of insulation, there are 3 classes whose temperatures are above 150°C. They are classes F, H, C of insulation
9. Which class has the lowest and the highest temperature?
a) Class Y, Class C
b) Class Y, Class H
c) Class H, Class C
d) Class B, Class H
Explanation: Class Y belongs to the lowest insulation class of having temperature of about 90°C. Class C is the highest insulation class of having temperature above 180°C.
10. Class A has higher temperature than Class E.
a) True
b) False
Explanation: Class E has a higher temperature than that of Class A. The temperature of Class A is 105°C and the temperature of Class E is 120°C