In this section, MCQs related to Electrical Machines will be covered.
- Which of the following gives material in order of decreasing values of permeability
a. Cobalt, Nickel, Aluminium, Iron
b. Permalloy, Nickel, Air, Water
c. Silver, Copper, Aluminium, Iron
d. Pure iron, Silicon iron, Aluminium Bismuth
2. In electrical machines the material preferred for pole shoes of electro-magnets is
a. Pure iron
b. Aluminium
c. Copper
d. Lead
3. The percentage of silicon in transformer stampings is usually limited to
a. 0.4%
b. 1.4%
c. 4%
d. 14%
4. Find the odd one out
a. Absorptivity
b. Emissivity
c. Refractive index
d. Dielectric strength
5. Diagmagnetic : Paramagnetic :
a. Water : Air
b. Iron : Steel
c. Permalloy : Super alloy
d. Nickel : Cobalt
6. If the permeability of a material is 0.999991 it can be classified as
a. Diamagnetic material
b. Paramagnetic material
c. Ferro-magnetic material
d. Ferrite
7. Which of the following material has the highest permeability ?
a. Nickel
b. Cobalt
c. Pure iron
d. Permalloy
8. For a simplex lap winding the commutator pitch is equal to
a. + 1
b. -+ 1
c. -1
d. +- 2
9. Which variety of copper is used for overhead conductors
a. Hard drawn copper
b. Native copper
c. Annealed copper
d. Purest form of copper
10. Anncaled copper is used in
a. low voltage cables
b. flexible wires
c. machine windings
d. all of the above
