Practice Test: Question Set - 09
1. The length of air gap to be provided in __________ is primarily determined by power factor consideration.
- (A) D.C. series motor
- (B) D.C. shunt motor
- (C) Induction motor
- (D) Synchronous motor
2. The design of electromagnets is based upon which of the following fundamental equations?
- (A) Force equation
- (B) Magnetic circuit equation
- (C) Heating equation
- (D) All of the above
3. The laminations of the armature of a D.C. machine are usually ________ thick.
- (A) 0.1 to 0.2 mm
- (B) 0.2 to 0.3 mm
- (C) 0.3 to 0.4 mm
- (D) 0.4 to 0.5 mm
4. In a D.C. machine the number of brush arms is _____ the number of poles.
- (A) Less than
- (B) Equal to
- (C) Greater than
- (D) None of the above
5. Which of the following materials is used in the manufacture of resistance grids to be used in the starters of large motors?
- (A) Copper
- (B) Aluminium
- (C) Steel
- (D) Cast-iron
6. In ________ machines, the size of the shaft is decided by the critical speed which depends on the deflection of the shaft.
- (A) Small
- (B) Medium
- (C) Large
- (D) Any of the above
7. The change in flux linkages can be caused in which of the following ways?
- (A) The flux is constant with respect to time
and is stationary and the coil moves through it
- (B) The coil is stationary with respect to flux and the
flux varies in magnitude with respect to time
- (C) Both the changes mentioned above occur
together, i.e., the coil moves through a time varying field
- (D) All of the above
8. Hot rolled sheets have _________ value of permeability
- (A) Zero
- (B) Low
- (C) High
- (D) None of the above
9. On which of the following variables heat convection depends?
- (A) Power density
- (B) Temperature difference between heated surface and
coolant
- (C) Thermal resistivity, density, specific heat, Gravitational
constant
- (D) All of the above
10. The resistivity of water should not be less than
- (A) 10 Q m
- (B) 100 Q m
- (C) 1000 Q m
- (D) 2000 Q m
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