A. conduction
B. convection
C. radiation
D. any of the above
Related Mcqs:
- The value of exciting or magnetizing current depends upon which of the following factors ?
A. Total m.m.f. required
B. The number of turns in the exciting winding
C. The way in which the winding is distributed
D. All of the above - On which of the following variables heat convected depends ?
A. Power density
B. Temperature difference between heated surface and coolant
C. Thermal resistivity, density, specific heat
D. Gravitational constant
E. All of the above - The heated parts of an electrical machine dissipate heat into their surroundings by which of the following modes of heat dissipation ?
A. Conduction
B. Convection
C. Radiation
D. All of the above - If an insulating material is operated beyond the maximum allowable temperature, its life is_____________?
A. drastically increased
B. drastically reduced
C. unaffected
D. none of the above - The time taken by the machine to attain 0.632 of its final steady temperature rise is called_____________?
A. heating time constant
B. cooling time constant
C. either A. or B.
D. none of the above - 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. - The design of electromagnets is based upon which of the following fundamental equations ?
A. Force equation
B. Magnetic circuit equation
C. Heating equation
D. Voltage equation
E. All of the above - The mcrease in heat dissipation by air blasts is due to increase in______________?
A. conduction
B. convection
E. radiation
D. any ofthe above - Hydrogen has a heat transfer co-efficient __________ times that of air?
A. 1.5
B. 2.5
C. 3.5
D. 4.5 - The heat dissipating capability of transformers of ratings higher than 30 kVA in increased by providing which of the following ?
A. Corrugations
B. Fins
C. Tubes
D. Radiator tanks
E. All of the above
