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2. In a dc generator the initial flux is produced due to
a) The saturation of the core
b) residual magnetism
c) eddy currents
d) hysteresis.
1. The flux produced by the field winding in a DC machine.
a) rotates at a synchronous speed with respect to the
stator.
b) rotates at a speed less than the synchronous speed with
respect to the stator.
c) rotates at a speed higher than the synchronous speed
with respect to the stator.
d) is stationary with respect to the stator.
3. Which of the following is the cause of production of
torque in a dc motor.
a) The resultant flux due to the field and
armature currents
a) the flux due to field currents
b) the flux due to armature current
c) none of these.
4. The emf generated in a dc motor is called back emf
because.
a) It is generated in the armature.
b) it opposes the direction of rotation of the motor.
c) it is in a direction opposite to that of the applied voltage
a) none of these.
5. Which of the following is an appropriate classification
of induction motors
a) Slip ring
b) squirrel cage
c) wound rotor
d) all of these
6. In the shell type construction of transformer which of
the following is not correct.
a) Each limb carries the primary and secondary
b) windings are sandwiched.
c) the low voltage winding is placed nearer to the core.
a) all of these.
7. The short circuit test is conducted to determine.
a) Power factor at short circuit
b) series parameters
c) efficiency
d) regulation.
8. The purpose of voltage regulation of a transformer is to
a) Maintain the voltage within the prescribed limits.
b) control the power consumption
c) control power theft
d) all of the above.
9. The root mean square of an alternating quantity is
another name for its
a) Instantaneous value
b) peak value
c) effective value
d) average value
10. If the number of poles in an ac generator is doubled and
its speed halved, the frequency of the induced emf
a) Is halved
b) remains unchanged
c) is doubled
d) is quadrapuled
11. The form factor of a rectangular wave is equal to
a) 1.0
b) 1.11
c) 1.15
d) 1.414
12. The unit of reactive power is
a) Wattt
b) VAR
c) volt ampere
d) none of the above
13. The power consumed in a pure inductive circuit
a) Zero
b) VmIm/2
c) VI
d) IL
14. Reactive power in a circuit signifies
a) Energy consumed by the magnetic/electric field
b) Energy consumed by the resistance of inductance
and capacitance
c) Energy exchanged between the magnetic/electric field
and the source
d) Energy consumed by the resistance in the circuit.
15. In a series RLC circuit, resonance occurs at
a) L=C
b) R=C
c) R=L
d) Xl=Xc
16. Super position theorem can be employed to
a) Voltages only
b) currents only
c) power only
d) all of the above
17. Thevenin,s theorem can be applied to networks
containing
a) Passive elements only
b) active elements
c) linear elements only
d) all of the above
18. Which of the following theorems helps in simplifying
computations when the load across a circuit is varying
a) Superposition
b) Nortons
c) Thevenins
d) Maximum power transfer
19. One farad is equal to
a) 1Ω
b) 1V/C
c) 1C/V
d) none of the above
20. The unit of resistivity is
a) Ω
b) Ω/m
c) Ω/m2
d) Ωm