1.Fleming's Left hand rule is applicable to:
a) DC generatorb) DC motor
c) Transformer
d) Alternator
2. A conductor is rotating within a magnetic field. At which position do the peak voltage occur:
a) At the right angles to the axis of magnetic fieldb) Along the axis of magnetic field
c) At 45 deg angles to the axis of magnetic filed
d) None of the above
3. Reluctance torque in rotating machines is present when:
a) Air gap is not uniformb) Reluctance seen by rotor mmf varies
c) Reluctance seen by stator mmf varies
d) Reluctance seen by working mmf varies
4.The DC generator is considered as:
a) Rotating amplifierb) rectifier
c) voltage regulator
d) none of the above
5.The yoke in the dc machine is laminated
a) Trueb) False
6.Poles of the dc machine is laminated:
a) To reduce pulsating lossb) Reduce Armature Reaction
c) To improve commutation
d) Reduce the weight of the poles
7.The armature of the dc machine is made of silicon steel of:
a) High permeability and good mechanical strengthb) Low permeability and good mechanical strength
c) Only has the property of good mechanical strength
d) None of the above
8.The ventilating ducts in dc machines are generally
a) radialb) longitudinal
c) both radial and longitudinal
d) none of the above
9.The armature of the dc machines are laminated to reduce:
a) Eddy current lossb) Hysteresis loss
c) copper loss
d) field flux loss
10.Eddy currents are induced in the pole shoes of dc machine due to:
a) Pulsating magnetic lossb) Oscillating magnetic loss
c) Relative motion between field and armature
d) both a and c
