1. The external characteristic is plotted between ____________
a) terminal voltage vs armature current at constant excitation
b) terminal voltage vs field current at constant armature current
c) induced armature emf vs armature current at constant excitation
d) none of the mentioned
Explanation: The external characteristic is plotted between terminal voltage and armature current at fixed excitation.
2. A student forgot to mark the x-y axes in his experiments but he just noted down the cause and the effect for each. How will he conclude about the armature characteristic out of the all plotted graphs?
a) By marking graph for constant terminal voltage
b) By marking graph for constant field current
c) By marking graph for constant armature current
d) By marking graph for constant speed
Explanation: Armature characteristic is observed at constant terminal voltage for emf vs armature current.
3. Armature characteristic is also known as _________
a) regulation characteristic
b) magnetization characteristic
c) external characteristic
d) load characteristic
Explanation: Armature characteristic is also known as regulation characteristic. It is so called due to the fact that the difference in the terminal voltage helps to determine the voltage deviation.
4. The air gap line represents _________
a) magnetic behaviour of the air gap of the dc machine
b) magnetic behaviour of the air gap of the induction machine
c) magnetic behaviour of the iron core
d) all of the mentioned
Explanation: Air gap line in the magnetization curve represents the ideal nature of the machine considering no saturation for the dc machine.
5. The voltage drop in terminal voltage from no-load to full load in a shunt generator can be compenated using _________
a) aiding series field
b) long-shunt, diferential field
c) aiding shunt field
d) any of the measures
Explanation: By aiding the series field the armature reaction drop can be compensated.
6. Why is armature of a dc machine made of silicon steel stampings?
a) To reduce hysteresis loss
b) To reduce eddy current loss
c) For the ease with which slots can be created
d) To achieve high permeability
Explanation: The silicon steel has very high permeability and makes the flux past consistent. Thereby making lesser losses.
7. What losses occur in the teeth of dc generator?
a) To reduce hysteresis loss
b) To reduce eddy current loss
c) To reduce eddy current as well as hysteresis losses
d) To achieve high permeability
Explanation: Teeth of the machine has both eddy current losses as well as hysteresis losses.
8. For a 220-V level compound generator the terminal voltage at the half load is?
a) more than 220-V
b) same as no-load voltage
c) more than no-load voltage
d) lesser than no-load voltage
Explanation: In a level compound dc generator the terminal voltage remains same as no load voltage at all the loading.
9. The rotating amplifiers are widely used in ____________
a) small amplified outputs
b) large amplified outputs
c) amplified outputs
d) large power gain outputs
Explanation: The rotating amplifiers are applicable in feedback systems giving large amplified outputs.
10. The quantity which make rotating amplifier applicable in large power levels is/are _________
a) high power gain and favourable transient conditions
b) favourable transient conditions
c) high power gain
d) favourable steady state conditions
Explanation: The rotating amplifiers have stable transient conditions, which makes them favourable to use in high power sectors.