• #### 1.  How will you find the magnetic flux density?

• B=ϕ÷AB=\phi\div AB=ϕ÷A
• E=dϕdtE=\frac{\text{d}\phi}{\text{dt}}E=dtdϕ​
• H=MMFLH=\frac{MMF}{L}H=LMMF​
• MMM=NIMMM=NIMMM=NI
• #### 2.  What two power losses occur in a transformer when operating on no-load?

• Mechanical losses, core losses
• Frictional losses, heat losses
• Rotational losses, copper losses
• Copper losses, core losses

• True
• False
• #### 4.  Which property of a transformer is measured by the change in output voltage from no-load to full-load conditions?

• voltage ratio
• transformer efficiency
• voltage regulation
• power transfer
• #### 5.  Write the formula for finding mmf?

• B=ϕ÷AB=\phi\div AB=ϕ÷A
• E=dϕdtE=\frac{\text{d}\phi}{\text{dt}}E=dtdϕ​
• H=MMFLH=\frac{MMF}{L}H=LMMF​
• mmf=NImmf=NImmf=NI

• LL
• TT
• LE
• EI
• #### 7.  What is the danger of opening the secondary circuit of an energized current transformer?

• High voltage appears across the secondary.
• Large current flows in the primary.
• High voltage appears across the primary.
• Large current flows in the secondary.
• #### 8.  What conditions must be satisfied before connecting two transformers in parallel to share a common load?

• Same inductance, same kVA rating
• Same polarity, same phase sequence
• Same polarity resistance, same current ratio
• Same number of polarity turns, same voltage regulation
• #### 9.  What is the essential property of the oil used in transformer tanks to facilitate cooling?

• High viscosity.
• Low hydrogen content
• High carbon content
• Low viscosity
• #### 10.  In DC motor speeds above the rated speed are usually increased by changing which of the following winding current:

• field winding
• armature winding
• either field or armature winding
• none of these
• #### 11.  The direction of the induced emf in generators is found out using:

• Fleming's right hand rule
• Fleming's left hand rule
• Right hand thumb rule

• 30
• 60
• 90
• 120
• #### 13.  What type of transformer is used for interconnecting high voltage transmission systems operating at different voltage levels?

• Current transformer
• wound transformer
• Voltage transformer
• Autotransformer
• #### 14.  How can we select the thickness of fuse wire?

• based on voltage
• both
• none
• #### 15.  ____ is followed to determine the direction of coil movement for electric motors

• Fleming's left hand rule
• Fleming's right hand rule

• True
• False

• ϕ\phiϕ
• H
• B
• A
• #### 18.  During open circuit test of a transformer

• primary is supplied rated voltage
• primary is supplied full-load current
• primary is supplied current at reduced voltage
• primary is supplied rated kVA
• #### 19.  A d.c. generator whose field magnet winding is supplied from an independent external d.c. source:

• Self Excited DC generator
• Separately excited DC generator
• #### 20.  Which motor has high starting torque

• DC Series Motor
• DC Shunt Motor
• #### 21.  Why are power transformers operated in parallel?

• To increase the current rating of the supply.
• To maximize power supply flexibly.
• To improve voltage regulation.
• To reduce heat loss.
• #### 22.  What does the thumb indicate in Fleming's left hand rule

• Force
• Current
• Magnetic field
• Voltage
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