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This set of Electrical and Electronics Engineering Multiple Choice Questions & Answers (MCQs) focuses on Electrical And Electronics Engineering Set 1
Q1 | With the increase in the speed of a dc motor:
- both back emf as well as line current increases
- both back emf and line current falls
- back emf increases but the line current falls
- back emf falls and line current increases
Q2 | The output indicated on the name plate of any motor is always the:
- gross power
- power drawn in volt amperes
- power drawn in watts
- output power at the shaft
Q3 | The direction of rotation of dc shunt motor can be reversed by interchanging:
- the supply terminals
- the field terminals
- the armature terminals only
- either field or armature terminals
Q4 | The output power of any electrical motor is taken from the:
- armature
- field
- coupling mounted on the shaft
- motor frame
Q5 | If the back emf in a dc motor varnishes suddenly, then the motor:
- run at very high speeds
- start hunting
- burn
- come to stall
Q6 | The direction of the armature current in a dc motor is:
- the same as the generated emf
- opposite to that of generated emf
- not dependent upon the direction of the armature emf
- none of the above
Q7 | When a dc machine is connected to the dc supply main it will produce:
- emf in opposition to the applied voltage
- emf in phase with the applied voltage
- emf decreases with time
- none of the above
Q8 | The direction of rotation of a dc motor can be determined by:
- fleming\s right hand rule
- fleming\s left hand rule
- lenz\s law
- ampere\s law
Q9 | A thick wire is used in dc series motor field winding than that in dc shunt motor:
- to create more flux
- to reduce the resistance
- to carry large load current
- both (b) and ©
Q10 | An electrical train employing a dc series motor is running at the fixed speed, when a sudden slight drop in the mains voltage occurs. This would result in:
- drop in the speed and rise in the current
- rise in the speed and drop in the current
- rise in the speed and rise in the current
- drop in speed with current unaltered
Q11 | A DC shunt motor is driving a constant torque load. On inserting an additional resistance in the armature circuit, the speed of the motor will:
- remains unchanged
- increases
- decreases
- be zero
Q12 | A DC series motor is best suited for electrical traction because:
- it develops high starting torque
- it runs at very high speed
- it is cheaper in cost
- it is more rugged in construction like induction motor
Q13 | Which of the following dc motor has maximum self relieving property:
- shunt
- series
- cumulative compound
- differential compound
Q14 | When the direction of power flow in a differential compounded motor reverses, it will operate as a:
- cumulative compound generator
- differential compound generator
- series motor
- shunt motor
Q15 | A flywheel is employed with a dc compound motor to reduce the peak demand, the compound motor should be:
- level compound
- differential compound
- cumulative compound
- none of the above
Q16 | The output voltage of a DC generator is
- e = v + iara
- e = v – iara
- e = v + ia
- e = v + ra
Q17 | The material used for commutator brushes is mostly
- copper
- carbon
- mica
- cast iron
Q18 | A 4 pole DC generator rotates at 1500 rpm. How many times in a second, will the emf induced in each armature conductor changes its direction?
- 750
- 100
- 500
- 200
Q19 | Magnetic field of a DC generator is produced by what?
- permanent magnets
- electromagnets
- both option b & c
- none of the options
Q20 | In a DC generator the emf generated by the armature is maximum when
- rate of change of flux is maximum
- rate of change of flux is minimum
- induced voltage is high
- shaft rotation is high
Q21 | What is the actual arrangement of series wound generator?
- armature and field both are parallel
- armature and field both are connected
- increase the speed of shaft rotation
- armature and field both are in series with the load
Q22 | What is the effect of armature reaction?
- armature flux weakens the main field flux
- armature flux distorts the main field flux
- both option b & a
- none of the options
Q23 | In DC machine, brushes are always placed along
- magnetic neutral axis
- geometrical neutral axis
- armature axis
- load axis
Q24 | What type of connection is made in between the interpole & the field winding?
- series
- parallel
- compound
- none of the options
Q25 | In DC machine, lap winding is used in
- high current and low voltage applications
- high voltage and low current applications
- where constant speed is required
- where greater load is connected