Hi friends, this is post about objectives of electrical engineering with emphasis on dc motor check out and comment...
1) When is the mechanical power developed by a dc motor maximum?
A) Back emf is equal to applied voltage
B) Back emf is equal to zero
C) Back emf is equal to half the applied voltage
D) None of the above
Ans:C
2) The output power of any electrical motor is taken from the
A) armature
B) field
C) coupling mounted on the shaft
D) motor frame
Ans:C
3) The direction of rotation of a dc series motor can be reversed
A) by interchanging supply terminals
B) by interchanging field terminals
C) either by interchanging supply terminals or by interchanging field terminals
D) by interchanging supply terminals as well as field terminals
Ans:B
4) A dc motor having full load speed of 750 rpm and speed regulation of 10% will have no load speed of
A) 825 rpm
B) 675 rpm
C) 800 rpm
D) 700 rpm
Ans:A
5) The current drawn by a 120 V dc motor with back emf of 110 V and armature resistance of 0.4 Ω is
A) 4 A
B) 25 A
C) 275 A
D) 300 A
Ans:B
6) A 220 V dc machine has an armature resistance of 1Ω. If the full load current is 20 A, the difference of induced voltage, when the machine is running as a motor and generator is
A) 20 V
B) 0 V
C) 40 V
D) 60 V
Ans:C
7) In a dc compound motor the field regulator is provided to
A) control the flux
B) limit the armature current
C) demagnetize field partially
D) none of the above
Ans:A
8) The armature shaft must be able to withstand
A) any unbalanced magnetic pull on the armature core
B) twisting strains due to transmission of torque
C) bending moment due to weight of the armature and commutator
D) all of the above
Ans:D
9) A thicker wire is used in dc series motor field winding than that in a dc shunt motor
A) to create more flux
B) to reduce resistance
C) to carry large load current
D) both (b) and (C)
Ans:D
10) The direction of rotation of a dc motor can be determined by
A) Fleming's right hand rule
B) Fleming's left hand rule
C) lenz's law
D) Ampere law
Ans:B
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1) When is the mechanical power developed by a dc motor maximum?
A) Back emf is equal to applied voltage
B) Back emf is equal to zero
C) Back emf is equal to half the applied voltage
D) None of the above
Ans:C
2) The output power of any electrical motor is taken from the
A) armature
B) field
C) coupling mounted on the shaft
D) motor frame
Ans:C
3) The direction of rotation of a dc series motor can be reversed
A) by interchanging supply terminals
B) by interchanging field terminals
C) either by interchanging supply terminals or by interchanging field terminals
D) by interchanging supply terminals as well as field terminals
Ans:B
4) A dc motor having full load speed of 750 rpm and speed regulation of 10% will have no load speed of
A) 825 rpm
B) 675 rpm
C) 800 rpm
D) 700 rpm
Ans:A
5) The current drawn by a 120 V dc motor with back emf of 110 V and armature resistance of 0.4 Ω is
A) 4 A
B) 25 A
C) 275 A
D) 300 A
Ans:B
6) A 220 V dc machine has an armature resistance of 1Ω. If the full load current is 20 A, the difference of induced voltage, when the machine is running as a motor and generator is
A) 20 V
B) 0 V
C) 40 V
D) 60 V
Ans:C
7) In a dc compound motor the field regulator is provided to
A) control the flux
B) limit the armature current
C) demagnetize field partially
D) none of the above
Ans:A
8) The armature shaft must be able to withstand
A) any unbalanced magnetic pull on the armature core
B) twisting strains due to transmission of torque
C) bending moment due to weight of the armature and commutator
D) all of the above
Ans:D
9) A thicker wire is used in dc series motor field winding than that in a dc shunt motor
A) to create more flux
B) to reduce resistance
C) to carry large load current
D) both (b) and (C)
Ans:D
10) The direction of rotation of a dc motor can be determined by
A) Fleming's right hand rule
B) Fleming's left hand rule
C) lenz's law
D) Ampere law
Ans:B
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