DC Generators Exam Questions with Correct
Answers (VerifiedAnswers) Plus Rationales
2026 Q&A Instant Download PDF
1. A DC generator operates primarily on which principle?
A. Ohm's law
B. Coulomb's law
C. Faraday's law of electromagnetic induction
D. Kirchhoff's voltage law
Rationale: A DC generator converts mechanical energy into
electrical energy through electromagnetic induction. When
armature conductors rotate through the magnetic field, they cut
magnetic flux and an electromotive force is induced in them.
Faraday's law establishes the fundamental relationship between
changing flux linkage and induced EMF. The commutator then
converts the internally generated alternating EMF into a
unidirectional terminal output.
2. Which component of a DC generator converts the internally
generated alternating current into a unidirectional external
current?
,A. Slip rings
B. Commutator
C. Pole shoe
D. Field winding
Rationale: The EMF induced in individual armature coils is
alternating because the conductors successively move under
north and south poles. The split commutator reverses the coil
connections at appropriate intervals, so the current delivered to
the external circuit remains unidirectional. This is the key
difference between a DC generator using a commutator and an
AC generator using slip rings.
3. Which winding is connected in parallel with the armature in
a DC shunt generator?
A. Series field winding
B. Shunt field winding
C. Compensating winding
D. Interpole winding
Rationale: The shunt field winding is made of many turns of
relatively fine wire and has comparatively high resistance. It is
connected across the armature terminals so that it receives
approximately the generator terminal voltage. Because its
current is relatively small compared with the load current, a
shunt generator can provide reasonably stable excitation.
,4. A DC series generator has its series field winding connected:
A. In parallel with the armature
B. In series with the armature and load
C. Across the shunt field only
D. Across the commutator segments
Rationale: A series field winding carries the same current that
flows through the armature and external load. Consequently, it
consists of relatively few turns of thick conductor capable of
carrying substantial current. Its magnetic flux therefore changes
significantly with load current, which gives the series generator
its characteristic rising voltage behavior over part of its
operating range.
5. Which type of DC generator contains both series and shunt
field windings?
A. Separately excited generator
B. Shunt generator
C. Series generator
D. Compound generator
Rationale: A compound generator combines the characteristics
of a shunt generator and a series generator by incorporating
both field windings. The series field can either aid or oppose the
, shunt-field flux. When the fields aid each other, the generator is
cumulatively compounded; when they oppose each other, it is
differentially compounded.
6. In a cumulatively compounded generator, the series-field
flux:
A. Opposes the shunt-field flux
B. Aids the shunt-field flux
C. Is always zero
D. Is independent of load current
Rationale: In cumulative compounding, the magnetic flux
produced by the series winding acts in the same direction as the
shunt-field flux. As load current increases, series-field flux
therefore tends to increase the total flux and generated EMF.
This arrangement can be designed to compensate for internal
voltage drops and produce improved voltage regulation.
7. In a differentially compounded generator, the series-field
flux:
A. Aids the shunt field
B. Has no effect on the main field
C. Opposes the shunt-field flux
D. Is always greater than the shunt flux
Answers (VerifiedAnswers) Plus Rationales
2026 Q&A Instant Download PDF
1. A DC generator operates primarily on which principle?
A. Ohm's law
B. Coulomb's law
C. Faraday's law of electromagnetic induction
D. Kirchhoff's voltage law
Rationale: A DC generator converts mechanical energy into
electrical energy through electromagnetic induction. When
armature conductors rotate through the magnetic field, they cut
magnetic flux and an electromotive force is induced in them.
Faraday's law establishes the fundamental relationship between
changing flux linkage and induced EMF. The commutator then
converts the internally generated alternating EMF into a
unidirectional terminal output.
2. Which component of a DC generator converts the internally
generated alternating current into a unidirectional external
current?
,A. Slip rings
B. Commutator
C. Pole shoe
D. Field winding
Rationale: The EMF induced in individual armature coils is
alternating because the conductors successively move under
north and south poles. The split commutator reverses the coil
connections at appropriate intervals, so the current delivered to
the external circuit remains unidirectional. This is the key
difference between a DC generator using a commutator and an
AC generator using slip rings.
3. Which winding is connected in parallel with the armature in
a DC shunt generator?
A. Series field winding
B. Shunt field winding
C. Compensating winding
D. Interpole winding
Rationale: The shunt field winding is made of many turns of
relatively fine wire and has comparatively high resistance. It is
connected across the armature terminals so that it receives
approximately the generator terminal voltage. Because its
current is relatively small compared with the load current, a
shunt generator can provide reasonably stable excitation.
,4. A DC series generator has its series field winding connected:
A. In parallel with the armature
B. In series with the armature and load
C. Across the shunt field only
D. Across the commutator segments
Rationale: A series field winding carries the same current that
flows through the armature and external load. Consequently, it
consists of relatively few turns of thick conductor capable of
carrying substantial current. Its magnetic flux therefore changes
significantly with load current, which gives the series generator
its characteristic rising voltage behavior over part of its
operating range.
5. Which type of DC generator contains both series and shunt
field windings?
A. Separately excited generator
B. Shunt generator
C. Series generator
D. Compound generator
Rationale: A compound generator combines the characteristics
of a shunt generator and a series generator by incorporating
both field windings. The series field can either aid or oppose the
, shunt-field flux. When the fields aid each other, the generator is
cumulatively compounded; when they oppose each other, it is
differentially compounded.
6. In a cumulatively compounded generator, the series-field
flux:
A. Opposes the shunt-field flux
B. Aids the shunt-field flux
C. Is always zero
D. Is independent of load current
Rationale: In cumulative compounding, the magnetic flux
produced by the series winding acts in the same direction as the
shunt-field flux. As load current increases, series-field flux
therefore tends to increase the total flux and generated EMF.
This arrangement can be designed to compensate for internal
voltage drops and produce improved voltage regulation.
7. In a differentially compounded generator, the series-field
flux:
A. Aids the shunt field
B. Has no effect on the main field
C. Opposes the shunt-field flux
D. Is always greater than the shunt flux
