All practical electromechanical energy conversion devices make use of the magnetic field rather than the electric field as the coupling medium. This is because ________

electric field systems present insulation difficulties

electric field systems have more dielectric loss than the magnetic loss, for the same power rating of the machine

in electric field systems, for normal electric field strength, the stored energy density is high

in magnetic field systems, for normal magnetic flux density, the stored energy density is high

Electromagnetic torque in rotating electrical machinery is present when ________

stator winding alone carries current

rotor winding alone carries current

both stator and rotor windings carry current

Singly and doubly excited magnetic systems applications are respectively ________

synchronous motors and moving iron instruments

DC shunt machines and solenoids

reluctance motors and synchronous motors

In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _____________

both stator and rotor currents are acting

any of the stator or rotor currents acting alone

In a doubly excited magnetic systems, the magnetic torques and forces act in such a direction as to tend to ___________

decrease the field energy at constant currents

decrease the field co-energy at constant currents

increase the field energy at constant currents

Explore topic-wise MCQs in Electrical Machines.

This section includes 5 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Machines knowledge and support exam preparation. Choose a topic below to get started.

1.	All practical electromechanical energy conversion devices make use of the magnetic field rather than the electric field as the coupling medium. This is because ________
A.	electric field systems present insulation difficulties
B.	electric field systems have more dielectric loss than the magnetic loss, for the same power rating of the machine
C.	in electric field systems, for normal electric field strength, the stored energy density is high
D.	in magnetic field systems, for normal magnetic flux density, the stored energy density is high
Answer» E.

Discussion

2.	Electromagnetic torque in rotating electrical machinery is present when ________
A.	stator winding alone carries current
B.	rotor winding alone carries current
C.	air gap is uniform
D.	both stator and rotor windings carry current
Answer» E.

Discussion

3.	Singly and doubly excited magnetic systems applications are respectively ________
A.	loud speakers and tachometers
B.	synchronous motors and moving iron instruments
C.	DC shunt machines and solenoids
D.	reluctance motors and synchronous motors
Answer» E.

Discussion

4.	In a doubly excited magnetic system of salient pole type stator and rotor, the reluctance torque is present only when _____________
A.	both stator and rotor currents are acting
B.	stator current is acting alone
C.	rotor current is acting alone
D.	any of the stator or rotor currents acting alone
Answer» E.

Discussion

5.	In a doubly excited magnetic systems, the magnetic torques and forces act in such a direction as to tend to ___________
A.	decrease the field energy at constant currents
B.	decrease the field co-energy at constant currents
C.	increase the field energy at constant currents
D.	none of the mentioned
Answer» D. none of the mentioned

Discussion