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.Management Sciences
Category: Electromagnetic Induction
When the motor is at its maximum speed then back emf will be______________?
A. Maximum
B. Zero
C. Intermediate values
D. No back emf
Which of the following works on torque on the current carrying conductor placed in magnetic field ?
A. galvanometer
B. ammeter
C. voltmeter
D. all of the above
cmf generated by A.C dynamo depends upon_____________?
A. number of turns in the coil
B. magnetic field strength
C. frequency of rotation
D. all of above
The alternating current has frequency of 106 Hz in such a way that time period for completion of cycle is_______________?
A. 1Hzs
B. 1.5Hzs
C. 106sec
D. 1sec
Which of the fpllowing inductor will have the least eddy current losses ?
A. Air core
B. Laminated iron core
C. Iron core
D. Powdered iron core
A laminated iron core has reduced eddy-current losses because____________?
A. more wire can be used with less D.C. resistance in coil
B. the laminations are insulated from each other
C. the magnetic flux is concentrated in the air gap of the core
D. the laminations are stacked vertfcally
A crack in the magnetic path of an inductor will result in________________?
A. unchanged inductance
B. increased inductance
C. zero inductance
D. reduced inductance
For a purely inductive circuit which of the following is true ?
A. Apparent power is zero
B. Relative power is.zero
C. Actual power of the circuit is zero
D. Any capacitance even if present in the circuit will not be charged
Non inductive resistances are used in decreasing______________?
A. Mutual inductance
B. Self inductance
C. Magnetic fields
D. Heating effect
If the coil is wound on an iron core the flux through it will_______________?
A. decrease
B. become zero
C. remain the same
D. increase
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