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.Management Sciences
Category: Magnetism and Electromagnetism
The left hand rule correlates to______________?
A. current, induced e.m.f. and direction of force on a conductor
B. magnetic field, electric field and direction of force on a conductor
C. self induction, mutual induction and direction of force on a conductor
D. current, magnetic field and direction of force on a conductor
Air gap has_________eluctance as compared to iron or steel path?
A. little
B. lower
C. higher
D. zero
The force between two long parallel conductors is inversely proportional to_____________?
A. radius of conductors
B. current in one conductor
C. product of current in two conductors
D. distance between the conductors
Which of the following is a vector quantity ?
A. Relative permeability
B. Magnetic field intensity
C. Flux density
D. Magnetic potential
The commonly used material for shielding or screening magnetism is____________?
A. copper
B. aluminium
C. soft iron
D. brass
Temporary magnets are used in______________?
A. loud-speakers
B. generators
C. motors
D. all of the above
The unit of flux is the same as that of_______________?
A. reluctance
B. resistance
C. permeance
D. pole strength
A square cross-sectional magnet has a pole strength of 1 x 10 Wb and cross sectional area of 20 mm x 20 mm. What is the strength at a distance of 100 mm from the unit pole in air ?
A. 63.38 N/Wb
B. 633.8 N/Wb
C. 6338 N/Wb
D. 63380 N/Wb
A certain amount of current flows through a ring-shaped coil with fixed number of turns. How does the magnetic induction B varies inside the coil if an iron core is threaded into coil without dimensional change of coil ?
A. Decreases
B. Increases
C. Remains same
D. First increases and then decreases depending on the depth of iron in¬sertion
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