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.Management Sciences
Category: Magnetism and Electromagnetism
Temporary magnets are used in______________?
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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
When two ends of a circular uniform wire are joined to the terminals of a battery, the field at the center of the circle?
A. will be zero
B. will be infinite
C. will depend on the amount of e.m.f. applied
D. will depend on the radius of the circle
Gilbert is a unit of_______________?
A. electromotive force
B. magnetomotive force
C. conductance
D. permittivity
A keeper is used to_____________?
A. change the direction of magnetic lines
B. amplify flux
C. restore lost flux
D. provide a closed path for flux
Magnetism of a magnet can be destroyed by_____________?
A. heating
B. hammering
C. by inductive action of another magnet
D. by all above methods
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