A laminated iron core has reduced eddy-current losses because____________? A. more wire can be used with less D.C. resistance in coilB. the laminations are insulated from each other C. the magnetic flux is concentrated in the air gap of the…
The magnitude of the induced e.m.f. in a conductor depends on the______________? A. flux density of the magnetic field B. amount of flux cut C. amount of flux linkagesD. rate of change of flux-linkages
Which of the following is not a unit of inductance ? A. HenryB. Coulomb/volt ampere C. Volt second per ampere D. All of the above
Mutually inductance between two magnetically-coupled coils depends on____________? A. permeability of the core B. the number of their turns C. cross-sectional area of their common coreD. all of the above
The law that the induced e.m.f. and current always oppose the cause producing them is due to____________? A. FaradayB. Lenz C. Newton D. Coulomb
If current in a conductor increases then according to Lenz’s law self-induced voltage will____________? A. aid the increasing current B. tend to decrease the amount of cur-rentC. produce current opposite to the in-creasing current D. aid the applied voltage
Air-core coils are practically free from______________? A. hysteresis losses B. eddy current lossesC. both (A) and (B) D. none of the above
The property of coil by which a counter e.m.f. is induced in it when the current through the coil changes is known as__________? A. self-inductance B. mutual inductance C. series aiding inductance D. capacitance
The direction of induced e.m.f. can be found by_____________? A. Laplace’s lawB. Lenz’s law C. Fleming’s right hand rule D. Kirchhoff s voltage law
An open coil has_____________? A. zero resistance and inductanceB. infinite resistance and zero inductance C. infinite resistance and normal inductance D. zero resistance and high inductance