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Back emf refers to the

A. Current equal to the applied emf

B. Opposing emf

C. Current opposing the applied emf

D. Voltage opposing the applied emf

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  1. Theory of ferromagnetic phenomena which assumes each atom is a permanent magnet which can turn freely…
  2. Small voltages generated by a conductor with current in an external magnetic field.
  3. Hydrogen is an example of a _____ material.
  4. An effect which is generally used in the gausameter to measure flux density.
  5. Who discovered superconductivity in 1911?
  6. The customary energy unit in atomic and nuclear physics is
  7. What revolves about the positive nucleus in a definite orbit?
  8. The phenomenon by which a magnetic substance becomes a magnet when it is place near a magnet
  9. When the ferromagnetic substance is inserted in a current- carrying solenoida the magnetic field is
  10. The ratio of the total flux (flux in iron path) to the useful flux (flux in air gap)
  11. The property of magnetic materials of retaining magnetism after withdrawal of the magnetizing force…
  12. The electric potential across part AB of a circuit is 5 V; point A being at higher potential. If a charge…
  13. Permanent magnets can be found in
  14. One ampere- turn is equivalent to _____ gilberts
  15. Electric potential is a _______ quantity.
  16. One of the solid structures in which the position of the atoms or ions are predetermined
  17. If the number of valence electrons of an atom is less than 4a the substance is called
  18. The resistance of a material is ____________ its area of cross-section.
  19. In electro-mechanical conversion devices like generators and motors the reason why a small air gap is…
  20. When a wire loop is rotated in a magnetic field the direction of the induced emf changes one in every…
  21. There are how many compounds available in nature?
  22. The phenomenon that when an electric current passes through an anisotropic crystala there is an absorption…
  23. Whenever a conductor cuts magnetic fluxa an emf is induced in it. This is known as
  24. Electric field intensity is a ________.
  25. As the magnetic intensity decreasesa the relative permeability of a magnetic material
  26. Who discovereda the relationship between magnetism and electricity that serves as the foundation for…
  27. The core of a transformer heats up when its primary is fed from an ac source because of
  28. An alloy of 22 percent iron and 78 per cent nickel.
  29. The force between two magnetic poles varies with the distance between them. The variation is ______…
  30. The emf induced in a coil due to the changing current of another neighboring coil is called