Electricity and Magnetic Fundamentals

11. A law establishing the fact that the algebraic su of the rises and drops of the mmf around a closed loop of a magnetic circuit is equal to zero.

  1. Kirchhoff's circuital law
  2. Maxwell's circuital law
  3. Ampere's circuital law
  4. Coulomb's circuital law

Correct answer: (C)
Ampere's circuital law

12. A law relating between the magnetic and electric susceptibilities and the absolute temperatures which is followed b ferromagnets, antiferromagnets, non-polar ferroelectrics, antiferroelectrics and some paramagnets.

  1. Curie's Law
  2. Child's Law
  3. CR Law
  4. Curie-Weiss Law

Correct answer: (D)
Curie-Weiss Law

13. A law stating that the magnetic susceptibilities of most paramagnetic substances are inversely proportional to their absolute temperatures.

  1. Curie's Law
  2. Child's Law
  3. CR Law
  4. Curie-Weiss Law

Correct answer: (A)
Curie's Law

14. A law that states that the current in a thermionic diode varies directly with the three- halves power of anode voltage and inversely with the square of the distance between the electrodes, provided operating conditions are such that the current is limited only by the space charge.

  1. Hall's law
  2. Joule's law
  3. Child's law
  4. Coulomb's law

Correct answer: (C)
Child's law

15. A law that states that the polarity of the induced voltage will oppose the change in magnetic flux causing the induction.

  1. Joule's law
  2. Faraday's law
  3. Coulomb's law
  4. Lenz' law

Correct answer: (D)
Lenz' law

16. A length of wire has a resistance of 10 ohms. What is the resistance of a wire of the same material three times as long and twice the cross-sectional area?

  1. 30 ohms
  2. 20 ohms
  3. 15 ohms
  4. 7 ohms

Correct answer: (C)
15 ohms

17. A magnetic circuit carries a flux cpi in the iron part and a flux cpg in the air gap. What is the leakage coefficient?

  1. φi/ φg
  2. φi X φg
  3. φgi
  4. φi + φg

Correct answer: (A)
φi/ φg

18. A magnetic field is

  1. The current flow through space around a permanent magnet
  2. The force set up when current flows through a conductor
  3. The force that drives current through a resistor
  4. The force between the plates of a charged capacitor

Correct answer: (B)
The force set up when current flows through a conductor

19. A magnetic flux of 2.5 x10∧4 Wb through an area of 5 x10∧4 square meters results in

  1. 5 Wb
  2. O.5 Tesia of flux density
  3. 5x 10∧-5 Wb of flux
  4. 5000 Tesia of flux density

Correct answer: (B)
O.5 Tesia of flux density

20. A magnetic material losses its ferromagnetic properties at a point called

  1. Curie temperature
  2. Inferred absolute temperature
  3. Room temperature
  4. Absolute temperature

Correct answer: (A)
Curie temperature

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