Tuesday, September 1, 2020

Chapter 3 : Electromagnetism- Page 13

Chapter 3 : Electromagnetism

121. A rectangular magnet of magnetic moment M is cut into two piece of same length , the magnetic moment of each piece will be

A. M
B. M/2
C. 2M
D. M/4

... Answer is ( B)



122. Magnetic moment is a

A. pole strength
B. universal constant
C. scalar quantity
D. vector quantity

... Answer is (D)


123. The magneto-motive force is the two

A. the voltage across the two ends of exciting coil
B. the flow of an electric current
C. the sum of all currents embraced by one line of magnetic field
D. the passage of magnetic field through an exciting coil

... Answer is (C)



124. 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

  ... Answer is (D)


125. What will be the current passing through the ring shaped air cored coil ns is 800 and ampere when number of tur turns are 3200?
Answer is (B)


126. A certain amount of current flows through a ring-shaped coil with fixed number of turns. flow does the magnetic inside the coil if an induction 13 varies iron core is threaded into coil without dimensional change of coil?
Remains same
B. First increases and then decreases depending on the depth of iron insertion

D. Increases

  ... Answer is (D)



127. The initial permeability of an iron rod is

A. the highest permeability of iron  rod
B. the lowest permeability of iron rod
C. the permeability at the end of iron rod
D. the permeability almost in non-magnetised state

... Answer is (D)


128. Which part of the magnetic path requires largest mmf.?

A. Air gap
B. Coil
C. Inductance

... Answer is (A)


129. How does the magnetic compass needle behave in a magnetic field?

A. It starts rotating
B. It assures a position which follows a line of magnetic flux
C. It assures a position right angle to magnetic field
D. None of the above
  ... Answer is (B)


130.  Which of the following type of are not very important for engineering applications?

B. Diamagnetic

D. None of the above

  ... Answer is (B)



Page 13 of  17

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