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 ?

Related Mcqs:

1. What will be the current passing through the ring shaped air cored coil when number of turns is 800 and ampere turns are 3200 ?

   A. 2
   B. 4
   C. 6
   D. 8

2. A 200 turn coil having an axial length of 30 mm and a radius of 10 mm is pivoted in a magnetic field having a flux density of 0.8 T. If the coil carries a current of 0.5 A, the torque acting on the coil will be_____________?

   A. 8 N-m
   B. 0.48 N-m
   C. 0.048 N-m
   D. 0.0048 N-m

3. The electromagnet has 50 turns and a current of 1A flows through the coil. If the length of the magnet circuit is 200 mm, what is the magnetic field strength ?

   A. 2500 AT/m
   B. 250 AT/m
   C. 25 AT/m
   D. 2.5 AT/m

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

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

5. What will be the magnetic potential difference across the air gap of 2 cm length in magnetic field of 200 AT/m ?

   A. 2 AT
   B. 4 AT
   C. 6 AT
   D. 10 AT

6. 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. 2 M
   D. M/4

7. If a copper disc is rotated rapidly below a freely suspended magnetic needle, the magnetic needle shall start rotating with a velocity?

   A. less than that of disc but in opposite direction
   B. equal to that of disc and in the same direction
   C. equal to that of disc and in the opposite direction
   D. less than that of disc and in the same direction

8. When an iron piece is placed in a magnetic field_____________?

   A. the magnetic lines of force will bend away from their usual paths in order to go away from the piece
   B. the magnetic lines of force will bend away from their usual paths in order to pass through the piece
   C. the magnetic field will not be affected
   D. the iron piece will break

9. When a magnet is in motion relative to a coil the induced e.m.f. does not depend upon____________?

   A. resistance of the coil
   B. motion of the magnet
   C. number of turns of the coil
   D. pole strength of the magnet

10. The change of cross-sectional area of conductor in magnetic field will affect______________?

    A. reluctance of conductor
    B. resistance of conductor
    C. A. and B. both in the same way
    D. none of the above