901. Overload relays are of_______________type
A. induction
B. solid state
C. thermal
D. electromagnetic
E. all above
902. Thermal overload relays are used to protect the motor against over current due to____________?
A. short-circuits
B. heavy loads
C. grounds
D. all of the above
903. Which of the following materials are diamagnetic ?
A. Silver
B. Copper
C. Silver and copper
D. Iron
904. Which of the following type of materials are not very important for engineering applications ?
A. Ferromagnetic
B. Paramagnetic
C. Diamagnetic
D. None of the above
905. 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
906. In a simple magnetic field the strength of magnet flux_______________?
A. is constant and has same value in energy part of the magnetic field
B. increases continuously from initial value to final value
C. decreases continuously from initial value to final value
D. first increases and then decreases till it becomes zero
907. The magnetic reluctance of a material______________?
A. decreases with increasing cross sectional area of material
B. increases with increasing cross-sec-tional area of material
C. does not vary with increasing cross-sectional area of material
D. any of the above
908. Which of the following statements is correct ?
A. The magnetic flux inside an exciting coil is lower than its outside surface
B. The magnetic flux inside an exciting coil is zero
C. The magnetic flux inside the exciting coil is greater than its outside surface
D. The magnetic flux inside the exciting coil is same as on its outside surface
909. The initial permeability of an iron rod is________________?
A. the highest permeability of the iron rod
B. the lowest permeability of the iron rod
C. the permeability at the end of the iron rod
D. the permeability almost in non-magnetised state
910. 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
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