Applied Electricity Paper 2 , Nov/Dec. 2012  
Questions:   1 2 3 4 5 6   Main
General Comments

Question 4

(a) State the function of each of the following in a moving-coil instrument:
      (i)        deflecting device;
      (ii)        controlling device;
      (Hi)      damping device;
      (tv)      measuring scale.




The expected answers were:
(i) Deflecting device: causes the pointer of the moving coil instrument to
move from its zero position.
(H) Controlling device: causes the moving system to rest at the required
(iii) Damping device: causes the moving system to come to rest at the
deflected position without any oscillation.
(iv) Measuring scale: Is a calibrated surface which indicates the value of the
quantity to be measured.
The question was on Measuring Instruments. It was very unpopular with the
candidates. It showed that many candidates were not familiar with the basic
operating devices of a moving-coil instrument.




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