Applied Electricity Paper 2 , Nov/Dec. 2010  
Questions:   1 2 3 4 5 6   Main
General Comments

Question 4

(a) State one application of each of the following instruments:
(i) ohmmeter;
[ii} watt-hour meter.
(b) State the function of a choke in a fluorescent fitting.
(c) The coil of a loudspeaker has 20 turns and a diameter of 15 mm. If the coil is placed in a magnetic field of flux density 0.8 T, calculate the force produced when a current of 0.1 A flows through the coil.


The expected answers were:
(a)(i) Ohmmeter is used for measuring resistance / continuity test
(ii) Watthour meter is used for measuring energy consumed
(b) The function of a choke in a fluorescent fitting is to limit the current flowing in an a.c. circuit.
(c) Active length of the coil, L = 20 X Π x 15
                                                                         1000 = 0.94m
F = BLI (Newtons)
= 0.8 x 0.943 x 0.1
= 0.07SN
The question was on Measuring Instruments and Electromagnetic Induction. It was quite unpopular. The performance was poor.
The recall question, part (a), was got by most of the candidates, while the part (b) was not attempted by many. Most of the candidates did not attempt part{c) and this was attributed to lack of exposure and experience as pointed out by the Chief Examiner.

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