Electronics Paper 2, May/June 2014  
Questions: 1 2 3 4 5 6 7 Main
General Comments

Question 1
  1. Distinguish between an analogue meter and a digital meter.
  2. State the function of the following controls used in the cathode ray oscilloscope (CRO):

(i)  focus;
(ii) Y-shift;
(iii) X-shift;
(iv) intensity.


   The expected answers were:
            (a)        (i)         Analogue meter  -  Has a pointer moving across a calibrated scale. It is
used to measure voltage, current and resistance.
                          (ii)      Digital meter  -  It performs the same functions as analogue meters but
                                        displays the indicated value using a segment LED to give a numerical  
                                        value to the measurement.
            (b)        (i)         FOCUS CONTROL  -  It adjusts the spot or trace for a sharp image.
                        (ii)        Y-SHIFT  -  It moves the spot or trace up or down.
                        (iii)       X-SHIFT  -  It moves the spot or trace to the left or right.

  1. INTENSITY  -  Adjusts/controls the brightness of the CRO

                          (high or low) of  the trace/spot.
The question was on Measuring Instruments. Many candidates were able to cite mode of display of readings as one of the essential differences between analogue and digital meters. Some candidates also described well the functions of the control knobs on the oscilloscope. The performance was good because many candidates appeared to be familiar with this topic.

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