The expected answers were:
                        (a)

CONVERT FROM	TO	MULTIPLER/   FACTOR
Peak	r.m.s.	0.707
Peak	Average	0.637
Peak	Peak-to-peak	2.000

       

 

 

 

(b)        In general, instantaneous values for sinusoidal voltage signals were given by the expression.

                                                V(t) = V peak sin  (2πft)

In this case, frequency (f)  = 1000 and peak voltage Vpeak was given as 100v.

Therefore the desired expression was
                        v(t)  =  100 sin  (2000πt) volts

(c)        The instantaneous value at t = 0.2 milli-seconds was
                                    v(0.2)  =  100sin (2000π x 0.2 x 10-3)
                                   =   100sin (0.4π)
                                   =   100 x 0.951
                                   =   95.1v

This question was on circuit analysis (i.e. sinusoidal alternating current signals) characterized by the following features:
                        Vrms  =  Vmax     =   0.707Vmax
                                       √2
                        Vaverage   =  2Vmax   =   0.637Vmax
                                                 π
Most of the candidates appeared not to be aware of these relationships.

In parts b and c, many candidates missed them by taking sin (0.4 π) as sin(1.25663°) instead of sin (1.25663radians).