148.  According to which of the alternating current values in the cross-sectional area of conductor with regard to the heating effect is selected?
A. peak value
B. half peak value
C. average value
D. r.m.s. value

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149.  The frequency of an alternating current is
A. the speed with which the alternator runs
B. the number of cycles generated in one minute
C. the number of waves passing through a point in one second
D. the number of electrons passing through a point in one second

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150.  In an A.C. circuit, the voltage and current are represented by V = Vmax sin 0, and 1= IMAX sin (0 + a) The power factor of is
A. cos a leading
B.cos a lagging
C.cos (0 + a)
D. none of the above

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151.  A pure capacitor connected across an A.C. voltage consumed 50 W. This is due to
A. the capacitive reactance in ohms
B. the current flowing in capacitor
C. the size of the capacitor being quite big
D. the statement is incorrect

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152. The power factor of a D.C. circuit is always
A. less than unity
B. unity
C. greater than unity
D. zero

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153. The product of apparent power and cosine of the phase angle between circuit voltage and current is
A. true power
B. reactive power
C. volt-amperes
D. instantaneous power

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154. The equation of 50 Hz current sine wave having r.m.s. value of 60 A is
A. 60 sin 25 t
B. 60 sin 50 t
C. 84.84 sin 314 t
D. 42.42 sin 314 t

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