6. The root mean square value of voltage (V) in an AC circuit is :
(a) 0.637Vmax
(b) 0.707 Vmax
(c) 2Vmax
(d) 2 Vmax
7. The power factor in AC circuit is equal to :
(a) Z/R
(b) R/Z
(c) RZ
(d) none of the
8. A series AC circuit has a resistance of 12 Ω and reactance 5 Ω. The impedance of circuit is :
(a) 5 Ω
(b) 12 Ω
(c) 13 Ω
(d) 17 Omega;
9. In an AC series circuit, instantaneous voltage is maximum while instantaneous current is zero. The source is connected to :
(a) pure inductor only
(b) pure resistance only
(c) pure capacitor only
(d) (a) or (c)
10. If the mean value of an alternating voltage is (28 √2)/π volt, its rms value is :
(a) 28 volt
(b) 14 volt
(c) 142 volt
(d) zero
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