169. While drawing vector diagram for a series circuit, the reference vector is

A. voltage

B. current

C. power

D. phase angle

170. For a purely resistive circuit the following statement is in correct

A. Work done is zero

B. Power consumed is zero

C. Heat produced is zero

D. Power factor is unity

171. What inductance will give the same reactance as a capacitor of 2 p F when both are at 50Hz?

A. 5 H

B. 10 H

C. 15 H

D. 20 H

172. In an A.C. circuit I sin is called

A. active component

B. wattless component

C. any of the above

D. none of the above

173. In a R-L-C circuit the impedance is given by

A. Z = R+ XL ?Xc

B. Z = R - XL + Xc

C.Z= ii(R+ XL)2 + Xc2

D.Z = 11112 + (XL - Xc)2

174. Analternating voltage V = 160 + j 120 V is applied to a circuit and the subsequent current flowing I = -6 + j 15 A. The impedance of the circuit is

A. 12 -j 3.2

B. 3.2 - j 12

C. 6.4 - j 24

D. none of the above

175. The impedance 3.2 - j12 in polar form is given as

A. 6.4 L - 75?

B. 8.4 L - 75?

C. 10.4 L-75?

D. 12.4 L - 75?

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