# 1000+ ECE Viva Questions and Answers Pdf - 1

Question: 1

Measurement of power factor of a 3-phase system by two wattmeter method can be obtained in case of

(A) balanced source with 3 phase, 4 wire balanced load

(B) balanced source with 3 phase, 3 wire unbalanced load

(C) balanced source with 3 phase, 3 wire unbalanced load

(D) balanced load and balanced source

Ans: D

Question: 2

A two terminal black box contains one of the R-L elements. When the black box is connected to a 220 V ac supply, the current through the source is 1. When a capacitance of 0.1 F is inserted in series between the source and the box, the current through the source is 21. The element is

(A) a resistance

(B) it is not possible to determine the element

(C) a capacitance

(D) an inductance

Ans: D

an inductance

Question: 3

In a balanced three phase star connected system, the phase voltages

(A) lags the respective line voltage by 30°

(B) leads the respective line voltages by 30°

(C) are in phase with the respective line voltage

(D) leads the respective line voltage by 90°

Ans: A

lags the respective line voltage by 30°

Question: 4

Application of Theveninâ€™s theorem in a circuit results in

(A) a voltage source and an impedance in series

(B) a current source and an impedance parallel

(C) an ideal current source

(D) an ideal voltage source

Ans: A

a voltage source and an impedance in series

Question: 5

Which of the following quantities consists of SI units as WATT?

(A) power

(B) force

(C) current

(D) charge

Ans: D

charge

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